Aird S D, Kaiser I I, Lewis R V, Kruggel W G
Arch Biochem Biophys. 1986 Sep;249(2):296-300. doi: 10.1016/0003-9861(86)90005-6.
The complete amino acid sequence of the basic subunit of crotoxin from the venom of Crotalus durissus terrificus has been determined. Fragmentation of the protein was achieved by using cyanogen bromide and arginine- and lysine-specific endoproteases. Sixteen Glx and Asx residues reported by Fraenkel-Conrat et al. (1980) in Natural Toxins (D. Eaker and T. Wadstrom, eds.), pp. 561-567, Pergamon, Oxford.) have been resolved as Glu or Gln and Asp or Asn residues, respectively. Most of the remaining sequence is identical to that reported by the foregoing authors although several significant differences were evident in our protein. Tyr-61 was not present; thus the correct sequence is Lys-60, Trp-61. The latter sequence aligns with sequences of all other known viperid and crotalid phospholipases A2 (S. D. Aird, I. I. Kaiser, R. V. Lewis, and W. G. Kruggel (1985) Biochemistry 24, 7054-7058). Other differences include Asx-99, which is Ser, and Asx-105, which is Tyr. Some positions display allelic variation. In some lots of venom Glx-33 is Gln, while in others it is Arg. Positions 37 and 69 occur as mixtures of both Lys and Arg. Amino acid sequence comparisons between the basic and acidic subunits of crotoxin and between the basic subunit and other phospholipase A2 molecules indicate that the basic subunit is structurally most similar to the monomers of nontoxic, dimeric phospholipases A2 from the venoms of Crotalus adamanteus, Crotalus atrox, and Trimeresurus okinavensis, and to the toxic monomeric phospholipase A2 from the venom of Bitis caudalis.
已确定了来自巴西矛头蝮蛇毒液的响尾蛇毒素碱性亚基的完整氨基酸序列。通过使用溴化氰以及精氨酸和赖氨酸特异性内切蛋白酶实现了该蛋白质的片段化。Fraenkel-Conrat等人（1980年，载于《天然毒素》（D. Eaker和T. Wadstrom编），第561 - 567页，Pergamon出版社，牛津）报告的16个Glx和Asx残基已分别解析为Glu或Gln以及Asp或Asn残基。其余大部分序列与上述作者报告的序列相同，尽管我们的蛋白质中存在一些明显的显著差异。不存在Tyr - 61；因此正确序列是Lys - 60，Trp - 61。后一序列与所有其他已知蝰蛇科和响尾蛇科磷脂酶A2的序列一致（S. D. Aird、I. I. Kaiser、R. V. Lewis和W. G. Kruggel（1985年）《生物化学》24，7054 - 7058）。其他差异包括Asx - 99为Ser，Asx - 105为Tyr。一些位置存在等位基因变异。在一些毒液批次中，Glx - 33是Gln，而在其他批次中是Arg。第37和69位出现Lys和Arg的混合物。响尾蛇毒素碱性和酸性亚基之间以及碱性亚基与其他磷脂酶A2分子之间的氨基酸序列比较表明，碱性亚基在结构上与来自钻石背水蛇、西部菱斑响尾蛇和冲绳竹叶青蛇毒液的无毒二聚体磷脂酶A2的单体以及来自尾具咝蝰蛇毒液的有毒单体磷脂酶A2最为相似。
