Ringe D, Seaton B A, Gelb M H, Abeles R H
Biochemistry. 1985 Jan 1;24(1):64-8. doi: 10.1021/bi00322a011.
The inactivation of chymotrypsin by 5-benzyl-6-chloro-2-pyrone has been studied. Chloride analysis of the inactivated enzyme suggests that chlorine is no longer present in the complex. 13C NMR spectroscopy of chymotrypsin inactivated with 5-benzyl-6-chloro-2-pyrone-2,6-13 C2 shows the presence of two new resonances from the protein-bound inactivator. The chemical shift values of these resonances are consistent with an intact pyrone ring on the enzyme as well as the replacement of the C-6 chlorine by a different heteroatom. X-ray diffraction analysis at 1.5-A resolution of the inactivator-enzyme complex demonstrates that the gamma-oxygen of the active site serine residue (serine 195) is covalently attached to C-6 of the inactivator and that the pyrone ring is intact. The 5-benzyl group of the inactivator is bound to the enzyme in the hydrophobic specificity pocket. The conformational changes that occur in the protein as a result of complexation with the inactivator are discussed.
研究了5-苄基-6-氯-2-吡喃酮对胰凝乳蛋白酶的失活作用。对失活酶进行的氯分析表明，复合物中不再存在氯。用5-苄基-6-氯-2-吡喃酮-2,6-¹³C₂使胰凝乳蛋白酶失活后进行的¹³C NMR光谱分析显示，存在来自与蛋白质结合的失活剂的两个新共振峰。这些共振峰的化学位移值与酶上完整的吡喃酮环以及C-6位的氯被不同杂原子取代的情况一致。对失活剂-酶复合物进行1.5埃分辨率的X射线衍射分析表明，活性位点丝氨酸残基（丝氨酸195）的γ-氧与失活剂的C-6位共价连接，且吡喃酮环完整。失活剂的5-苄基基团结合在酶的疏水特异性口袋中。讨论了与失活剂复合后蛋白质中发生的构象变化。
