Industrial Biotransformations

84
3 Retrosynthetic Biocatalysis
3.21
Cyclic Compounds
O
X
X R'
R H
X= O, CH 2
monooxygenase
cyclase
lyase
Lactones can be formed from ketones under enzymatic Baeyer–Villiger reaction conditions
[58], or enzymatic macrocyclization, commonly seen in the biosynthesis of natural
products, where the hetero atom X can be oxygen, nitrogen [59].
Intramolecular lyases can give similar products [60].
3.22
Carbohydrates
glycosyltransferase
sugar-XR sugar-OUTP (or TDP) + RXH
X = O, S, NH, C -
glycosidase
sugar1-sugar2 sugar1-OH + X-sugar2
X = p-nitrophenyl, halo
There are many glycosyltransferases available for the synthesis of carbohydrates. The
nucleophiles can be alcohol (the most common type), thiol, amine or even carbanions.
The reversal hydrolytic reactions are catalyzed by glycosidases [61]. When activated sugars
are used, disaccharides can be prepared on a large scale by glycosidases.
XH
R
O
O
SR
X
H
R'