PubMed Health⌕ Search

Biomedical subjects

S V Perry

Publications and source records attributed to S V Perry.

At least 109 records · Page 6Linked to original sources
PubMed1975

Phosphorylation of the light-chain components of myosin from cardiac and red skeletal muscles.

1. The light-chain components of myosin from cardiac muscle (19000 and 27000 daltons) and of rabbit soleus and crureus muscles (19000, 27000 and 29000 daltons) were characterized. 2. The 19000-dalton components in carciac- and red-skeletal-muscle myosins were spontaneously modified to a component of slightly higher net negative charge. 3. The 19000-dalton component in cardiac and red skeletal muscles and their modified forms were phosphorylated by myosin light-chain kinase. 4. Evidence was obtained for the presence of myosin light-chain kinase in cardiac and red skeletal muscles. 5. Myosin light-chain kinase catalysed the phosphorylation of the whole light-chain fraction from white and red skeletal muscle at similar rates. The light-chain fraction of cardiac-muscle myosin was phosphorylated at a significantly lower rate. 6. The light-chain components of cardiac-muscle myosin and their phosphorylated froms were separated by ion-exchange chromatography and their amino acid compositions determined.

Amino Acids↗
PubMed1974

The interaction of the calcium-binding protein (troponin C) with bivalent cations and the inhibitory protein (troponin I).

1. The molecular weight of the calcium-binding protein of rabbit white skeletal muscle was estimated to be 18500 by sedimentation equilibrium and electrophoresis in sodium dodecyl sulphate. 2. Addition of 2 Ca(2+) ions per molecule produced reversible changes in the u.v.-absorption spectrum that are interpreted as arising from conformational changes in the structure of the protein. 3. Cd(2+) was almost as effective as Ca(2+) in producing the spectral changes. Other bivalent metal ions, particularly Mg(2+), were less effective. 4. Binding of Ca(2+) by the calcium-binding protein produced an increase in mobility to the anode on electrophoresis in 6m-urea at pH8.6. The Ca(2+)-saturated form of the protein was more retarded on gel filtration than the Ca(2+)-free form. 5. In the presence of Ca(2+) the calcium-binding protein formed an equimolar complex with the inhibitory protein. This complex was stable in 8m-urea and in the pH range 7.0-8.6. 6. An isotope-dilution method for the measurement of the content of calcium-binding protein in whole muscle is described. In rabbit psoas muscle the ratio of actin monomers to molecules of calcium-binding protein was approx. 7:1. Similar values were obtained for red skeletal and cardiac muscle. 7. Evidence is presented indicating that in the rabbit the inhibitory protein of the troponin complex of red skeletal and cardiac muscles is different from the inhibitory protein of white skeletal muscle.

Actins↗
PubMed1974

Chemical and immunochemical characteristics of tropomyosins from striated and smooth muscle.

1. On electrophoresis in dissociating conditions the tropomyosins isolated from skeletal muscles of mammalian, avian and amphibian species migrated as two components. These were comparable with the alpha and beta subunits of tropomyosin present in rabbit skeletal muscle. 2. The alpha and beta components of all skeletal-muscle tropomyosins contained 1 and 2 residues of cysteine per 34000g respectively. 3. The ratio of the amounts of alpha and beta subunit present in skeletal muscle tropomyosins was characteristic for the muscle type. Muscle consisting of slow red fibres contained a greater proportion of beta-tropomyosin than muscles consisting predominantly of white fast fibres. 4. Mammalian and avian cardiac muscle tropomyosins consisted of alpha-tropomyosin only. 5. Mammalian and avian smooth-muscle tropomyosins differed both chemically and immunologically from striated-muscle tropomyosins. 6. Antibody raised against rabbit skeletal alpha-tropomyosin was species non-specific, reacting with all other striated muscle alpha-tropomyosin subunits tested. 7. Antibody raised against rabbit skeletal beta-tropomyosin subunit was species-specific.

Amphibians↗
PubMed1974

Phosphorylation of troponin and the effects of interactions between the components of the complex.

1. The troponin complex from skeletal muscle contains approximately 1 mol of phosphate/80000g of complex, covalently bound to the troponin T component. 2. On prolonged incubation of the troponin complex or troponin T with phosphorylase kinase the phosphate content of troponin T was increased to approx. 3mol/mol. 3. On prolonged incubation of troponin I with phosphorylase kinase up to 1.6mol of phosphate/mol were incorporated. 4. Phosphorylation of troponin I was greatly inhibited by troponin C owing to the strong interaction between these proteins. Thus in the troponin complex troponin T was the main substrate for phosphorylase kinase. The phosphorylation of isolated troponin T was also inhibited by troponin C. 5. Troponin I was phosphorylated when the troponin complex was incubated with a bovine cardiac 3':5'-cyclic AMP-dependent protein kinase. Troponin T either in its isolated form or in the troponin complex was not phosphorylated by bovine protein kinase to any significant extent under the conditions used. 6. If the troponin complex was dephosphorylated to 0.2mol/mol, or phosphorylated up to 2.5mol/mol there was no significant effect on the ability of normal concentrations to confer Ca(2+) sensitivity on the adenosine triphosphatase of densensitized actomyosin.

Actomyosin↗
PubMed1973

Studies on the heterogeneity of subfragment-1 preparations. Isolation of a new proteolytic fragment of the heavy chain of myosin.

