Magee A I, Grant D A, Taylor J H
Clin Chim Acta. 1981 Sep;115(3):241-54. doi: 10.1016/0009-8981(81)90238-2.
Highly purified human enterokinase was found by SDS-polyacrylamide gel electrophoresis to contain three heavily glycosylated subunits of apparent molecular masses 54 000, 102 000 and 140 000. The smallest subunit contained the active site serine residue and the oligosaccharide chains appear to be N-glycosidically linked as inferred from their stability to mild alkaline hydrolysis. Lectin affinity chromatography was used to separate sub-populations of the enzyme, the major one of which appeared to contain terminal alpha -linked N-acetyl galactosamine. Despite the presence of this sugar, no anti-A response was elicited in rabbits immunized with this sub-population. However, this sub-population did bind rabbit antibody directed against human blood group A substance, suggesting the presence of an "A-like" determinant. Studies with immobilized rabbit anti-human blood group A IgG suggest that there is no correlation between the blood group of an individual and the antigenic determinants on the enterokinase produced by the enterocytes of that individual. The study of the molecular properties of this important enzyme may give insights into pathological conditions with which it is linked.
通过SDS-聚丙烯酰胺凝胶电泳发现，高度纯化的人肠激酶含有三个明显糖基化的亚基，表观分子量分别为54000、102000和14000。最小的亚基含有活性位点丝氨酸残基，从其对温和碱性水解的稳定性推断，寡糖链似乎是通过N-糖苷键连接的。凝集素亲和层析用于分离该酶的亚群，其中主要亚群似乎含有末端α-连接的N-乙酰半乳糖胺。尽管存在这种糖，但在用该亚群免疫的兔子中未引发抗A反应。然而，该亚群确实结合了针对人血型A物质的兔抗体，表明存在“类A”决定簇。用固定化兔抗人血型A IgG进行的研究表明，个体的血型与该个体肠细胞产生的肠激酶上的抗原决定簇之间没有相关性。对这种重要酶的分子特性的研究可能有助于深入了解与之相关的病理状况。
