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S V Perry

Publications and source records attributed to S V Perry.

At least 73 records · Page 4Linked to original sources
PubMed1979

Troponin C-like proteins (calmodulins) from mammalian smooth muscle and other tissues.

1. An acidic protein with properties similar to those of troponin C from rabbit skeletal muscle has been shown to be present in bovine and rabbit smooth muscles, chicken gizzard and rabbit liver, kidney and lung. 2. A simple new method involving the use of organic solvents is described for the purification of the troponin C-like proteins from various tissues. 3. The troponin C-like proteins can be distinguished from rabbit skeletal-muscle toponin C by their electrophoretic behaviour on polyacrylamide gels at pH 8.3 in the presence and absence of Ca2+. The troponin C-like proteins have been shown to form complexes with rabbit skeletal-muscle troponin I that migrate on electrophoresis in polyacrylamide gels. 4. Behaviour on electrophoresis, amino acid analysis and the patterns of CNBr digests on polyacrylamide gels indicate that the troponin C-like proteins from bovine uterus and aorta, rabbit uterus, and liver and chicken gizzard are very similar to, if not identical with, bovine brain modulator protein. 5. With bovine cardiac muscle the organic-solvent method yields a preparation consisting of roughly similar amounts of troponin C and troponin C-like protein. 6. By the isotope-dilution technique, troponin C-like protein has been shown to represent 0.42% of the total protein in rabbit uterus. 7. In homogenates of smooth muscle, rabbit lung, kidney and brain, the troponin C-like proteins form a complex with other protein (or proteins) that requires Ca2+ for its formation and that is not dissociated in 9M-urea.

Amino Acids↗
PubMed1978

Kinetics and regulation of the myofibrillar adenosine triphosphatase.

1. The steady-state kinetic behaviour of the ATPase (adenosine triphosphatase) of intact myofibrils was studied in the presence of both high and low concentrations of Ca2+ (0.25 mM and less than 10 nM respectively). 2. Kinetic data were collected over the initial linear phase of the assay, which lasts for 20--60s. To obtain consistent data we found it necessary to use either fresh myofibril preparations or preparations that had been stored in the presence of thiol compounds. 3. When assayed in the presence of 0.25 mM-Ca2+, the myofibrillar ATPase obeyed Michaelis-Menten kinetics over the range 0.03--5.0 mM-MgATP (Km 16 +/- 6 micrometer, V 0.4 +/- 0.1 mumol/min per mg). 4. At low Ca2+ concentrations (less than 10 nM) the myofibrillar ATPase displayed pronounced substrate inhibition, which was not observed at high Ca2+ concentrations. Thus increasing the MgATP concentration had the net effect of decreasing the ATPase activity at low Ca2+ relative to that at high Ca2+. This preferential effect of MgATP on the low-Ca2+ ATPase may be important in Ca2+ control. 5. The substrate inhibition that was observed at low Ca2+ was lost on storage or thiol modification of the myofibrils. 6. Under physiological conditions (2 mM-MgATP, I 0.15, pH 7.0), the ATPase of fresh and thiol-protected myofibrils displayed approx. 100-fold activation by Ca2+.

Adenosine Triphosphatases↗
PubMed1978

Characterization of a region of the primary sequence of troponin C involved in calcium ion-dependent interaction with troponin I.

1. The CNBr digest of troponin C from rabbit fast skeletal muscle was shown to possess many of the functional properties of the whole troponin C molecule. 2. A peptide corresponding to residues 83-134 was isolated, which forms a Ca(2+-dependent complex with troponin I and neutralizes the inhibition by troponin I of the Mg(2+-stimulated adenosine triphosphatase of desensitized actomyosin. 3. The peptide inhibits the phosphorylation of fast-skeletal-muscle, but not cardiac-muscle, troponin I, by 3' :5'-cyclic AMP-dependent protein kinase. In this property it was as effective as whole skeletal-muscle troponin C when compared on a molar basis. 4. Biological activity was also present in other fractions obtained from the CNBr digest. 5. By gel filtration and affinity chromatography of the whole CNBr digest of troponin C, two peptides, one of which was identified as representing residues 83-134, were shown to form Ca(2+-dependent complexes with troponin I. 6. The significance of these findings for the mechanism of interaction of troponin C and troponin I is discussed.

Adenosine Triphosphatases↗
PubMed1978

Troponin I from human skeletal and cardiac muscles.

1. Myofibrils from human skeletal muscle contained regulatory proteins exhibiting similar electrophoretic behaviour to those present in rabbit skeletal muscle. 2. All human skeletal muscles examined contained two forms of troponin I corresponding to the forms already characterized in fast and slow rabbit muscle. 3. The ratios of the amounts of the two forms of troponin I in different human skeletal muscles were not identical with the ratios for the type 1 to type 2 fibres published in the literature. The ratios could, however, be arranged in the same rank order. 4. Primate heart contained a single form of troponin I different in molecular weight and amino acid composition from the skeletal forms. 5. A monospecific antiserum to human cardiac troponin I was prepared in the sheep and shown not to react with the fast or slow skeletal-muscle forms of troponin I from human and other species. 6. The anti-(human cardiac-muscle troponin I) reacted with the cardiac troponin I from the human, baboon, rabbit and rhesus monkey. Positive reactions were also obtained with urea extracts of whole cardiac tissue.

