Chemical studies on the cysteine and terminal peptides in tryptic digests of actin.
1. On exhaustive digestion of carboxymethylated actin in 6m-urea solutions with carboxypeptidase A, 1 mole of phenylalanine was liberated/43000g. of protein. At a lower urea concentration and in the absence of urea, carboxymethyl-cysteine (CMCys) was also liberated. 2. Three cysteine-containing peptides were identified by the study of peptide ;maps' of tryptic digests of actin treated with thiol reagents. 3. The three peptides, each containing one residue of CMCys, were isolated from tryptic digests of carboxymethylated actin by ion-exchange chromatography. 4. One of these peptides was possibly the N-terminal peptide and contained about 17-18 residues; another was CMCys-Asp-Ile-Asp-Ile-Arg; the other, CMCys-Phe, was the C-terminal tryptic peptide. 5. The chemical evidence suggests that the actin molecule consists of a single polypeptide chain of molecular weight about 44000.
D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D003545:Cysteine / Q000032:analysis*; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis*; D010455:Peptides / Q000032:analysis*; D010649:Phenylalanine; D014357:Trypsin; D014508:Urea / Q000032:analysis
D009124:Muscle Proteins; D010455:Peptides; D010649:Phenylalanine; D014508:Urea; D014357:Trypsin; D003545:Cysteine