Chi C W, Zhu D X, Lin N Q, Xu L X, Tan F L, Wang L X
Biol Chem Hoppe Seyler. 1985 Sep;366(9):879-85. doi: 10.1515/bchm3.1985.366.2.879.
After reduction and alkylation of the disulfide bonds of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.) followed by CNBr cleavage three peptide fragments with 68, 62 and 11 amino-acid residues could be separated on DEAE-Sepharose CL-6B. The peptides or the inhibitor itself were further specifically cleaved either by trypsin or by the mixture of (CH3)2SO/HCl/HBr at the arginyl- and the tryptophyl-peptide bond, respectively. The complete amino-acid sequences of the peptides were determined by manual solid phase DABITC/PITC double coupling micro-method and the primary structure of the arrowhead inhibitor B consisting of 141 amino-acid residues was then elucidated. Twenty pairs of amino-acid residues are repeated in the molecule of this inhibitor, three of these pairs even occur three times. The possible locations of the reactive sites are discussed. On the basis of sequence comparisons between this inhibitor and all other serine proteinase inhibitors the arrowhead inhibitor may belong to a new family.
对慈姑（Sagittaria sagittifolia L.）根部的蛋白酶抑制剂B的二硫键进行还原和烷基化处理后，通过溴化氰裂解，可在DEAE-琼脂糖CL-6B上分离出具有68、62和11个氨基酸残基的三个肽片段。肽或抑制剂本身再分别用胰蛋白酶或(CH3)2SO/HCl/HBr混合物在精氨酰肽键和色氨酰肽键处进行特异性裂解。通过手工固相DABITC/PITC双偶联微方法测定了肽的完整氨基酸序列，进而阐明了由141个氨基酸残基组成的慈姑抑制剂B的一级结构。该抑制剂分子中有20对氨基酸残基重复出现，其中三对甚至出现了三次。讨论了活性位点的可能位置。基于该抑制剂与所有其他丝氨酸蛋白酶抑制剂之间的序列比较，慈姑抑制剂可能属于一个新家族。
