Baramova E N, Shannon J D, Fox J W, Bjarnason J B
Department of Microbiology, University of Virginia Medical School, Charlottesville 22908.
Biomed Biochim Acta. 1991;50(4-6):763-8.
Hemorrhagic toxin e (Ht-e), a metalloproteinase isolated from the venom of the Western Diamondback rattlesnake Crotalus atrox, digests laminin and nidogen, both in their isolated forms and when present in a purified soluble complex. The only common site of cleavage by Ht-e of isolated nidogen and nidogen when complexed with laminin is at amino acid residue 336 in the amino terminal domain. Additionally, nidogen in complex with laminin is also cleaved at sites 322, 351 and 840 as determined by sequence analysis and site 953 as proposed from the molecular mass of a digestion product. Isolated nidogen, on the other hand, was cleaved at amino acid residues 75, 336, 402, and 920, as determined by sequence determinations and approximately at residues 296, 478, 625 and 702 as proposed from the molecular mass values of the generated polypeptide chains. Products from the proteolytic cleavage of the A and B2 chains of laminin were observed with the sites of cleavage determined to be at position 2666 in the laminin A chain and position 1238 in the laminin B2 chain. The laminin digestion products were identical regardless of whether nidogen was present in a complex with the laminin chains.
出血毒素e（Ht-e）是一种从西部菱斑响尾蛇（Crotalus atrox）毒液中分离出的金属蛋白酶，它能分解层粘连蛋白和巢蛋白，无论是它们的分离形式，还是存在于纯化的可溶性复合物中时。Ht-e对分离的巢蛋白以及与层粘连蛋白复合时的巢蛋白进行切割的唯一共同位点，是氨基末端结构域中的氨基酸残基336。此外，通过序列分析确定，与层粘连蛋白复合的巢蛋白在322、351和840位点也会被切割，根据一种消化产物的分子量推测，在953位点也会被切割。另一方面，通过序列测定确定，分离的巢蛋白在氨基酸残基75、336、402和920处被切割，根据生成的多肽链的分子量推测，大约在296、478、625和702残基处被切割。观察到层粘连蛋白A链和B2链的蛋白水解切割产物，切割位点确定为层粘连蛋白A链中的2666位和层粘连蛋白B2链中的1238位。无论巢蛋白是否与层粘连蛋白链形成复合物，层粘连蛋白的消化产物都是相同的。
