Hahn K W, Klis W A, Stewart J M
Department of Biochemistry, University of Colorado Medical School, Denver 80262.
Science. 1990 Jun 22;248(4962):1544-7. doi: 10.1126/science.2360048.
A peptide having enzyme-like catalytic activity has been designed and synthesized. Computer modeling was used to design a bundle of four short parallel amphipathic helical peptides bearing the serine protease catalytic site residues serine, histidine, and aspartic acid at the amino end of the bundle in the same spatial arrangement as in chymotrypsin (ChTr). The necessary "oxyanion hole" and substrate binding pocket for acetyltyrosine ethyl ester, a classical ChTr substrate, were included in the design. The four chains were linked covalently at their carboxyl ends. The peptide has affinity for ChTr ester substrates similar to that of ChTr and hydrolyzes them at rates approximately 0.01 that of ChTr; total turnovers greater than 100 have been observed. The peptide is inhibited by ChTr specific inhibitors and is inactive toward benzoyl arginine ethyl ester, a trypsin substrate. The peptide is inactivated by heating above 60 degrees C, but recovers full catalytic activity upon cooling and lyophilization from acetic acid.
一种具有类酶催化活性的肽已被设计并合成出来。利用计算机建模设计了一束由四条短的平行两亲性螺旋肽组成的肽束，在肽束的氨基末端带有丝氨酸蛋白酶催化位点残基丝氨酸、组氨酸和天冬氨酸，其空间排列与胰凝乳蛋白酶（ChTr）中的相同。设计中包含了经典ChTr底物乙酰酪氨酸乙酯所需的“氧阴离子洞”和底物结合口袋。四条链在其羧基末端共价连接。该肽对ChTr酯底物的亲和力与ChTr相似，并以约为ChTr水解速率0.01的速度水解它们；已观察到总周转数大于100。该肽被ChTr特异性抑制剂抑制，对胰蛋白酶底物苯甲酰精氨酸乙酯无活性。该肽在60摄氏度以上加热会失活，但冷却并从乙酸中冻干后可恢复全部催化活性。
