Valueva T A, Revina T A, Mosolov V V, Mentele R
Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow.
Biol Chem. 2000 Dec;381(12):1215-21. doi: 10.1515/BC.2000.149.
The serine proteinase inhibitor (PSPI-21) isolated from potato tubers (Solanum tuberosum L.) comprises two protein species with pI 5.2 and 6.3, denoted as PSPI-21-5.2 and PSPI-21-6.3, respectively. They were separated by anion exchange chromatography on a Mono Q FPLC column. Both species tightly inhibit human leukocyte elastase, whereas their interaction with trypsin and chymotrypsin is substantially weaker. The sequences of both PSPI-21-5.2 and PSPI-21-6.3 were determined by analysis of overlapping peptides obtained from the oxidized or reduced and S-pyridylethylated proteins after digestion with trypsin or pepsin. Both species of PSPI-21 are composed of two chains, named chains A and B, which are linked by a disulfide bridge between Cys(146) and Cys(157). The other disulfide bridge is located within the A chains between Cys(48) and Cys(97). The amino acid sequences of the large A chains of the two forms, consisting of 150 amino acids residues each, differ in a single residue at position 52. The small chains B, containing 37 and 36 residues in PSPI-21-6.3 and PSPI-21-5.2, respectively, have nine different residues. The entire amino acid sequences of the two inhibitors show a high degree of homology to the other Kunitz-type proteinase inhibitors from plants.
从马铃薯块茎（茄属马铃薯）中分离出的丝氨酸蛋白酶抑制剂（PSPI - 21）包含两种蛋白质，其等电点分别为5.2和6.3，分别表示为PSPI - 21 - 5.2和PSPI - 21 - 6.3。它们通过在Mono Q FPLC柱上的阴离子交换色谱法分离。这两种蛋白质都能紧密抑制人白细胞弹性蛋白酶，而它们与胰蛋白酶和胰凝乳蛋白酶的相互作用则弱得多。PSPI - 21 - 5.2和PSPI - 21 - 6.3的序列是通过分析用胰蛋白酶或胃蛋白酶消化后的氧化或还原及S - 吡啶基乙基化蛋白质得到的重叠肽段来确定的。PSPI - 21的两种蛋白质都由两条链组成，分别命名为A链和B链，它们通过Cys(146)和Cys(157)之间的二硫键相连。另一个二硫键位于A链中Cys(48)和Cys(97)之间。两种形式的大A链的氨基酸序列各由150个氨基酸残基组成，在第52位的单个残基上有所不同。小B链在PSPI - 21 - 6.3和PSPI - 21 - 5.2中分别含有37和36个残基，有9个不同的残基。这两种抑制剂的完整氨基酸序列与植物中其他Kunitz型蛋白酶抑制剂具有高度同源性。
