The biosynthetic pathway of 3-amino-5-hydroxybenzoic acid (AHBA) formation was studied with cell-free extracts from the rifamycin B producer, Amycolatopsis mediterranei S699, and the ansatrienin A producer, Streptomyces collinus Tü1892. Phosphoenolpyruvate (PEP) plus erythrose 4-phosphate (E4P) gave AHBA in low but nevertheless significant (6%) yield. 3,4-Dideoxy-4-amino-d-arabino-heptulosonic acid 7-phosphate (aminoDAHP) was converted efficiently into AHBA (45%), as were 5-deoxy-5-amino-3-dehydroquinic acid (aminoDHQ, 41%) and 5-deoxy-5-amino-3-dehydroshikimic acid (aminoDHS, 95%). On the other hand, the normal shikimate pathway intermediate, 3-deoxy-d-arabino-heptulosonic acid 7-phosphate (DAHP) did not give rise to AHBA under these conditions. AminoDAHP (9%) was produced by incubation of [14C]PEP and E4P, but not of [14C]DAHP, with the cell-free extracts. The results demonstrate the operation of a new variant of the shikimate pathway in the formation of the mC7N units of ansamycin, and presumably also mitomycin, antibiotics which leads from PEP, E4P, and a nitrogen source directly to aminoDAHP and then via aminoDHQ and aminoDHS to AHBA.

A series of sialyloligosaccharides was synthesized using the transglycolytic activity of the sialidases from Vibrio cholerae, Clostridium perfringens, Salmonella typhimurium, and Newcastle disease virus. According to their hydrolytic activities the sialidases from V. cholerae and C. perfringens catalyze preferentially the formation of sialyl alpha(2-6)-linkages whereas the sialidases from S.typhimurium and Newcastle disease virus show a distinct preference for alpha(2-3) directed sialylations. Using combined chemical and enzymatic methodologies structures such as T-(Thomsen-Friedenreich) antigen [beta-D-Gal-(1-3)-alpha-D-GalNAc-OThr], Tn-(Thomsen nouveau) antigen (alpha-D-GalNAc-OThr) and beta-D-Gal-(1-4)-alpha-D-2-deoxy-Gal-OMe were sialylated in alpha(2-3)- and alpha(2-6)-positions regioselectively or in high regioisomeric excess and purified by simple isolation procedures. Depending on the enzyme source and acceptor structure yields for transsialylation varied between 10 and 30%.

The α‐glycosidic transfer of N‐acetylneuraminic acid (Neu5Ac) to the terminally bound galactose of the acceptor molecule is achieved with immobilized sialidase obtained from Vibrio cholerae. This is the first application of this enzyme in the catalysis of transglycosylation, which produces (2–6)‐ and (2–3)‐linked sialyloligosaccharides. These molecules often cannot be prepared by feasible synthetic methods, yet their physiological importance in glycoproteins and ‐lipids continue to generate interest.

Lipases and esterases can be used to fragment the 4-acetyloxybenzyloxy group used as a linker for organic synthesis on solid supports. (A support-bound compound is shown on the right; the enzyme-labile bond is marked with an arrow.) This enzyme-initiated fragmentation proceeds under very mild conditions (pH 6-7, room temperature), and the compounds of interest (amines, alcohols, carboxylic acids; X=NH, O, CR ) constructed by combinatorial chemistry can be released with complete selectivity.