Homocoenzyme B<sub>12</sub>and Bishomocoenzyme B<sub>12</sub>: Covalent Structural Mimics for Homolyzed, Enzyme-Bound Coenzyme B<sub>12</sub>
作者:Sigrid Gschösser、Renate B. Hannak、Robert Konrat、Karl Gruber、Christian Mikl、Christoph Kratky、Bernhard Kräutler
DOI:10.1002/chem.200400701
日期:2005.1
solution were carried out and a high-resolution crystal structure of 2 was obtained. The two homologues of coenzyme B(12) (2 and 3) are suggested to function as covalent structural mimics of the hypothetical enzyme-bound "activated" (that is, "stretched" or even homolytically cleaved) states of the B(12) cofactor. From crude molecular models, the crucial distances from the corrin-bound cobalt center to the
“同型辅酶B(12)”(2,Coβ-(5'-脱氧-5'-腺苷甲基)-芯(III)丙氨酸)和“双同型辅酶B(12)”的高效电化学合成(3,本文报道了Coβ-[2-(5'-脱氧-5'-腺苷)-乙基] -Cob(III)丙氨酸。这些合成分别提供了2%和3%的结晶样品,产率分别为94%和77%。此外,对溶液中2和3的结构进行了深入研究,并获得了2的高分辨率晶体结构。建议辅酶B(12)的两个同源物(2和3)作为B(12)的假设酶结合“激活”(即“伸展”或什至被同质切割)状态的共价结构模拟物起作用。辅助因子。根据粗分子模型,据估计,在2和3中,从柯林结合的钴中心到(均)腺苷部分C5'原子的临界距离分别约为3.0和4.4A。这些值与谷氨酸突变酶的晶体结构中辅酶B(12)的两种“激活”形式中发现的值大致相同。实际上,在2的晶体结构中,观察到钴中心与高腺苷部分的C5'原子的距离为2.99A,并且发现后者以不