Corfield A P, Wagner S A, O'Donnell L J, Durdey P, Mountford R A, Clamp J R
University Department of Medicine, Bristol Royal Infirmary, UK.
Glycoconj J. 1993 Feb;10(1):72-81. doi: 10.1007/BF00731190.
Sialidase activity in normal faecal extracts showed a preference for mucin-related glycoprotein and oligosaccharide substrates, but the presence of two or more O-acetyl esters at positions C7-C9 on the sialic acids retarded the rate of hydrolysis. A specific sialate O-acetyl esterase was detected with a lower total activity relative to sialidase with mucin substrates and having a pH optimum of 7.8 and a KM of approximately 1 mM sialate O-acetyl ester. A specific glycosulfatase activity was found in faecal extracts using the substrate lactit-[3H]ol 6-O-sulfate with a pH optimum of pH 5.0 and a KM of approximately 1 mM. Faecal extracts from ulcerative colitis (UC) patients had higher sialate O-acetyl esterase and glycosulfatase activity, while mucin sialidase activity was unchanged. Metabolically labelled mucin isolated from UC patients contained less sulfate and had lower sialic acid O-acetylation compared with normal mucin. Colonic mucin was degraded more efficiently by faecal extracts from UC patients compared with normal extracts. The UC mucin was degraded more rapidly than the normal mucin by faecal enzyme extracts from both normal and UC subjects.
正常粪便提取物中的唾液酸酶活性对黏蛋白相关糖蛋白和寡糖底物表现出偏好，但唾液酸C7 - C9位存在两个或更多O - 乙酰酯会减缓水解速率。检测到一种特异性唾液酸O - 乙酰酯酶，相对于以黏蛋白为底物的唾液酸酶，其总活性较低，最适pH为7.8，对唾液酸O - 乙酰酯的米氏常数约为1 mM。使用底物乳糖 - [3H]醇6 - O - 硫酸盐在粪便提取物中发现了一种特异性糖硫酸酯酶活性，最适pH为5.0，米氏常数约为1 mM。溃疡性结肠炎（UC）患者的粪便提取物中唾液酸O - 乙酰酯酶和糖硫酸酯酶活性较高，而黏蛋白唾液酸酶活性未变。与正常黏蛋白相比，从UC患者分离的代谢标记黏蛋白含有的硫酸盐较少，唾液酸O - 乙酰化程度较低。与正常提取物相比，UC患者的粪便提取物能更有效地降解结肠黏蛋白。正常人和UC患者的粪便酶提取物对UC黏蛋白的降解速度均比正常黏蛋白快。