1. The physical, chemical and enzymic properties of subfragment 1 prepared from myosin of rabbit skeletal muscle by using two different concentrations of insoluble papain were compared. 2. Subfragment 1 prepared by using a myosin/papain ratio of 2000: 1 (by wt.) migrated on electrophoresis in non-dissociating conditions as a single enzymically active band. When prepared with a myosin/papain ratio of 200: 1 the preparation consisted of two enzymically active components of slightly different electrophoretic mobility. 3. The two types of preparation were obtained in similar yield and possessed similar specific adenosine triphosphatase activities when determined in the presence of Ca(2+). 4. Gel electrophoresis in the presence of 8m-urea showed that both preparations contained three light components. The component of molecular weight 15500 was apparently identical with one of the light-chain components of myosin (Ml(1)). The other two light-chain components of subfragment 1 were not identical with any of the light-chain components of myosin. 5. The heavy-chain fraction of subfragment 1 prepared by using low concentrations of papain dissociated into components with molecular weights of 87000, 69000 and 26000 on electrophoresis in sodium dodecyl sulphate. The heavy-chain fraction of subfragment 1 prepared by using higher concentrations of papain contained components with molecular weights of 69000 and 53000 and relatively increased amounts of the component of molecular weight 26000. 6. The isolated 26000 dalton component had an amino acid composition similar to that of the heavy-chain fraction of subfragment 1 and contained 3-methylhistidine and mono-and tri-N(epsilon)-methyl-lysine. It was homogeneous on electrophoresis in the presence of sodium dodecyl sulphate but gave two bands on electrophoresis in 8m-urea.

Adenosine Triphosphatases↗
PubMed1973

Phosphorylation of the "37000 component" of the troponin complex (troponin-t).

Most of the phosphorus present in the troponin complex, which on average contains 1 mol of P/80000g, is associated with the ;37000 component' (0.6mol of P/mol). The inhibitory protein and particularly the ;37000 component', but not the calcium-binding protein, were phosphorylated when incubated with phosphorylase b kinase and [gamma-(32)P]ATP.

Animals↗
PubMed1973

The subunits and biological activity of polymorphic forms of tropomyosin.

1. Free thiol groups were shown to be essential for tropomyosin to effect maximum inhibition of the Ca(2+)-stimulated ATPase (adenosine triphosphatase) of desensitized actomyosin but not for its activity in the regulatory-protein system. 2. The activity of tropomyosin on the Mg(2+)-stimulated ATPase in the regulatory-protein system was more susceptible to enzymic digestion and thermal denaturation than its effect on the Ca(2+)-stimulated ATPase of actomyosin. 3. Rabbit skeletal tropomyosin migrated as two distinct electrophoretic components in the presence of sodium dodecyl sulphate and urea and as four components on isoelectric focusing in urea. 4. The two main subunits present in rabbit skeletal tropomyosin, which have been named the alpha- and beta-chains, were separated by chromatography on CM-cellulose in urea at pH4.0. They were shown to be virtually identical in amino acid composition, except for their cysteine contents. The alpha(2) and beta(2) forms of tropomyosin possessed all the biological activities characteristic of normal tropomyosin preparations. 5. In skeletal muscle the alpha and beta components of tropomyosin were present in the proportion of 4:1. Somewhat lower ratios were obtained in skeletal muscle of sheep, pig and cow. 6. Tropomyosin isolated from cardiac muscle and Pecten maximus adductor muscle migrated as one band only. These tropomyosins possessed similar biological activities to those isolated from skeletal muscle.

Actomyosin↗
PubMed1972

The regulatory proteins of the myofibril. Characterization and biological activity of the calcium-sensitizing factor (troponin A).

1. Electrophoretically homogeneous calcium-sensitizing factor was prepared from the troponin complex by chromatography successively on sulphoethyl-Sephadex and on diethyl-(2-hydroxypropyl)aminoethyl-Sephadex in 6m-urea. It is a protein containing 53% of polar amino acids, of which a net excess consists of acidic residues. 2. On gel filtration the calcium-sensitizing factor was shown to be the only myofibrillar protein that bound (45)Ca(2+) tightly in the presence of 2-6m-urea. 3. Calcium-sensitizing factor effectively neutralized the effect of the inhibitory factor on the ATPase activities of actomyosin systems. Tropomyosin was essential for the regulation, by changes in the Ca(2+) concentration, of the neutralizing effect of calcium-sensitizing factor on the inhibitory factor. 4. Prolonged exposure to chelators of Ca(2+) produced an irreversibly modified form of calcium-sensitizing factor of higher electrophoretic mobility at pH8.6. The modified form neutralized the inhibitory factor action but this property could no longer be controlled by the Ca(2+) concentration in the presence of tropomysin. 5. The calcium-sensitizing factor and tropomyosin could be replaced by their carboxymethylated derivatives in the relaxing-protein system.

Actomyosin↗
PubMed1972

The regulatory proteins of the myofibril. Separation and biological activity of the components of inhibitory-factor preparations.

1. Inhibitory-factor preparations isolated from myofibrils were shown to consist principally of proteins with molecular weights of 37000 and 23000. Under certain preparative procedures an additional component of molecular weight 14000 was present. 2. The 23000-dalton protein, the inhibitory factor, was the major active component. Its activity was enhanced by tropomyosin. 3. The 14000-dalton component also possessed inhibitory activity, although less than that of the 23000-dalton component when compared on a molar basis. Its activity was not always enhanced by tropomyosin. The 14000-dalton component could not be detected in whole fresh myofibrils and the limited evidence available is compatible with its formation during the preparation of the troponin complex. 4. The 37000-dalton component could not replace the inhibitory factor, calcium-sensitizing factor or tropomyosin as components of the relaxing-protein system. 5. All three components had distinctive amino acid compositions, particularly in their cysteine content.

Actomyosin↗