Polyclonal antibodies raised against a synthetic pcptide consisting of the last 19 amino acids at the end of the coiled-coil region of the heavy chains inhibited the actin-activated Mg2+-ATPase activity of myosin II and its ability to form filaments. Antibodies against a synthetic peptide corresponding to the 21 adjacent amino acids at the beginning of the nonhelical tailpiece, which include the three regulatory phosphorylatable serines, had no effect on either activity.
In order to examine the effect of a defined enantiomeric sequence on protein structure, the all‐d model ribonuclease S‐peptide, H‐Ala‐Glu‐Ala4‐Lys‐Phe‐Ala‐Arg‐Ala‐His‐Met‐Ala2‐OH, has been synthesized by the solid phase method. The all‐L peptide has been synthesized previously and shown to possess 36% of ribonuclease S activity when added to ribonuclease S‐protein (Komoriya, A. & Chaiken, I.M. (1982) J. Biol. Chem. 257, 2599–2604). The synthetic d‐peptide was purified by gel filtration and semipreparative reverse phase HPLC. Amino acid composition of the synthetic peptide was in agreement with theory and gas chromatographic analysis showed that no significant racemization had occurred during synthesis. Circular dichroism (CD) studies of the d‐peptide showed a peak of positive ellipticity in the 220–230 nm region, whereas a negative ellipticity peak for the l‐peptide was observed. The effects of temperature and trifluoroethanol on the far‐ultraviolet CD spectra of d‐ and l‐peptides were similar but of opposite sign, confirming the expectation that the d‐peptide has the propensity to form an α‐helical structure which is enantiomeric with respect to that formed by the l‐peptide. In the presence of S‐protein, the l‐peptide showed hydrolytic activity against the substrate cytidine‐2′:3′‐monophosphate, whereas the d‐peptide was inactive. Addition of the d‐peptide to mixtures of l‐peptide and S‐protein did not lead to inhibition of enzymatic activity. These results indicate lack of binding of d‐peptide to S‐protein to produce either an active or inactive species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.