Sharma H K, Rothstein M
Proc Natl Acad Sci U S A. 1980 Oct;77(10):5865-8. doi: 10.1073/pnas.77.10.5865.
Young- and old-type enolases (2-phospho-D-glycerate hydrolyase, EC 4.2.1.11) from the free-living nematode Turbatrix aceti can be unfolded in 1.25 M guanidine hydrochloride and subsequently refolded with essentially a quantitative recovery. After refolding, both enolases form an identical or near-identical third type of the enzyme as determined by spectral criteria, sensitivity to heat, immunotitration, and rate of inactivation by bacterial protease. By the same criteria, the refolded enolase is closer in conformation to the native old form of the enzyme than to the young form. The results prove that young and old enolases are conformational isomers and that an in vivo transformation from young to old enzyme takes place by conformational changes without covalent modification. The process may be related to the previously demonstrated slowing of enolase turnover in T. aceti. Errors in sequence cannot be involved in the age-related alteration of the enzyme.
来自自由生活线虫醋酸醋线虫的年轻型和老年型烯醇化酶（2-磷酸-D-甘油酸水解酶，EC 4.2.1.11）可在1.25 M盐酸胍中展开，随后复性，复性回收率基本定量。复性后，通过光谱标准、热敏感性、免疫滴定和细菌蛋白酶失活速率测定，两种烯醇化酶均形成相同或近乎相同的第三种酶类型。通过相同标准，复性后的烯醇化酶在构象上更接近该酶的天然老年形式，而非年轻形式。结果证明，年轻型和老年型烯醇化酶是构象异构体，并且在体内从年轻型酶到老年型酶的转变是通过构象变化而非共价修饰发生的。该过程可能与先前证明的醋酸醋线虫中烯醇化酶周转减慢有关。序列错误不可能参与该酶与年龄相关的改变。
