期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：20
页码：6132-6136
DOI：10.1073/pnas.79.20.6132
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Structural studies on a hereditarily abnormal plasminogen, plasminogen Tochigi, have been performed to identify the difference responsible for its lack of proteolytic activity. The plasminogen sample used was from a heterozygote and thus consisted of apparently equal amounts of normal and defective plasminogen molecules. Amino acid sequence analysis of a tryptic peptide isolated from the abnormal plasminogen indicated that Ala-600 (equivalent to Ala-55 in the chymotrypsin numbering system) had been replaced by Thr. No other substitutions in the active-site residues--namely, His-57, Asp-102, and Ser-195--were found. Molecular models for chymotrypsin and the bovine trypsin-pancreatic trypsin inhibitor complex indicate that Ala-55 is very near the active-site His. The Thr at position 55 in plasminogen (plasmin) Tochigi may perturb His-57 such that the proton transfers associated with the normal catalytic process cannot occur in the abnormal plasmin.
