The preparation of biotin-labelled hyaluronidase

Centre and purified using the appropriate Synsorbs (Chembiomed Ltd., Alberta, Canada). Monoclonal anti-A was isolated in the M.R.C. Human Biochemical Genetics Unit. In one experiment lactase from two individuals of different blood group (A and 0) was purified by immunoaffinity chromatography as described in Potter et al. (1985). Using the A blood-group specific antibodies and the lectin from Helix pomutiu we have shown that many different glycoproteins from five A secretors, one AB secretor and one (out of four) apparent A non-secretors carry abundant A antigen, and that the antigen is specifically carried on lactase, sucrase and aminopeptidase. Likewise the anti-B serum and the lectin from Bandeiraea sirnplic$olia (BS 1 ) reveal that the B antigen is carried on the glycoproteins of all seven B secretors and the one AB secretor tested, and can be demonstrated specifically on the lactase, sucrase and aminopeptidase. No B non-secretors were available for study. Using anti-H serum and the lectin from Wlex europeaus, quantitative differences could be seen in the H antigen detected on these glycoproteins in secretors and non-secretors but this was less clear cut. Similar experiments in progress with anti-Lewis antibodies show that Le" and/or Le" are carried on this group of glycoproteins and can be specifically detected on sucrase, lactase and aminopeptidase. The presence of the Lewis antigens on the glycoproteins of the samples so far tested appears also to depend on the ABO, Lewis and secretor types of the individuals as expected. Thus our results confirm those of Triadou et ul. (1983) that the ABH antigens are structural determinants on the brush-border hydrolases of the human small intestine. This expression also appears to be dependent upon the secretor status, although there was one exception, an individual whose brush-border hydrolases carry the A determinant despite the lack of a-2-fucosyltransferase activity in the jejunum and their non-secretor status as judged by stomach mucus. This discrepancy is not easily explained by the quality of the post-mortem tissue, particularly since the levels of the a-3-~-acetylgalactosaminyltransferase and a-3-fucosyltransferase were both high. I t is known that the presence of the H antigen in certain human intestinal cells is not under the control of the Se gene (Mollicone et al., 1986) and it is possible that a-2-fucosyltransferase activities are present in the human gut which are not detectable by our standard assay procedures. I t is intriguing but possibly coincidental that this exceptional individual was also Lewis negative. Although jejunal aminopeptidase carries the ABH and Lewis determinants, aminopeptidase from kidney, which is a closely related enzyme, and probably a product of the same gene locus, does not. It is noteworthy that the overall level of a-2-fucosyltransferase in kidney is low in comparison with jejunum, suggesting that this enzyme may not be expressed within the cells responsible for the synthesis of aminopeptidase.