Current
Organic Chemistry, Volume 7, No. 13, 2003
Contents
Enzymatic Catalysis
Guest Editor: Bruno Danieli
Synthetic
Applications of Nitrile-Converting Enzymes Pp. 1279-1295
Veronika Mylerova
Properties
and Synthetic Applications of Ammonia-Lyases Pp. 1297-1315
Laszlo Poppe and Janos Retey
Laccases
and Phenol Oxidases in Organic Synthesis – a Review Pp. 1317-1331
Stephanie G. Burton
Biocatalysis
in Reaction Mixtures with Undissolved Solid Substrates and Products Pp. 1333-1346
Rein V. Ulijn, Luigi De Martin, Lucia Gardossi and Peter
J. Halling
Enzyme-Mediated
Syntheses of Chiral Communication Substances: Fragrances for Perfumery
Applications Pp. 1347-1367
Elisabetta Brenna
Microbial/Enzymatic
Synthesis of Chiral Intermediates for Pharmaceuticals:Case Studies from BMS Pp. 1369-1386
Ramesh N. Patel
Enzymatic
Synthesis of Polyphenols Pp.
1387-1397
Hiroshi Uyama and Shiro Kobayashi
Enzyme
Applications in Detergency and in Manufacturing Industries Pp. 1399-1422
Yves M. Galante and Cristina Formantici
Abstracts
[Back to top] Synthetic Applications of Nitrile-Converting Enzymes
Ludmila Martinkova and Veronika Mylerova
The use of nitrile hydratases (RCN + H2O
RCONH2) and nitrilases (RCN + 2 H2O RCOO- +
NH4+) in biocatalysis attracts profound attention from the beginning of 1980s
since it provides a useful alternative to the conventional nitrile hydrolysis
using strong acid or base catalysts. In the past 5 years the potential of this
branch of biotransformations has been broadened significantly by both the
isolation of new mesophilic and thermophilic nitrile-metabolizing
microorganisms and the purification of new nitrile-converting enzymes,
including thermostable ones. Currently, the scope of products afforded by
nitrile-converting biocatalysts encompass hundreds of compounds such as
aliphatic, alicyclic, aromatic and heterocyclic carboxylic acids and their
amides. New nitrile hydratases show high enantioselectivity towards racemic
substituted 2-arylpropionitriles, 2-arylbutyronitriles and prochiral
3-arylglutaronitriles. Synthesis of optically active -hydroxy and
-fluoro amides and acids employs whole-cell biocatalysts or purified
nitrilases. (E)-Selectivity for ,ß-unsaturated nitriles and cis- or
trans-selectivity for alicyclic nitriles is also demonstrated with some
nitrile-converting enzymes. Regioselectivity and chemoselectivity of the
biocatalysts enable preparation of diverse functional group-containing products
such as cyanocarboxylic acids, cyanoamides, hemiesters and their amides and
carboxylic acids and amides with ether groups. Stabilization of the
nitrile-converting biocatalysts is achieved by entrapment in hydrogels or by
lyophilization. Organic-aqueous mixtures are suitable as reaction media for
numerous nitrile-converting enzymes.
[Back to top] Properties and Synthetic Applications of Ammonia-Lyases
Laszlo Poppe and Janos Retey
Ammonia-lyases catalyze a wide range of processes leading
to ,-unsaturated compounds by elimination of ammonia having few
features in common. They utilize an extraordinary range of prosthetic groups;
e.g. coenzyme B12, dipyrromethane cofactor, pyridoxal-phosphate, or the
3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) prosthetic groups. In this
work, ammonia-lyases are reviewed with major emphasis on various aspects of
biotransformations, covering topics from the fundamental biochemistry of
ammonia-lyases to their structure determined by protein crystallography.
[Back to
top] Laccases and Phenol Oxidases in
Organic Synthesis – a Review
Stephanie G. Burton
This is a review of recent progress in developing
biocatalytic reactions involving two major groups of phenol oxidases, viz.,
laccases (benzenediol:oxygen oxidoreductase E.C. 1.10.13.2) and polyphenol
oxidases (phenol: oxygen oxidoreductase, E.C. 1.14.18.1, also known as
tyrosinase). Oxidases catalyse reactions involving direct activation of oxygen,
and within this group, the multi-copper oxidases catalyse the four-electron
reduction of oxygen to water with the concomitant one-electron oxidation of a
substrate. Such reactions, applied in biocatalytic systems, provide effective
methods to achieve oxyfunctionalisation, (particularly asymmetric
oxyfunctionalisation reactions) and routes to controlled and predictable
formation of oxy- and hydroxylated products, and polymers. The review includes
discussion of the characteristics of these enzymes which are of relevance to
their application as biocatalysts.
