Refine
Year of publication
- 2011 (52) (remove)
Document Type
- Doctoral Thesis (32)
- Article (20)
Language
- English (52) (remove)
Has Fulltext
- yes (52)
Is part of the Bibliography
- no (52)
Keywords
- - (19)
- Biosphärenreservat (2)
- Klimaänderung (2)
- Pancreatic cancer (2)
- Phosphine (2)
- Proteolyse (2)
- Staphylococcus aureus (2)
- 31P-NMR (1)
- 6606PDA (1)
- Ab-initio-Rechnung (1)
Institute
- Institut für Biochemie (5)
- Institut für Hygiene und Umweltmedizin (5)
- Institut für Physik (5)
- Abteilung für Mikrobiologie und Molekularbiologie (3)
- Institut für Community Medicine (3)
- Institut für Geographie und Geologie (3)
- Institut für Mathematik und Informatik (3)
- Institut für Botanik und Landschaftsökologie & Botanischer Garten (2)
- Institut für Immunologie u. Transfusionsmedizin - Abteilung Immunologie (2)
- Institut für Pharmazie (2)
Publisher
- S. Karger AG (19)
- IOP Publishing (1)
Chromosomal abnormalities, like deletions, amplifications, inversions or translocations, are recurrent features in haematological malignancies. However, the precise molecular breakpoints are frequently not determined. Here we describe a rapid analysis of genetic imbalances combining fine tiling comparative genomic hybridization (FT-CGH) and ligation-mediated PCR (LM-PCR). We clarified an inv(14)(q11q32) in a case of T cell acute lymphoblastic leukaemia with a breakpoint in the TRA/D in 68% of cells detected by fluorescence in situ hybridization. FT-CGH showed several mono- and biallelic losses within TRA/D. LM-PCR disclosed a TRA/D rearrangement on one allele. The other allele revealed an inv(14)(q11q32), joining TRDD2 at 21,977,000 of 14q11 together with the IGH locus at 105,948,000 and 3′-sequence of TRAC at 22,092,000 joined together with IGHV4–61 at 106,166,000. This sensitive approach can unravel complex chromosomal abnormalities in patient samples with a limited amount of aberrant cells and may lead to better diagnostic and therapeutic options.
Three-dimensional (3D) dynamical properties of fast particles being injected into the void region of a dusty plasma under microgravity conditions have been measured. For that purpose, a stereoscopic camera setup of three cameras has been developed that is able to track and reconstruct the 3D trajectories of individual dust particles. From more than 500 particle trajectories, the force field inside the void region and its influence on particle movement are derived and analyzed in 3D. It is shown that the force field is dominated by forces pointing radially out of the void and that this radial character is reflected in the velocity distributions of particles leaving the void. Furthermore, the structure of the force field is used for measuring the neutral gas friction for the particles inside the void.
