Nilsson L, Nygård O
Biochim Biophys Acta. 1984 May 15;782(1):49-54. doi: 10.1016/0167-4781(84)90105-2.
During the translocation of the nascent peptide chain from the ribosomal aminoacyl-site to the peptidyl-site, GTP is hydrolyzed by a mechanism dependent on both ribosomes and the elongation factor EF-2. For insight into the mechanism of GTP hydrolysis, we studied the ability of the GTP analogue 5'-p- fluorosulfonylbenzoylguanosine ( FSO2BzGuo ) to act as an affinity label of the guanine-specific site. Pre-incubation of EF-2 with FSO2BzGuo at increasing concentrations progressively inactivated the EF-2 and ribosome-dependent GTPase activity. Up to 0.5 mM FSO2BzGuo , the inactivation of the GTPase activity was stoichiometrically correlated with the covalent binding of [3H] FSO2BzGuo . Thus, one molecule of covalently bound FSO2BzGuo completely inactivated the GTPase activity of EF-2. Ribosomes or 60-S ribosomal subunits pre-incubated with FSO2BzGuo were not inactivated, consistent with the idea that the GTP hydrolysis involved in the ribosomal translocation takes place on EF-2.
在新生肽链从核糖体氨酰位点转移至肽酰位点的过程中，GTP通过一种依赖于核糖体和延伸因子EF-2的机制被水解。为深入了解GTP水解的机制，我们研究了GTP类似物5'-对氟磺酰苯甲酰鸟苷（FSO2BzGuo）作为鸟嘌呤特异性位点亲和标记物的能力。用浓度递增的FSO2BzGuo对EF-2进行预孵育会逐渐使EF-2和核糖体依赖性GTP酶活性失活。在高达0.5 mM的FSO2BzGuo浓度下，GTP酶活性的失活与[3H]FSO2BzGuo的共价结合呈化学计量相关。因此，一分子共价结合的FSO2BzGuo会完全使EF-2的GTP酶活性失活。用FSO2BzGuo预孵育的核糖体或60-S核糖体亚基并未失活，这与核糖体转位过程中涉及的GTP水解发生在EF-2上的观点一致。
