Ap. Corfield et al., THE ROLES OF ENTERIC BACTERIAL SIALIDASE, SIALATE O-ACETYL ESTERASE AND GLYCOSULFATASE IN THE DEGRADATION OF HUMAN COLONIC MUCIN, Glycoconjugate journal, 10(1), 1993, pp. 72-81
Sialidase activity in normal faecal extracts showed a preference for m
ucin-related glycoprotein and oligosaccharide substrates, but the pres
ence of two or more O-acetyl esters at positions C-7-C-9 on the sialic
acids retarded the rate of hydrolysis. A specific sialate O-acetyl es
terase was detected with a lower total activity relative to sialidase
with mucin substrates and having a pH optimum of 7.8 and a K(M) of app
roximately 1 mM sialate O-acetyl ester. A specific glycosulfatase acti
vity was found in faecal extracts using the substrate lactit-[H-3]ol 6
-O-sulfate with a pH optimum of pH 5.0 and a K(M) of approximately 1 m
M. Faecal extracts from ulcerative colitis (UC) patients had higher si
alate O-acetyl esterase and glycosulfatase activity, while mucin siali
dase activity was unchanged. Metabolically labelled mucin isolated fro
m UC patients contained less sulfate and had lower sialic acid O-acety
lation compared with normal mucin. Colonic mucin was degraded more eff
iciently by faecal extracts from UC patients compared with normal extr
acts. The UC mucin was degraded more rapidly than the normal mucin by
faecal enzyme extracts from both normal and UC subjects.