Background: Cardiovascular diseases are the leading cause of death worldwide. Subclinical alterations of the cardiovascular system, such as increased exercise blood pressure or an endothelial dysfunction confer a higher risk of manifest cardiovascular diseases and incident events. Detecting associations between circulating markers of the endocrine-metabolic system and the subclinical cardiovascular phenotypes could be useful to better understand cardiovascular disease progression and to improve risk prediction for manifest cardiovascular diseases. Methods: The associations between (a) serum thyroid-stimulating hormone and increased exercise blood pressure, (b) serum hemoglobin A1c and endothelial dysfunction as well as (c) serum insulin-like growth factor I and endothelial dysfunction were studied using cross-sectional data from around 1400 subjects aged 25 to 85 years collected during the 5-year follow-up of the population-based Study of Health in Pomerania (SHIP-1). Increased exercise blood pressure was defined as a value above the sex- and age-specific 80th percentile measured at the 100 W stage of a symptom-limited bicycle ergometry test. Endothelial dysfunction was defined as an impaired flow-mediated dilation measured as a continuous decrease or below the median of sex-specific distribution. Non-fasting blood samples were drawn from the cubital vein in the supine position. Results: The odds for increased systolic exercise blood pressure (odds ratio 1.24, 95% confidence interval 0.88; 1.76) and diastolic exercise blood pressure (odds ratio 0.98, 95% confidence interval 0.70; 1.39) as well as for exercise-induced increase of systolic and diastolic blood pressure were not significantly different between subjects with high and low serum thyroid-stimulating hormone levels within the reference range. In women without current use of antihypertensive medication, increasing serum hemoglobin A1c levels were associated with decreasing flow-mediated dilation levels (ß = -1.17, 95% confidence interval -2.03; -0.30). Such an association was not found in men. In men, logistic regression analysis revealed an odds ratio of 1.27 (95% confidence interval 1.07; 1.51) for decreased flow-mediated dilation for each decrement of serum insulin-like growth factor I standard deviation. In women, no significant association between serum insulin-like growth factor I levels and flow-mediated dilation was observed (odds ratio 0.88, 95% confidence interval 0.74; 1.05). Conclusions: Based on the presented results it is concluded that (a) serum thyroid-stimulating hormone levels are not associated with exercise blood pressure in the general population, (b) higher serum hemoglobin A1c levels in non-diabetic subjects are inversely associated with flow-mediated dilation in women without antihypertensive medication, but not in men, and (c) lower serum insulin-like growth factor I levels are associated with impaired endothelial function in men, but not in women. Therefore the metabolic marker hemoglobin A1c and the endocrine marker insulin-like growth factor I might be markers facilitating the identification of subjects at high risk of subclinical cardiovascular alterations.
Novel heterocyclic alpha-phosphinoamino acids, by structural relationship named 3-phosphaprolines, were obtained by cyclocondensation of 2-phenylphosphinoethylamines with glyoxylic, pyruvic or phenylglyoxylic acid at room temperature in diethylether. The reactions proceed via primary attack of the P-lone electron pair, as shown by the synthesis of phosphonium glycolates from tertiary phosphines and glyoxylic acid, and addition of PH at the carbonyl group. The ring closure proceeds by replacement of the hydroxy by the amino group and is kinetically controlled. NMR monitoring of the phosphaprolines in CD3OD over several days indicates changes of the diastereoisomer ratios leading to higher contents of the more stable trans-diastereoisomers. The zwitterionic compounds are soluble in part in CD3OD, DMF or DMSO, are somewhat sensitive to air in solution and may undergo hydrolysis with larger amounts of water. The structures are proved by multinuclear NMR spectra and two crystal structure analyses. Suitable phosphaprolines as well phosphonium glycolates and Ni(COD)2 allow to generate precatalysts, activated by NaH for the oligomerisation of ethylene to mainly linear products with methyl and vinyl end groups. Some additional investigations with phosphinophenolates, another type of P-C-C-O- ligands, were performed for comparison. Precatalysts prepared from 2-phosphinophenolesters and Ni(COD)2 at room temperature were characterized by multinuclear NMR but decomposed on heating to stable nickel cis-bis(P,O-chelate) complexes. Heating precatalysts generated from a phosphinophenolester or phosphinophenols and Ni(COD)2 in the presence of ethylene under pressure led to linear ethylene oligomers. These reactions are much faster than the above mentioned conversions with NaH activated P,O-Ni-catalysts. In the presence of 9-decenol with unprotected remote hydroxyl group incorporation of a small amount of isolated hydroxyoctyl side groups takes place, detected by 13C NMR spectroscopy. Finally it is stated that the development of a facile synthesis and the characterization of the properties of the phosphaprolines pave the way for derivatisation and further studies with these novel types of amino acids.
