title: N- and C-terminal amino acids of purified alpha-actinin.
abstract: Highly purified bovine cardiac alpha-actinin is obtained by successive chromatography on DEAE-cellulose and hydroxyapatite of a crude fraction obtained by salting out low ionic strength extracts of bovine cardiac muscle between 0 and 30% ammonium sulfate saturation. Hydroxyapatite chromatography removes a 43 000-dalton polypeptide chain that is difficult to remove by successive DEAE-cellulose columns. Removal of all 43 000-dalton material by hydroxyapatite chromatography is accompanied by disappearance of a very small 9 to 10 S boundary in analytical ultracentrifuge diagrams of DEAE-cellulose-purified 6.2S alpha-actinin. Approximately 95% of the protein in DEAE-cellulose and hydroxyapatite-purified alpha-actinin is the 100 000-dalton alpha-actinin polypeptide as estimated by SDS-polyacrylamide gel electrophoresis. Purified bovine cardiac, porcine skeletal, chicken gizzard, and chicken breast alpha-actinins all contain leucine as the C-terminal amino acid of both polypeptide chains in the alpha-actinin molecule. Bovine cardiac and porcine skeletal alpha-actinins contain arginine as the amino acid penultimate to C-terminal leucine. None of the four different alpha-actinins studied had a N-terminal amino group available for reaction with dansyl chloride, but all four alpha-actinins contained 1.6 to 1.8 acetate residues per molecule (200 000 daltons) of alpha-actinin. It seems likely that the N-terminal amino groups of both polypeptide chains in these four alpha-actinins are acetylated. A peptide having the composition N-Ac-Asp2-Glu4 was isolated from a proteolytic digest of bovine cardiac alpha-actinin. alpha-Actinin seems to be a conserved protein molecule found in many different motile systems.
mesh_terms: D000185:Actinin / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism; D002417:Cattle; D002645:Chickens; D002848:Chromatography, DEAE-Cellulose; D005895:Gizzard, Avian; D007700:Kinetics; D009124:Muscle Proteins / Q000302:isolation & purification; D009132:Muscles; D009206:Myocardium; D009928:Organ Specificity; D013045:Species Specificity; D013552:Swine
chemical_list: D000596:Amino Acids; D009124:Muscle Proteins; D000185:Actinin; D002268:Carboxypeptidases