JBC, Vol. 252, Issue 10, 3252-3254, May, 1977

Complementation of peptides of barnase, extracellular ribonuclease of Bacillus amyloliquefaciens

R. W. Hartley

Recovery of ribonuclease activity by complementation of peptides of barnase is reported. Activity is restored to barnase-(1-102), which lacks eight amino acids from its COOH terminus, by combination with peptides-(88-110), -(95-110), or -(99-108), and also with succinylated peptide-(88-110). The dissociation constants are about 8 X 10(-6) M for the first two combinations and little, if any, greater for the other two. Based on barnase-(1-102) concentration, up to 80% of native activity is obtained with peptide-(88-110) but only 5 to 20% with the others. The octapeptide-(103-110), equivalent to the residues missing from barnase-(1-102), does not complement barnase-(1-102), suggesting that an intact sequence about His-102 and Tyr-103 is required for activity. Barstar, the natural inhibitor of barnase, completely inhibits all activity of the complementing peptides.
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