Phosphines are highly versatile ligands for transition metal catalysts because of wide tuning abilites of their stereoelectronic properties. Bulky and basic phosphines, to a smaller extend also π-acidic phosphites were intensively studied whereas dicoordinated trivalent phosphorus compounds were comparatively little investigated in this respect. In part this may go back to the limited stability of many P=C compounds, in the case of the stable benzazaphosphole to low stabilityof complexes with non-zero-valent transition metals. With the availability of suitable chelate complexes this problems may be overcome. Because biaryl phosphines proved particularly useful as chelate ligands this work is focused on the development of convenient syntheses of new biaryl-type N-heterocyclic or functionally aryl substituted 1,3-benzazaphosphole P,N- P,P- and P,O-chelate ligands and the characterization of their structures. The pivotal point was to find an applicable synthetic route to the title ligands. Because currently transition metal catalyzed cross-coupling reactions are a hot field in catalytic research, the initial target of my work was the investigation of the applicability of suitable biaryl coupling reactions on 1,3-benzazaphospholes. There are several types of transition metal catalyzed biaryl couplings. One reaction, which is currently in the main focus by use of non-toxic and air stable coupling partners, often allowing water as environmental friendly solvent, is the Pd-catalyzed Suzuki-Miyaura coupling of an aryl halide with an arylboronic acid. To apply the Suzuki coupling to the synthesis of biaryl-type benzazaphospholes, the synthesis of either benzazaphosphol-2-boronic acids or reactive 2-halogen-benzazaphospholes have to be performed. Because of the successful introduction of functional groups in position 2 of benzazaphospholes via lithiation and reaction with electrophiles, the 2-lithiation of suitably available N-substituted benzazaphospholes and introduction of boryl groups or halogen by reaction with boronic acid esters or with a halogenating reagent like dibromoethane appeared as a realistic route and was chosen for closer study. N-Neopentyl-benzazaphosphole was selected by its relatively easy access and N-mesityl-benzazaphosphole as a N-aryl representative. From the two principal methods developed to synthesize 1,3-benzazaphospholes, only the synthesis and reduction of o-aniline phosphonic acid esters to o-phosphinoanilines and subsequent [4+1] cyclocondensation is promising to access N-substituted 2-CH benzazaphospholes. My first investigations targeted to improve the synthesis of the benzazaphosphole precursors. The invention of a Cu- instead of the earlier used Pd-catalyzed P-C coupling allows a more economical access to anilinophosphonates which were then transformed to 2H-1,3-benzazaphospholes by the established orthoformamide cyclocondensation. Several attempts of the coupling with careful control of dryness of all reagents and solvents were made in order to obtain pure 1,3-benzazaphosphole-2-boronic acid ester and, after mild hydrolysis, to isolate 1,3-benzazaphosphole-2-boronic acid. The coupling worked with N-mesityl-1,3-benzazaphosphole 13e, but the benzazaphosphol-2-boronic acid could not be obtained in pure form because of easy B-C bond cleavage during crystallization, certainly by the two ‘OH groups. For attempts with a reverted methodology, the synthesis of a 2-bromo-substituted benzazaphosphole was studied, which should be coupled with (hetero)arylboronic acids via Suzuki-Mijaura reaction. However, the 2-bromo-benzazaphosphole also could not be obtained in pure form, and a coupling experiment with phenyl boronic acid and catalysis with ligand free Pd/C failed. Therefore, other routes to biaryl-type benzazaphospholes were envisaged. Direct C-H functionalization has emerged over the past few years as an attractive strategy to enhance molecular complexity. This holds also for π-excess-type heterocycles like indoles, benzoxazoles or purines which allow direct CH-arylation in 2-position. These reactions generally involve palladium based catalysts and in some cases rhodium catalysts. In a series of experiments the catalytic arylation, heteroarylation and later also alkylation were studied with 1,3-benzazaphospholes 13a-e as precursors. The initial studies were carried out with iodobenzene, keeping similar reaction conditions as for 2-CH arylation of indoles. Then transition metal catalysts, bases and conditions were varied. The necessity and influence of a catalyst was