Improvement of a stereoselective biocatalytic synthesis by substrate and enzyme engineering: 2-hydroxy-(4'-oxocyclohexyl)acetonitrile as the model.

Even if biocatalysis is finding increasing application, it still has to gain widespread use in synthetic chemistry. Reasons for this are limitations that enzymes have with regard to substrate range, reaction scope, and insufficient selectivity with unnatural compounds. These shortcomings can be challenged by enzyme and/or substrate engineering, which are employed to alter substrate specificity and enhance the enzyme selectivity toward unnatural substrates.

Ortho-lithiation of free ferrocenyl alcohols: a new method for the synthesis of planar chiral ferrocene derivatives.

An ortho-metalation method for free ferrocenyl alcohols has been developed, which allows preparation of planar chiral ferrocene derivatives with high yields and diastereoselectivities.

De-racemization of enantiomers versus de-epimerization of diastereomers--classification of dynamic kinetic asymmetric transformations (DYKAT).

The isolation of single stereoisomers from a racemic (or diastereomeric) mixture by enzymatic or chemical resolution techniques goes in hand with the disposal of 50% (racemate) or more (diastereomeric mixtures) of the "undesired" substrate isomer(s). In order to circumvent this drawback, dynamic systems have been developed for the de-racemization of enantiomers and the de-epimerizations of diastereomers. Key strategies within this area are discussed and are classified according to their underlying kinetics, that is, dynamic kinetic resolution (DKR), dynamic kinetic asymmetric transformations (DYKAT), and hybrids between both of them.

Potential and capabilities of hydroxynitrile lyases as biocatalysts in the chemical industry.

The application of hydroxynitrile lyases (HNLs) as catalysts for the stereoselective condensation of HCN with carbonyl compounds has been reported as early as 1908. This enzymatic C-C bond coupling reaction furnishes enantiopure cyanohydrins which serve as versatile bifunctional building blocks for chemical synthesis. Screening of natural sources led to the discovery of both (R)- and (S)-selective HNLs, and several distinctly different classes of these enzymes with substantial differences concerning sequence, structure, and mechanism have been found.

Counteracting expression deficiencies by anticipating posttranslational modification of PaHNL5-L1Q-A111G by genetic engineering.

(R)-2-chloromandelic acid represents a key pharmaceutical intermediate. Its production on large scale was hampered by low turnover rates and moderate enantiomeric excess (ee) using enzyme as well as metal catalysts. The cloning and heterologous overexpression of an (R)-hydroxynitrile lyase from Prunus amygdalus opened a way to large-scale production of this compound.

Stereoselective biocatalytic synthesis of (S)-2-hydroxy-2-methylbutyric acid via substrate engineering by using "thio-disguised" precursors and oxynitrilase catalysis.

3-Tetrahydrothiophenone (4) and 4-phenylthiobutan-2-one (7) were used as masked 2-butanone equivalents to give the corresponding cyanohydrins 5 (79 % yield, 91 % ee) and 8 (95 % yield, 96 % ee) in an enzymatic cyanohydrin reaction applying the hydroxynitrile lyase (HNL) from Hevea brasiliensis. After hydrolysis and desulphurisation the desired intermediate (S)-2-hydroxy-2-methylbutyric acid (10) was obtained with 99 % ee. Interestingly, when applying (R)-selective HNL from Prunus amygdalus again the (S)-cyanohydrin 5 was formed (62 % ee).

Stereoselective hydroxylation of an achiral cyclopentanecarboxylic acid derivative using engineered P450s BM-3.

Substrate engineered, achiral carboxylic acid derivative was biohydroxylated with various mutants of cytochrome P450 BM-3 to give two out of the four possible diastereoisomers in high de and ee. The BM-3 mutants exhibit up to 9200 total turnovers for hydroxylation of the engineered substrate, which without the protecting group is not transformed by this enzyme.

Enzymatic hydrolysis of cyanohydrins with recombinant nitrile hydratase and amidase from Rhodococcus erythropolis.

Nitrile hydratase and amidase from Rhodococcus erythropolis CIMB11540 were both cloned and expressed in Escherichia coli. Crude cell free extracts were used for the hydrolysis of different aromatic cyanohydrins. Nitrile hydratase expression was increased up to 5-fold by redesign of the expression cassette.

Conversion of aliphatic 2-acetoxynitriles by nitrile-hydrolysing bacteria.

The enzymatic hydrolysis of the nitrile group of different 2-acetoxynitriles was investigated in order to obtain catalysts that chemoselectively hydrolyse nitriles in the presence of ester groups. The biotransformation of four 2-acetoxynitriles [2-acetoxybutenenitrile (ABN), 2-acetoxyheptanenitrile (AHN), 2-acetoxy-2-(2-furyl)acetonitrile (AFN), and 2-acetoxy-2,3,3-trimethylbutanenitrile (ATMB)] by different bacterial strains that synthesise nitrilases or nitrile hydratases was studied. ABN, AHN and AFN were converted by various microorganisms belonging to different bacterial genera (e.