Amino Acids↗
PubMed1977

The sites of phosphorylation of rabbit cardiac troponin I by adenosine 3':5'-cyclic monophosphate-dependent protein kinase. Effect of interaction with troponin C.

1. Troponin I prepared from rabbit hearts contains 1.0-1.5 mol of P/mol when isolated by affinity chromatography. Most of the covalently bound phosphate is located in residues 1-48 of the molecule. 2. 3':5'-Cyclic AMP-dependent protein kinase catalyses phosphorylation at serine-20 and serine-146. Serine-20 is more rapidly phosphorylated than serine-146. 3. In troponin I prepared from frozen hearts by affinity chromatography about 0.3-0.5 mol of P/mol is associated with serine-20 and 0.8-1.0 mol of P/mol with other site(s) in residues 1-48 of the molecule. 4. Phosphorylation at serine-20 and servine-146 is not significantly inhibited by troponin C. 5. The mechansim of the interaction of troponin C with cardiac troponin I is discussed in the light of these results.

Amino Acids↗
PubMed1977

Purification and properties of myosin light-chain kinase from fast skeletal muscle.

1. A procedure is described for the isolation of myosin light-chain kinase from rabbit fast skeletal muscle as a homogeneous protein. 2. Myosin light-chain kinase is a monomeric enzyme of mol.wt. 77000. Under some conditions of storage it is converted into components of mol.wts. about 50000 and 30000 that possess enzymic activity. 3. The enzyme is clearly different in structure and properties from any other protein kinase so far isolated from muscle. 4. The enzyme is highly specific for the P-light chain (18000-20000-dalton light chain) of myosin and requires Ca2+ for activity. 5. The P-light chain is phosphorylated at a similar rate whether isolated or associated with the rest of the myosin molecule. 6. The effects of pH, bivalent cation and other nucleotides on the enzymic activity are described. 7. The role of the phosphorylation of the P-light chain of myosin in muscle function is discussed.

Animals↗
PubMed1977

Affinity-chromatographic isolation and some properties of troponin C from different muscle types.

1. The formation of a complex between troponin I and troponin C that is stable in 6M-urea and dependent on Ca2+ was demonstrated in extracts of vertebrate striated and smooth muscles. 2. A method using troponin I coupled to Sepharose is described for the rapid isolation of troponin C from striated and smooth muscles of vertebrates. 3. Troponin C of rabbit cardiac muscle differs significantly in amino acid composition from troponin C of skeletal muscle. The primary structures of troponin C of red and white skeletal muscle are very similar. 4. The troponin C-like protein isolated from rabbit uterus muscle has a slightly different amino acid composition, but possess many similar properties to the forms of troponin C isolated from other muscle types. 5. The electrophoretic mobilities of the I-troponin C complexes formed from components isolated from different muscle types are determined by the troponin I component.

Amino Acids↗
PubMed1977

The phosphorylation sites of troponin T from white skeletal muscle and the effects of interaction with troponin C on their phosphorylation by phosphorylase kinase.

1. The phosphorylation of troponin T from rabbit white sketetal muscle is catalysed by phosphorylase kinase, but not at a significant rate by bovine 3':5'-cyclic AMP-dependent protein kinase. 2. The amino acid sequences adjacent to the three major phosphorylation sites of troponin T were determined. 3. The serine in the N-terminal peptide (Asx,SerP, Glx)Glu-Val-Glu, is that phosphorylated (SerP, phosphoserine) when the troponin complex is isolated. 4. The other two sites of phosphorylation are located in the sequence Ala-Leu-(Ser, SerP)-Met-Gly-Ala-Asn-Tyr(Ser,SerP)Tyr. 5. When troponin T is phosphorylated in the presence of troponin C, the extent of phosphorylation at each site is considerably decreased. 6. CNBr fragments of troponin T are also phosphorylated by phosphorylase kinase, but the rate of phosphorylation at each site in the CNBr fragments is considerably slower than in the native protein. 7. From these studies it is suggested that troponin C interacts with troponin T in the region containing the two closely situated phosphorylation sites.

Amino Acid Sequence↗
PubMed1976

Myosin light-chain phosphatase.

1. A method for the isolation of a new enzyme, myosin light-chain phosphatase, from rabbit white skeletal muscle by using a Sepharose-phosphorylated myosin light-chain affinity column is described. 2. The enzyme migrated as a single component on electrophoresis in sodium dodecyl sulphate/polyacrylamide gel at pH7.0, with apparent mol.wt. 70000. 3. The enzyme was highly specific for the phosphorylated P-light chain of myosin, had pH optima at 6.5 and 8.0 and was not inhibited by NaF. 4. A Ca2+-sensitive 'ATPase' (adenosine triphosphatase) system consisting of myosin light-chain kinase, myosin light-chain phosphatase and the P-light chain is described. 5. Evidence is presented for a phosphoryl exchange between Pi, phosphorylated P-light chain and myosin light-chain phosphatase. 6. Heavy meromyosin prepared by chymotryptic digestion can be phosphorylated by myosin light-chain kinase. 7. The ATPase activities of myosin and heavy meromyosin, in the presence and absence of F-actin, were not significantly changed (+/- 10%) by phosphorylation of the P-light chain.

Actins↗