Hoskins L C, Boulding E T
J Clin Invest. 1976 Jan;57(1):63-73. doi: 10.1172/JCI108270.
Human feces contain enzymes produced by enteric bacteria that degrade the A, B, and H blood group antigens of gut mucin glycoproteins. We have studied their production in fecal cultures to determine if such cultures can be a source for enzyme purification and to explore how blood group antigen-degrading enzymes are adapted in individual human colon ecosystems. They were present in fecal cultures from each of 27 healthy subjects, including ABH nonsecretors. Heat-sensitive obligate anaerobes are their major source. From 39 to 85% of the total enzyme activity produced by growing cultures was extracellular. Commercial hog gastric mucin and salivary glycoproteins, including Lea saliva which lacks A, B, and H antigens, enhance production of A-, B-, and H-degrading activity in anaerobic fecal cultures irrespective of the glycoprotein's blood group specificity. There is evidence that the host's ABO blood type and secretor status affects the specificity of blood group-degrading enzymes produced by his fecal bacteria in vitro. Thus, fecal inocula from B secretors incubated with hog gastric mucin (A and H specificity) or with Lea saliva produced greater levels of B-degrading than A- or H-degrading activity, and inocula from A secretors in similar media produced greater levels of A-degrading than B- or H-degrading activity. Blood group-degrading enzymes produced in fecal cultures are glycosidases and not proteases. The B-degrading enzyme cleaves the B antigenic determinant alpha-D-galactose from the oligosaccharide side chains of mucin glycoproteins with B specificity. Anaerobic fecal cultures containing blood group substances are a feasible source for purifying blood group antigen-degrading enzymes. Prior adaptation to blood group antigens in the gut mucins of type A and type B secretors affects the specificity of the enzymes produced in vitro.
人类粪便中含有肠道细菌产生的酶，这些酶可降解肠道粘蛋白糖蛋白的A、B和H血型抗原。我们研究了它们在粪便培养物中的产生情况，以确定此类培养物是否可作为酶纯化的来源，并探索血型抗原降解酶在个体人类结肠生态系统中的适应性。它们存在于27名健康受试者（包括ABH非分泌者）的粪便培养物中。热敏性专性厌氧菌是其主要来源。生长培养物产生的总酶活性中有39%至85%是细胞外的。商业猪胃粘蛋白和唾液糖蛋白，包括缺乏A、B和H抗原的Lea唾液，无论糖蛋白的血型特异性如何，均可增强厌氧粪便培养物中A、B和H降解活性的产生。有证据表明，宿主的ABO血型和分泌状态会影响其粪便细菌在体外产生的血型降解酶的特异性。因此，与猪胃粘蛋白（A和H特异性）或Lea唾液一起孵育的B分泌者的粪便接种物产生的B降解活性水平高于A或H降解活性，而在类似培养基中A分泌者的接种物产生的A降解活性水平高于B或H降解活性。粪便培养物中产生的血型降解酶是糖苷酶而非蛋白酶。B降解酶从具有B特异性的粘蛋白糖蛋白的寡糖侧链上切割下B抗原决定簇α-D-半乳糖。含有血型物质的厌氧粪便培养物是纯化血型抗原降解酶的可行来源。先前在A和B型分泌者的肠道粘蛋白中对血型抗原的适应会影响体外产生的酶的特异性。
