REFOLDING OF DENATURED LACTATE-DEHYDROGENASE BY ESCHERICHIA-COLI RIBOSOMES

Escherichia coli ribosomes were used to refold denatured lactate dehyd rogenase from porcine muscle. This activity of ribosomes, unlike most of the chaperons, did not require the presence of ATP. The molar conce ntration of ribosomes required for this refolding was comparable with that of the enzyme. Restoration of the enzyme activity was demonstrate d using assays for both the forward and backward reactions. Binding of the denatured enzyme to ribosomes and its refolding were fairly rapid processes as revealed by the time course of the reaction and inhibiti on of folding when the denatured enzyme was allowed to refold spontane ously for short times before the addition of ribosomes. This protein-f olding activity was detected in 70 S ribosomes as well as its RNA, in 50 S particles and in 23 S rRNA. However, 30 S particles failed to ref old the enzyme.