Most commonly used biocatalytical transformations
Name
Scheme
Key info
Cofactor:
RED = multiple enzymes, or rarely used
GREEN = commonly used, no second enzyme
BLUE = not required, no additional enzyme
required
Substrate scope:
GREEN (broad scope) to RED (specific)
Hydrolase
R, R’, R” can be asymm centers, often used for kinetic resolutions and desymmetrizations. When immobilized can tolerate organic solvents.
Ketoreductase
R- and S-selectivities available. Dynamic kinetic resolutions possible within R’ and R” groups. Eqm usually favors alcohol product. Can run in oxidative direction.
Transaminase
Iminereductase
Asymmetric intermolecular reductive amination with IRED and RedAm. Some IRED only acitive on preformed imines
Enereductase
Trans reduction of the alkene. Selectivity can be engineered, steric crowding generally poorly tolerated. Eqm requires driving
Nitrilase
Irreversible conversion of nitrile to acid (enzymes that convert nitrile to amide are nitrile hydratases).Used in kinetic resolutions or chemoselective hydrolysis of one nitrile over another.
Aldolase
Several classes of aldolase, e.g.DERA (deoxyribose aldolase), others such as pyruvate and fructose aldolase also known.
Amino acid dehydrogenase
Most commonly used in the ‘reverse’ direction to form novel amino acids. R and S selective enzymes available. Deracemization of amines when coupled to compatible chemical reductant.
aKG dependent dioxygenase
Non-heme Fe(II)- and a-ketoglutaratedependent enzymes using O as oxidant. Ascorbic acid generally required. Enzymes available for regio- and stereoselective hydroxylation of cyclic as well as acyclic amino acids. Non-amino acids can also be substrates.
Ammonia lyase
PAL phenylalanine ammonia lyase, TAL tyrosine ammonia lyase most commonly used but others available. Used in the amino acid forming direction with very high ammonia concentrations to drive equilibrium.
Baeyer-Villiger monooxygenase
Asymmetric BV reaction, asymmetric sulfide oxidation to sulfoxide.
Hydroxynitrile lyase
Catalyze the formation and hydrolysis of a-hydroxy nitriles from/to aldehydes and cyanide. Used in a commercial approach to mandelic acid.
NItrile hydratase
Irreversible conversion of nitrile to amide (enzymes that convert nitrile to acid are nitrilases). Kinetic or dyamic resolution possible with enolisable proton.
Epoxide hydrolase
Irreversible conversion of epoxide to diol. Mostly used for kinetic resolution (KR). Some EHs are stereoconvergent (SC), ie convert a racemic epoxide to single enantiomer diol. Different mechanistic classes exist.
Monoamine oxidase
Desymmetrization of pyrrolidines, and trap of imine. Primary amine oxidation. Deracemization of amines when coupled to compatible chemical reductant.
Alcohol oxidase
Many sub-types with different substrate selectivities.eg galactose oxidase (GO) acts on primary alcohols in polyols and benzylic alcohols. Kinetic resolutions possible. Oxygen mass transfer limited.
Halohydrin dehalogenase
Catalyze the conversion of vicinal halohydrins to epoxides, as well as epoxide ring opening. Closely related to some epoxide hydrolases.
Unspecific peroxygenase
Fungal heme containing enzymes use hydrogen peroxide as oxidant and require no cofactors. They have varying oxidative capabilities including:
Hydroxylation, epoxidation, N- or S- oxidation, bromination, dealkylation
Tryptophan synthase
Native reaction forms L-tryptophan using PLP cofactor. Many non-canonical amino acids have been produced with engineered variants.
Carboxylic acid reductase
Multidomain enzyme that uses ATP to transform the carboxylic acid to a thioester, and then reduces the thioester to the aldehyde with NADPH.
Halogenase
Halogenation of aromatic rings. Halogenation takes place via a halogenated lysine residue. Regiochemistry can be controlled via directed evolution of the enzyme.
Cytochrome P450
Heme containing enzyms using oxygen as oxidant.Requires electron transfer proteins either as part of the enzyme or added enzymes, often nicotinamide dependent. They have varying oxidative capabilities including:
Hydroxylation, desaturation, epoxidation, N- or S-oxidation, dealkylation
Amide ligase
ATP dependent amide formation between acid and amine.
Nicotinamide cofactor recycling
Most commonly used reductive nicotinamide regenerating systems
Nicotinamide Cofactor Recycling
Glucose dehydrogenase
Gluconic acid formation drops reaction pH, and may required the use of a pH stat. Highly active enzyme. Active on both NAD+ and NADP+.
Ketoreductase
Formate dehydrogenase
Less commonly used reductive nicotinamide regenerating systems
Phosphite dehydrogenase
Enereductase
NAD(P)H oxidase
For oxidative approaches
Irreversible conversion of reduced co-factor to oxidized cofactor in presence of O2. NADH or NADPH activity available. Sacrifical substrate approach (similar to KRED + IPA). Use unsaturated donor that can aromatize when oxidized.
Non-enzymatic methods
Electrochemical
Potentially the ‘greenest’ approach, still in development.
Photochemical
Still in development.
Non-abundant metal hydrogenation
Still in development, but questionable sustainability.
Adenosine triphosphate (ATP) recycling
Most commonly used ATP regenerating systems
Acetate kinase
Polyphosphate kinase
Phosphoenolpyruvate kinase
Adenylate kinase
Guanylate kinase
Less commonly used ADP/ATP regenerating systems
Adenosine Triphosphate (ATP) Recycling
Creatine phosphate kinase
Polyphosphate transferase
