Industrial Biotransformations

2.2 Enzyme Classes
Three of the only four enzymes in this subclass depend on thiamin-diphosphate as a
cofactor. The catalyzed reactions can be regarded as an aldol addition. Some enzymes
also accept hydroxypyruvate as a donor to form CO 2 and the resulting addition product.
EC 2.3 Acyltransferases
R 1 X 1
O
R 2
+
R 3 X 2 H R 3 X 2
X +
1 R H
1
X 1 = S, O, NH
X 2 = S, O, NH, CH2 R 1 = hydrogen, alkyl-, aryl- or monophosphate residue
R 2 = hydrogen, alkyl- or aryl-residue
R 3 = alkyl-, aryl-, acyl- or monophosphate residue, aryl-NH
Transferred acyl-groups are often activated as coenzyme A (CoA) conjugates.
EC 2.4 Glycosyltransferases
HO
HO
OH
O
X 1 = O, PO 4 3-
OH
+
X 1 1 R2
R
R 1
X 2 H X 1 H
X 2 = O, NH
R 1 = hydrogen, hexosyl, pentosyl, oligosaccharide, monophosphate
R 2 = hexosyl, pentosyl, oligosacharide, monophosphate, organic residue with OH- or NH2-groups X 1 R 1 = nucleoside di- or monophosphates (e.g. UDP, ADP, GDP or CMP), purine
This enzyme subclass is subdivided into the hexosyl- (sub-subclass 2.4.1) and pentosyltransferases
(sub-subclass 2.4.2). Although a hexosyl transfer is illustrated in the figure,
this general scheme is intended to describe both enzyme sub-subclasses.
+
HO
O
R 2
HO
OH
O
OH
X 2 R 2
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