Effect of Neutral Pyridine Leaving Groups on the Mechanisms of Influenza Type A Viral Sialidase-Catalyzed and Spontaneous Hydrolysis Reactions of α-<scp>d</scp>-<i>N</i>-Acetylneuraminides
作者:Doug T. H. Chou、Jacqueline N. Watson、Andrew A. Scholte、Thor J. Borgford、Andrew J. Bennet
DOI:10.1021/ja001641x
日期:2000.9.1
parameters calculated from the hydrolysis of pyridinium α-d-N-acetylneuraminide (ΔH⧧ = 112 ± 2 kJ mol-1 and ΔS⧧ = 28 ± 4 J mol-1 K-1), strongly suggest that the anomeric carboxylate does not assist in the departure of neutral pyridine leaving groups. Enzymatic hydrolysis was studied using an influenza viral α-sialidase (A/Tokyo/3/67) which was recombinantly expressed using ...
合成了由 α-dN-乙酰神经氨酸的五种吡啶盐组成的试剂组,然后用于探测神经氨酸水解的酶促(α-唾液酸酶)和非酶促机制。吡啶盐的自发水解通过两个独立的途径进行,其中无辅助的 CN 键断裂是速率决定步骤。阳离子物质(即质子化的异头羧酸盐)显示出在 0.4-0.7 范围内的表观 pKa 值。然而,阳离子和两性离子物质的自发水解具有相似的βlg 值,分别为-1.22 ± 0.16 和-1.22 ± 0.07。结果,加上从吡啶鎓α-dN-乙酰神经氨酸的水解计算的活化参数(ΔH⧧ = 112 ± 2 kJ mol-1 和 ΔS⧧ = 28 ± 4 J mol-1 K-1),强烈建议异头羧酸盐不帮助中性吡啶离去基团的离开。使用流感病毒 α-唾液酸酶 (A/Tokyo/3/67) 研究酶促水解,该酶使用...