Fibrin-dependent activation of plasminogen by a proteolytic digest of streptokinase.
Among four enzymatic digests of streptokinase (SK), the smallest peptide with plasminogenolytic activity was in a tryptic digest; it had a molecular weight of 29,000. A complex of this peptide, SK29, and human plasminogen hydrolysed human fibrin, but a complex of native streptokinase and human plasminogen hydrolysed both human and bovine fibrin. The complex with SK29 caused amidolysis of the synthetic substrate S-2251 in the presence of human fibrin, but was inactive in the presence of human fibrinogen, bovine fibrinogen or bovine fibrin. Analysis of the amino terminal sequence of SK29 indicated that cleavage by trypsin was on the carboxyl side of lysine, the 59th amino acid of streptokinase. These results suggest that the conformational changes caused by human fibrin formation resulted in the generation of an active site of human plasminogen by SK29.
Nakashima
A
A
Department of Physiology, Aichi Medical University, Japan.
Okada
T
T
Sugie
I
I
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D005337:Fibrin / Q000378:metabolism / Q000494:pharmacology*; D005340:Fibrinogen / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D011487:Protein Conformation; D013300:Streptokinase / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014357:Trypsin / Q000378:metabolism
D010446:Peptide Fragments; D005337:Fibrin; D005340:Fibrinogen; D010958:Plasminogen; D013300:Streptokinase; D014357:Trypsin