established by blind experiments without transition metal catalyst which led to strong decrease of the reactivity. However, the transitional metal catalyzed reactions of N-substituted-1,3-benzazaphosphole with aryl- and heteroaryl halides did not give the desired 2-aryl-substituted 1,3-benzazaphosphole biaryl ligands but revealed a novel oxidative addition at the P=C double bond. In the presence of moisture benzazaphospholine-P-oxides are formed. Further exploration of the scope of this reaction showed that it is applicable to several functionally substituted aryl halides and heteroaryl halides. As besides PdX2 (X = Cl, OAc) also Pd(0)(PPh3)4 was found active as catalyst, it can be assumed, that the reaction occurs via a Pd(0) species and oxidative addition of the aryl halide at Pd(0). Because Pd(0) will coordinate stronger to the π-acidic benzazaphosphole than Pd(II) it is assumed that in the first step small equilibrium amounts of a Pd(0)benzazaphosphole complex will be formed which undergo the oxidative addition and then react to benzazaphospholium salt and furnish back a Pd(0) complex with 1,3-benzazaphosphole ligand. The benzazaphospholium salts are highly sensitive to moisture and react with traces of water to form benzazaphospholine-P-oxides 20 and acid, neutralized by the base. A cyclic species RR’P(OH)=CHR”, where the halogen is replaced by OH, may be assumed as intermediate which undergoes a rearrangement to the more stable RR’P(=O)-CH2R” tautomer, driven by the high P=O bond energy. After various investigations of the optimum conditions for the reaction, a number of new functionally substituted P-aryl or P-heteroaryl benzazaphospholine P-oxides and 1,3-dineopentyl-benzazaphospholine-3-oxide were isolated and characterized by 1H, 31P, 13C and HRMS data and two by crystallography. The biaryl-type 2-phenyl-1,3-benzazaphosphole is known since the earliest reports of these heterocycles, synthesized by cyclocondensation of 2-phosphinoaniline with benziminoester hydrochloride or in low yield with benzaldehyde. The latter method was further developed because of the compatibility of the aldehyde group with various donor functions. 2-Phosphinoaniline (12a) and 2-phosphino-4-methylaniline (12b) were heated with pyridine-2-carboxaldehyde under varied conditions, and a crucial role of acid catalyst was observed in the investigation. The results showed that the dehydrogenating cyclocondensation, if catalyzed by a suitable type and amount of acid catalyst, works well for primary phosphinoanilines 12a,b and a variety of reactive aldehydes, including N-heterocyclic and o- or m-functionally substituted arylaldehydes. In an equimolar ratio, on heating usually hydrogen is eliminated, at least formally, to furnish the aromatically stabilized 1H-1,3-benzazaphosphole ring systems of 35 whereas in other cases reductive side reactions occur, e.g. the N-CH2R substitution to 36 in reactions with two equivalents of aldehyde. Thus the synthesis of 1,5-dimethyl-1,3-benzazaphosphole (36a) was achieved by double cyclocondensation of 12b and formaldehyde in a 1:2 molar ratio. This provides the so far shortest way to synthesize N-substituted 1,3-benzazaphospholes and suggests, that the reaction is generally applicable in reactions with two equivalents of monoaldehyde. This puts the question if N-secondary o-phosphinoanilines such as N-neopentyl-2-phosphinoaniline (12d) can be cyclocondensed with aldehydes to benzazaphospholes or if a primary amino group is required. The successful experiment shows that cyclocondensation of N-secondary o-phosphinoanilines with suitable aldehydes is possible. N-Neopentyl-2-pyrido-1,3-benzazaphosphole was obtained in high yield. An interesting extension of the above reaction are cyclocondensations with compounds bearing two aldehyde groups. Double condensation of 12b with o-phthaldialdehyde was performed. It proceeded fast and gave tetracyclic-1,3-benzazaphosphole in high yield. Based on the NMR monitored primary formation of organoammonium phosphino glycolates from amines, phosphines and glyoxylic acid, followed by conversion to phosphinoglycines, it is assumed that the reaction proceeds by initial attack of the primary phosphino group of 12b at the carbonyl carbon atom of R-CHO, polarized with the help of the acid catalyst. The resulting P-C bonded secondary phosphine, containing an α-hydroxy group, may release water after transfer of a proton to oxygen in equilibrium, followed by attack of amine. This leads to formation of the dihydro-intermediate 34, observed by NMR reaction monitoring