Identification of the proteolytic thrombin fragments formed after cleavage with rat mast cell protease 1.
We have previously identified rat mast cell protease 1 (RMCP-1), a chymotrypsin-like secretory granule serine protease, as a potent inactivator of thrombin. The present study outlines the cleavage pattern obtained after degradation of thrombin by RMCP-1. The cleavage sites in thrombin were identified by N-terminal amino acid sequence analysis of recovered thrombin fragments. Incubation of thrombin with RMCP-1 resulted in the rapid formation of a 37-kDa fragment, due to cleavage of the Phe1G-Gly1F bond in the thrombin A chain (numbering of amino acid residues according to topological equivalencies with chymotrypsinogen). Further incubation resulted in cleavage of the Trp148-Thr149 bond in the B chain, along with the formation of fragments of 27 kDa and 15 kDa. When the RMCP-1/thrombin mixtures were incubated further, successive degradation of the 37-kDa, 27-kDa and 15-kDa fragments was observed, along with cleavage of the Tyr117-Ile118 bond in the B chain and the formation of fragments of 12, 9 and 6 kDa. No residual thrombin activity was detected after the degradation process had proceeded to this stage. Heparin was shown to markedly enhance the rate of thrombin degradation by RMCP-1.
Swedish University of Agricultural Sciences, Dept. of Veterinary Medical Chemistry, Uppsala.
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Pejler
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Karlström
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Berg
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D053818:Chymases; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D051381:Rats; D012697:Serine Endopeptidases / Q000378:metabolism*; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism
D010446:Peptide Fragments; D012697:Serine Endopeptidases; D053818:Chymases; C509231:Mcpt1 protein, rat; D013917:Thrombin