Stoddard B L, Bruhnke J, Porter N, Ringe D, Petsko G A
Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.
Biochemistry. 1990 May 22;29(20):4871-9. doi: 10.1021/bi00472a017.
The serine protease gamma-chymotrypsin was covalently inhibited with two different photoreversible cinnamate compounds, and the structures of the resulting complexes were determined to 1.9-A resolution. The inhibitors show different kinetics of binding, inhibition, and nonphotochemical deacylation relative to each other in solution activity assays. The crystal structures of the enzyme-cinnamate complexes show that both compounds acylate serine 195 and that the two molecules are bound in similar nonproductive conformations which have drastic effects on their ability to turn over. Substitution of a diethylamino group on the para position of the cinnamate ring causes a 1000-fold increase in the thermal stability of the inhibitor toward hydrolysis and deacylation.
丝氨酸蛋白酶γ-胰凝乳蛋白酶与两种不同的光可逆肉桂酸酯化合物发生共价抑制作用，所得复合物的结构被测定至1.9埃分辨率。在溶液活性测定中，这些抑制剂相对于彼此显示出不同的结合、抑制和非光化学脱酰动力学。酶-肉桂酸酯复合物的晶体结构表明，两种化合物均使丝氨酸195酰化，且两个分子以相似的无活性构象结合，这对它们的周转能力有显著影响。在肉桂酸环的对位上取代二乙氨基会使抑制剂对水解和脱酰的热稳定性提高1000倍。