The use of substrate engineering in biohydroxylation.

In the biohydroxylation of nonactivated carbon atoms, substrate engineering has been found to be a very useful and simple means to influence substrate acceptance and the regioselectivity and stereoselectivity of this transformation. Recently, this methodology has been applied to the hydroxylation of a large number of compounds including cycloalkane carboxylic acids, ketones, amines, amides and alcohols.

Relation between depression and anxiety in dystonic patients: implications for clinical management.

Past clinical research has identified depression as the most common psychiatric disorder associated with cervical dystonia (CD). The purpose of our study is to document different patterns of psychopathology, the frequency of psychiatric disorders, and possible correlation with the neurological disorder in patients with CD. Forty patients with CD were investigated to assess levels of psychopathology on two self-rated scales: the Beck Depression Inventory (BDI) and Symptom Check List (SCL-90).

Oxidative biotransformations using oxygenases.

Considerable progress has been made in manipulating oxidative biotransformations using oxygenases. Substrate acceptance, catalytic activity, regioselectivity and stereoselectivity have been improved significantly by substrate engineering, enzyme engineering or biocatalyst screening. Preparative biotransformations have been carried out to synthesize useful pharmaceutical intermediates or chiral synthons on the gram to several-hundred-gram scale, by use of whole cells of wild type or recombinant strains.

[The course of illness and problems of schizophrenic women and men from the relatives' perspective].

Objectives: Members of HPE, an Austrian self-help organization for the relatives of mentally ill people, were questioned about their opinion with regard to the situation of families with a mentally ill member.

Methods: A questionnaire was sent to the addresses of members of this self-help organisation. 182 respondents reported to care for 132 male and 50 female sufferers diagnosed as having a psychosis from the schizophrenic spectrum replied.

Naltrexone as a treatment of self-injurious behavior--a case report.

Objective: Self-injurious (SIB) is a phenomenon associated with different psychopathological conditions such as psychosis, mental retardation and especially severe personality disorders--mainly of the borderline subtype. It has been suggested that a blockade of the endogenous opoid system might lead to a reduction of the urge to SIB.

Method: The case and successful treatment of SIB with naltrexone in a patient with borderline personality disorder and dysthymia is described.

The concept of docking and protecting groups in biohydroxylation.

The hydroxylation of unactivated carbon atoms employing methods developed in the realms of classical organic chemistry is difficult to achieve and the processes available lack the degree of chemo-, regio- and enantioselectivity required for organic synthesis. To improve this situation, the concept of docking/protecting groups should enable the organic chemist to employ biohydroxylation as an easy tool for preparative work. Similar to the common practice of using protective groups in organic chemistry, a docking/protecting (d/p) group is introduced first, then the biotransformation is performed, and finally the d/p group is removed.

Psychological disorders in survivors of torture: exhaustion, impairment and depression.

Post-traumatic stress disorder (PTSD) has been described as the characteristic sequel to extreme events in life such as war and especially torture. This limitation to a single approach in regard to diagnosis and treatment has been criticised as being a too narrow concept to describe the effects following extreme events in life, especially as most studies so far were limited to PTSD and a small range of symptoms or disorders. The study presents data on psychiatric disorders in a group of exiled survivors of torture presenting to an out-patient department for psychiatry.

Psychiatric disorders in patients with blepharospasm - a reactive pattern?

Objective: The purpose of this study was to assess the life-time prevalence of all major psychiatric disorders in patients suffering from blepharospasm.

Method: A total of 31 consecutive patients with blepharospasm attending the Department of Neurology were interviewed at the Department of Psychiatry at the University of Vienna. Patients had been submitted to standard neurological diagnostic procedures, psychiatric diagnoses were made with the help of the SCID, functional impairment was assessed by the General Assessment of Functioning Scale (GAF).

Delusional pregnancy in a patient with primary sterility.

The case of a patient suffering from primary sterility who developed a well-systemized delusion of pregnancy is described. The patient did not have a history of psychiatric disorder or organic cerebral pathology. No history of epilepsy was detected in this patient contrary to the reports in the literature, and these facts have pathogenic relevance in delusional pregnancy.

Dysphoria from a transnosological perspective.

The objective of our psychopathological analyses is to shed light on the position of irritable mood (dysphoria) in psychiatric diagnostics and nosology. In today's most commonly applied classification systems, the ICD-10 and the DSM-IV, dysphoria is mentioned mostly in the context of diagnostic criteria of personality and affective disorders. Other authors have emphasized the importance of dysphoric states in organic psychoses and delusional disorders.

The synthesis of chiral cyanohydrins by oxynitrilases.

Enantiomerically pure cyanohydrins are important synthetic intermediates for pharmaceuticals and agrochemicals. They are produced by enzyme-catalysed synthesis using oxynitrilases. Sufficient quantities of enzyme are available via cheap natural sources and there have been recent advances in overexpression production of cyanohydrins on an industrial scale.