in several cases. Possible ways are releasing of H2 during reflux, directly giving 2-substituted NH-1,3-benzazaphospholes 35, or hydrogen transfer, connected e.g. with N-substitution leading to 1,2-disubstituted 1,3-benzazaphospholes 36. The second path is observed mainly when excess or double molar quantities of aldehydes are used at the start of the reaction. The two hydrogen atoms at P and C2 are consumed during the second condensation and formation of the NCH2R group and generate the P=C double bond. Finally, cyclocondensation of o-phosphinoanilines with aldehydes has proven as a useful method for the synthesis of biaryl type benzazaphosphole ligands. After thorough investigations, N-primary and secondary phosphino anilines were found cyclisable with various heteroaryl aldehydes upon refluxing in toluene in the presence of a suitable acid catalyst, and 11 new compounds were synthesized following this procedure and characterized by 1H, 31P, 13C NMR and HRMS data. For two compounds crystal structures were also obtained. First attempts to synthesize chelate complexes with the 2-(hetero)aryl-1,3-benzazaphospholes were started. A soluble 2-(o-diphenylphosphinophenyl)-1,3-benzazaphoasphole-Cr(CO)4 chelate complex was detected by NMR spectroscopy, whereas most products of the new ligands with Rh(COD) or NiCp complexes were insoluble in usual NMR solvents and require further efforts for synthesis and full analytical and structural characterization.
Triple helix-forming oligonucleotides (TFOs) are one of the most specific DNA duplex binding agents and offer new perspectives towards oligonucleotide-mediated gene regulation and manipulation. However, the poor thermodynamic stability of DNA triplexes under physiological conditions limits a successful application in the antigene strategy. Thus, the conjugation of TFOs with small triplex-specific binding ligands is a promising approach to stabilize the formed complexes and to enhance their overall binding affinity. The present study focused on the synthesis of novel TFO conjugates with triplex-binding indolo[3,2-b]quinoline derivatives (PIQ) and on their ability to form and stabilize intermolecular triplexes through their recognition of a duplex target. During the course of the work the thermodynamics of conjugate binding and structural aspects of drug-DNA interactions have been characterized by a variety of spectroscopic and calorimetric techniques.
The present work provides new insight concerning histidine phosphorylation in proteins, which is an essential regulatory posttranslational modification. To study histidine phosphorylation, a newly developed NMR approach, the HNP experiment, is presented in this thesis. The HNP experiment provides specific experimental evidence of phosphorylated histidines in proteins. It allows for the determination of the regiochemistry of phosphohistidines on the basis of three individual peak patterns for distinguishing all three phosphohistidines i.e. 1- and 3-phosphohistidine and 1,3-diphosphohistidine. This novel NMR approach allows the investigation of histidine phosphorylation in proteins under physiological conditions without resorting to chemical shift comparisons, reference compounds, or radioactively labelled phosphate. In this thesis, histidine phosphorylation in the regulatory domains PRDI and PRDII of the Bacillus subtilis antiterminator protein GlcT was intensely studied. GlcT is a transcription factor, which regulates the phosphotransferase system (PTS) by modulating the expression level of PTS-enzymes (Enzyme I, HPr, Enzyme II) on a transcriptional level. Upon the phosphorylation of conserved histidines in PRDI and PRDII, the function of GlcT is regulated through its aggregation state. In this thesis, it is shown that histidines in both PRDs are primarily phosphorylated at their N(Epsilon-2), forming 3-phosphohistidine. In addition, we found, by newly optimized mass spectrometry conditions, that both PRDs are dominantly onefold phosphorylated. By using tandem mass spectrometry to study PRDI, we identified histidine 170, which is the second of two conserved histidines (His 111 and His 170), as the phosphorylation site. In this thesis, it is also shown through comprehensive mutational studies that both conserved histidines (His 218 and His 279) in PRDII can be individually phosphorylated. This is in good agreement with mass spectrometry results that indicated an additional twofold phosphorylation in PRDII. This can be explained as follows: an intra-domain phosphate transfer between both conserved histidines