Amino-acid activation by individual enzymes.

Abstract

I should like to comment on one aspect of Dr Gutfreund’s interesting paper. As he mentioned, we have found evidence that amino acids, after becoming enzymically activated by ATP through the formation of an enzyme-bound amino acyladenylate compound, are transferred to a low molecular weight RNA which, by accident or design, resides in the same crude activating enzyme fraction. It is gratifying that Dr Gutfreund has found a distribution pattern of amino acids on this RNA which roughly agrees with the pattern in the major protein products of mammary tissue. He points out, however, that there is no such correlation when one looks at the pattern of amino-acid activation. Indeed, because of this anomaly, some workers have devised theories of activation involving transacylation steps to account for activation of those amino acids for which an enzyme has not been found. Dr Gutfreund implies that there is much confusion and mystery here, and even suggests that the specificity of activation might be accounted for by soluble RNA , rather than by individual enzymes.