[Show abstract][Hide abstract] ABSTRACT: Low molecular weight components (g1, g2, and g3) were isolated from rabbit skeletal muscle myosin and their amino acid compositions were analyzed. One mole tryptophan was found in g1 and in g2, but none in g3. One mole of acetic acid was found per mole of each g-chain and it was concluded that the N-terminal groups of all three g-chains are acetylated. The minimum molecular weight of the g-chains were estimated from their amino acid compositions. It was estimated by SDS-disc electrophoresis that 1 mole of myosin contained 0.90, 1.7, and 0.63 moles of g1, g2, and g3, respectively. Similar values were obtained with psoas muscle myosin, but in heavy meromyosin prepared from skeletal muscle myosin the content of g2 was much lower, and that of g3 was much higher.
No preview · Article · Mar 1975 · Journal of Biochemistry
[Show abstract][Hide abstract] ABSTRACT: An enzymatically active subfragment of myosin was isolated by Nagarse digestion of myosin. It was shown to be homogeneous by the determinations of ultracentrifuge, gel filtration of Sephadex G 200 and polyacrylamide gel electrophoresis. Physical parameters of the subfragment were similar to those of other subfragments prepared by tryptic, chymotryptic, or papain digestion. The subfragment binds strongly to F actin at the molar ratio of 1, but the activity of actin activated Mg ATPase was very low and the acceleration of actin polymerization was hardly observed. The number of moles of N terminal amino acids of the subfragment was about 2.62 moles per mole, which suggests an intramolecular peptide bond cleavage. It was also indicated by intrinsic viscosity and gel filtration chromatography obtained in 5 M guanidine HCl. In 5M guanidine HCl, the subfragment separated into two components and the molecular weight of one component of 32.2% in weight was 4.3X10 4 and that of another component of 64.8% in weight was about 1.8X10 4. The properties were compared with those of the subfragments prepared by using chymotrypsin, trypsin, and trypsin Nagarse as proteolytic enzymes. Similar results were obtained with the subfragment prepared by tryptic digestion of heavy meromyosin. The extent of proteolysis was less in the one digested by chymotrypsin and more in trypsin Nagarse than the one digested with Nagarse or trypsin.
No preview · Article · Apr 1973 · Journal of Biochemistry
[Show abstract][Hide abstract] ABSTRACT: 1. A correlation between elution volume of a solute in gel filtration and molecular weight of the solute was investigated in 5M guanidine hydrochloride by using proteins of known molecular weight. Sepharose 4B, Sepharose 6B, Sephadex G-200, and Sephadex G-100 were used in the medium of 5 m guanidine hydrochloride, lmM EDTA, and 20 mM Tris-HCl buffer (pH7.6) with or without β-mercaptoethanol. A plot of log molecular weight versus elution volume yields a linear relation with Sepharose 6B, Sephadex G-200, and Sephadex G-100, from which molecular weights can be estimated with an uncentainty of approximately 11-14 percent.2. Subunit structures of myosin, heavymeromyosin, lightmeromyosin-fraction 1, and actin were examined by the method using gel filtration described above. Molecular weights of the constitutive polypeptide chains were estimated and difference between heavymeromyosins prepared by tryptic and chymotryptic digestions was observed.
No preview · Article · Nov 1972 · Journal of Biochemistry