Brauer Arnd B E, Leatherbarrow Robin J
Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Biochem Biophys Res Commun. 2003 Aug 22;308(2):300-5. doi: 10.1016/s0006-291x(03)01365-2.
The isolated reactive site beta-hairpin loop of Bowman-Birk-type proteinase inhibitors has become a widely studied proteinomimetic because it retains the three-dimensional structure and much of the inhibitory potency of the corresponding region of the complete protein. Here we analyse the role of the P1' Ser residue which is highly conserved and intramolecularly hydrogen bonded in the complete proteins. A combined kinetic and structural analysis of variant proteinomimetic peptides demonstrates that the hydrogen-bond potential of the side-chain oxygen atom of the P1' Ser is not essential for the integrity of the reactive site loop and that it provides only a small contribution to the trypsin affinity and no apparent contribution to the stability against tryptic turnover. We conclude that the potential of the P1' side chain to engineer improved inhibition and selectivity for serine proteinases is best explored further in concert with the side chains of the P2 and P5' residues which may interact or compete for the same space.
鲍曼-伯克型蛋白酶抑制剂中分离出的反应位点β-发夹环，已成为一种被广泛研究的蛋白质模拟物，因为它保留了完整蛋白质相应区域的三维结构和大部分抑制活性。在此，我们分析了P1'丝氨酸残基的作用，该残基在完整蛋白质中高度保守且形成分子内氢键。对变异蛋白质模拟肽的动力学和结构联合分析表明，P1'丝氨酸侧链氧原子的氢键潜力对于反应位点环的完整性并非必不可少，并且它对胰蛋白酶亲和力的贡献很小，对抵抗胰蛋白酶周转的稳定性没有明显贡献。我们得出结论，与可能相互作用或竞争同一空间的P2和P5'残基的侧链协同作用，能更好地进一步探索P1'侧链设计改善对丝氨酸蛋白酶抑制作用和选择性的潜力。