[Back to
top] Biocatalysis in Reaction Mixtures
with Undissolved Solid Substrates and Products
Rein V. Ulijn, Luigi De Martin, Lucia Gardossi and Peter
J. Halling
Enzymatic synthesis in reaction mixtures with mainly
undissolved substrates and/or products is a synthetic strategy in which the
compounds are present mostly as pure solids. It retains the main advantages of
conventional enzymatic synthesis such as high regio- and stereoselectivity,
absence of racemisation and reduced side-chain protection. The reaction yields
are improved and the necessity to use organic solvents to shift the
thermodynamic equilibrium toward synthesis is reduced by product precipitation,
which makes the synthesis favourable even in water.
The thermodynamics of these reaction systems have been
investigated in the last few years, resulting in methods to predict the
direction of a typical reaction a priori. Furthermore, studies on kinetics,
enzyme concentration, pH/temperature effects, mixing and solvent selection have
opened new perspectives for the understanding, modelling, optimisation and the
possible large scale application of such a strategy. In this review we have
tried to cover most of the literature published in the last five to ten years
on biocatalysis in substrate suspensions, focusing especially on cases where
the reaction products precipitate.
[Back to
top] Enzyme-Mediated Syntheses of Chiral Communication
Substances: Fragrances for Perfumery Applications
Elisabetta Brenna
This work describes the use of enzyme-mediated reactions
for the preparation of enantiomerically enriched chiral fragrances. The main
floral, musk and woody-ambery odorants employed in fine and functional
perfumery are taken into consideration.
[Back to
top] Microbial/Enzymatic Synthesis of Chiral Intermediates
for Pharmaceuticals:Case Studies from BMS
Ramesh N. Patel
There has been an increasing awareness of the enormous
potential of microorganisms and enzymes for the transformation of synthetic
chemicals with high chemo-, regio- and enatioselective manner. Chiral
intermediates are in high demand from pharmaceutical industries for the
preparation bulk drug substances. In this review article, microbial/enzymatic
processes mainly taken from the research carried out at BMS have been described
for the synthesis of chiral intermediates for antihypertensive drugs,
anticholesterol drugs, anticancer agents, antiviral agents, b3-receptor
receptor agonists, melatonin receptor agonists, and anti-Alzheimer's drugs.
[Back to
top] Enzymatic Synthesis of Polyphenols
Hiroshi Uyama and Shiro Kobayashi
In vitro synthesis of polyphenols using isolated enzymes
as catalyst via non-biosynthetic pathways is reviewed. Various phenols have
been subjected to an oxidative polymerization catalyzed by peroxidase, laccase,
or bilirubin oxidase under mild reaction conditions. In most cases, polyphenols
with a mixed structure of phenylene and oxyphenylene units have been formed. By
utilizing specific enzymatic catalysis, regio- and chemoselective polymerizations
have occurred, yielding functional and useful polymers, which are often
difficult to synthesize by conventional methodologies. Enzymatic curing of
urushiol analogues produces crosslinked polymeric films ("artificial
urushi") with high hardness and good elasticity.
[Back to
top] Enzyme Applications in Detergency and in Manufacturing
Industries
Yves M. Galante and Cristina Formantici
Applications of enzymes in industrial and food processes
have undergone remarkable developments in several areas in the last 10-20
years: detergent, textile, grain wet milling, food, monogastric animal feed,
pulp & paper, leather, natural polymer modifications, organic chemical
synthesis, diagnostics, etc.
Recombinant DNA technology and protein engineering are
currently the main technologies in the design and production of new industrial
enzymes, because they allow to reach high production yields of purified
products at competitive costs and to design new enzymes with novel properties
well adapted to industrial conditions.
Of the major classes of enzymes, about 80% of current
industrial enzymes are hydrolases (e.g., carbohydrolases, esterases) and are
extracellularly produced for ease of downstream recovery after fermentation. In
recent years, a few oxidoreductases have been commercially introduced (e.g.,
catalase, peroxidase, laccase) and even one lyase (pectate lyase for raw cotton
bioscouring).
In this review, we give an overview of enzyme applications
in: detergency, textile and leather, which are the three areas that represent
the majority of industrial enzyme uses.
In detergency, enzymes contribute to the highly efficient
removal of stains made of proteins, starch and grease from garments and
fabrics, thereby enhancing the action of surfactants and improving the
performance of the washing process.
In the textile industry, cellulases, amylases, proteases,
catalases, pectin lyase, peroxidase and laccase, have all become enzymes
commonly used in textile mills, dyehouses and industrial laundries.
In tanneries, application of proteases at the bating step
to soften the hides and prepare them for tanning has been a key step in leather
making ever since ancient times. A vast range of proteases is now available for
soaking, bating and for unhairing raw hides, and of lipases for degreasing.