in PRDII might be involved in the phosphorylation reaction, finally leading to a mainly onefold phosphorylated PRDII at one of the two conserved histidines. This minor twofold phosphorylation has also been found in PRDI. However, the specific peak pattern in the HNP-spectra of PRDI strongly suggest that this additional phosphorylation originates from a 1,3-diphosphohistidine, most likely at histidine 170. Furthermore, for the first time the existence of 1,3-diphosphohistidine in a protein was found. We also show that the phosphorylation of PRDI can be achieved in the absence of Enzyme II which is in contrast to the literature. Shown by analytical gel filtration, the monomeric aggregation state of PRDI obtained upon Enzyme II-free phosphorylation is identical to the monomeric aggregation state which was proposed for the Enzyme II-dependent phosphorylation of GlcT. As shown in this thesis, the combined results of HNP-NMR, mass spectrometry and analytical gel filtration deepen our understanding of regulatory histidine phosphorylation in the individual PRDI and PRDII domains of the Bacillus sub- tilis GlcT. I anticipate that this approach will be applicable to study histidine phosphorylations in other phosphoproteins.
Background: Alcohol consumption accounts for a high burden of disease. The general population of West Pomerania has been characterized as a population at risk with a high prevalence of behavioural risk factors such as alcohol risk drinking. This is reflected by the high proportion of patients being admitted to general hospitals due to alcohol-attributable diseases. The aims of the present dissertation were (a) to analyze dose-response relations between volume of alcohol drinking and the risk of diseases with different alcohol-attributable fractions (AAF) in general hospital inpatients (study 1); (b) to assess motivation to change drinking behaviour and motivation to seek help for alcohol problems during their hospital stay as well as changes in motivation to change drinking behaviour, motivation to seek help and changes in daily alcohol consumption across time according to diseases with different AAFs (study 2); and (c) to investigate the association of fatty liver disease (FLD) with blood pressure and hypertension in a general population sample and to test for the specific contribution of alcohol consumption to this association (study 3). Methods: For studies 1 and 2, data from 'Early Intervention at General Hospitals', a randomized controlled trial to test the effectiveness of brief intervention for alcohol problem drinking in general hospitals, were used. Study 1 comprised data from 846 inpatients, study 2 comprised data from 294 inpatients aged 18 to 64 years with alcohol problem drinking and alcohol-attributable diseases from four general hospitals in West Pomerania. Hospital diagnoses were classified according to their AAF: (1) diseases wholly attributable to alcohol consumption by definition (AAF=1), (2) diseases partially attributable to alcohol consumption (AAF<1), and (3) diseases with no relation to alcohol consumption or where alcohol consumption has been found to be a protective factor (AAF=0). Study 3 encompassed data from the 'Study of Health in Pomerania', a general population sample of 3191 adults aged 20-79 years. FLD was defined using ultrasound in combination with increased serum alanine aminotransferase levels. Results: Analyses showed that 46.8% of the general hospital inpatients had a disease attributable to alcohol consumption. There was a dose-response relationship between volume of alcohol drinking and the risk of diseases with different AAFs. Inpatients consuming >120 g and inpatients consuming 61-120 g of pure alcohol per day revealed significantly higher odds for diseases with AAF=1 compared to inpatients consuming 31-60 g of pure alcohol per day with odds ratios (OR) of 6.3 (95% CI 3.6-11.3) and 2.9 (95% CI 1.6-5.1), respectively. Regarding diseases with AAF<1, inpatients consuming >120 g of pure alcohol per day had significantly higher odds compared to inpatients consuming 31-60 g of pure alcohol per day (OR 2.0, CI 1.2-3.4). Analyses on motivation to change drinking behaviour and on motivation to seek help at hospitalization revealed that motivation to change drinking behaviour was higher among inpatients with alcohol-attributable diseases than among inpatients without alcohol-attributable diseases (p<.001). Among inpatients with AAF=1, motivation to seek help was higher than among inpatients with AAF<1 and AAF=0 (p<.001). While motivation to change