DETECTION OF A GENETIC VARIANT, LYSINE-]GLUTAMIC ACID AT POSITION-372OF HUMAN SERUM-ALBUMIN, BY CAPILLARY ELECTROPHORESIS AND STRUCTURAL IDENTIFICATION

A genetic variant of human serum albumin (alloalbumin) is detected by capillary electrophoresis (CE). Two albumin peaks, which were in the r atio of approximately one, were clearly separated. One of the peaks ha d the same migration time as normal albumin (Alb A) and the other (Alb X) had a longer migration time. SDS-polyacrylamide gel electrophoresi s of CNBr fragments (CB) of Alb X indicated that the amino acid substi tution was localized in the CB5 fragment (residue 330-446) of the mole cule, because of anomalous migration of CB5 in the gel. The CE mapping of the tryptic peptides from the variant CB5 revealed clearly the exi stence of a new peptide, and the lack of two normal peptides. The sequ ence analysis of the variant peptide collected by CE micropreparation showed that the N-terminus of the variant peptide corresponded to that of T49 in Alb A. The substitution site, lysine-->glutamic acid at the position 372, was revealed by sequence determination of the variant p eptide purified by reversed-phase HPLC. (C) 1997 Elsevier Science B.V.