Frey P A, Whitt S A, Tobin J B
Institute for Enzyme Research, Graduate School, University of Wisconsin at Madison 53705.
Science. 1994 Jun 24;264(5167):1927-30. doi: 10.1126/science.7661899.
Spectroscopic properties of chymotrypsin and model compounds indicate that a low-barrier hydrogen bond participates in the mechanism of serine protease action. A low-barrier hydrogen bond between N delta 1 of His57 and the beta-carboxyl group of Asp102 in chymotrypsin can facilitate the formation of the tetrahedral adduct, and the nuclear magnetic resonance properties of this proton indicate that it is a low-barrier hydrogen bond. These conclusions are supported by the chemical shift of this proton, the deuterium isotope effect on the chemical shift, and the properties of hydrogen-bonded model compounds in organic solvents, including the hydrogen bond in cis-urocanic acid, in which the imidazole ring is internally hydrogen-bonded to the carboxyl group.
胰凝乳蛋白酶及模型化合物的光谱性质表明，一个低势垒氢键参与了丝氨酸蛋白酶的作用机制。在胰凝乳蛋白酶中，His57的Nδ1与Asp102的β-羧基之间的低势垒氢键能够促进四面体加合物的形成，并且该质子的核磁共振性质表明它是一个低势垒氢键。这些结论得到了该质子的化学位移、化学位移的氘同位素效应以及有机溶剂中氢键模型化合物性质的支持，包括顺式尿刊酸中的氢键，其中咪唑环与羧基形成分子内氢键。