drinking behaviour remained stable within one year after hospitalization in all three AAF groups, motivation to seek help decreased in this time period. The volume of alcohol consumed decreased in all three AAF groups within one year after hospitalization. Data from the general population study revealed that FLD was associated with blood pressure and hypertension at baseline and at five-year examination follow-up. For example, the chance of hypertension at both time points was threefold higher in individuals with FLD (OR 2.8, CI 1.3-6.2; OR 3.1, CI 1.7-5.8, respectively) compared to individuals without FLD. Analyses further revealed that the association of FLD with blood pressure and hypertension was independent of alcohol consumption. Conclusion: The results of the present dissertation provide relevant implications for public health. In view of the high proportion of general hospital inpatients with alcohol-attributable diseases, a screening procedure for problem drinking is needed. Furthermore, appropriate interventions considering the inpatient’s motivational level have to be implemented. The concept of AAFs to classify disease conditions according to their causal relationship with alcohol consumption might be a tool to detect inpatients with problem drinking. The results regarding FLD and its association with blood pressure and hypertension demonstrate that it is important to pay attention to alcohol-attributable diseases in the general population and that alcohol-attributable diseases are associated with subsequent serious sequelae. The results of the present work further indicate that the concept to distinguish between alcoholic and non-alcoholic origin of FLD might be obsolete and should be replaced by a concept that regards FLD as a multifactorial disease condition.
In this thesis, two novel assay systems had been developed, which allow a fast and easy screening for amine transaminase activity as well as the characterization of the amino donor and acceptor specificity of a given amine transaminase. The assays overcome some limitations of previously described assays but of course have some limitations themselves. The relatively low wavelength of 245 nm, at which the production of acetophenone is detected with the spectrophotometric assay, limits the amount of protein/crude extract that can be applied, which eventually results in a decreased sensitivity at higher enzyme loads due to an increased initial absorbance. Otherwise, this assay can be used very easily for the investigation of the amino acceptor specificity and both pH and temperature dependencies of amine transaminases. The conductometric assay is – by its very nature – limited to low-conducting buffers, a neutral pH and constant temperatures. In summary, the assays complement one another very well and the complete characterization of the most important enzyme properties can be accomplished quickly. Furthermore, we developed and applied a novel in silico search strategy for the identification of (R)-selective amine transaminases in sequence databases. Structural information of probably related proteins was used for rational protein design to predict key amino acid substitutions that indicate the desired activity. We subsequently searched protein databases for proteins already carrying these mutations instead of constructing the corresponding mutants in the laboratory. This methodology exploits the fact that naturally evolved proteins have undergone selection over millions of years, which has resulted in highly optimized catalysts. Using this in silico approach, we have discovered 17 (R)-selective amine transaminases. In theory, this strategy can be applied to other enzyme classes and fold types as well and for this reason constitutes a new concept for the identification of desired enzymes. Finally, we applied the seven most promising candidates of the identified proteins to asymmetric synthesis of various optical pure amines with (R)-configuration starting from the corresponding ketones. We used a lactate dehydrogenase/glucose dehydrogenase system for the necessary shift of the thermodynamic equilibrium. For all ketones at least one enzyme was found that allowed complete conversion to the corresponding chiral amine with excellent optical purities >99% ee. Bearing in mind that until last year there was only one (R)-selective amine transaminase commercially available and two microorganisms with the corresponding activity described, the identification of numerous enzymes is a breakthrough in asymmetric synthesis of chiral amines.