THE SITE FOR GTP HYDROLYSIS ON THE ARCHAEAL ELONGATION-FACTOR-2 IS UNMASKED BY ALIPHATIC-ALCOHOLS

An appropriate mixture of ethylene glycol and BaCl2 enhanced the other wise very low intrinsic GTPase activity of the elongation factor 2 iso lated from the archaeon Sulfolobus solfataricus (SsEF-2). The enzymati c activity became up to 300-fold higher than that of the SsEF-2 GTPase measured in the absence of any stimulator, but remained 20-fold lower than that stimulated by ribosome. The stimulatory effect of ethylene glycol/Ba2+ was attributed to the increased affinity for GTP, probably related to a conformational change occurring in a hydrophobic region near the catalytic site.