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Biomedical subjects

S V Perry

Publications and source records attributed to S V Perry.

At least 127 records · Page 7Linked to original sources
PubMed1971

The regulatory proteins of the myofibril. Characterization and properties of the inhibitory factor (troponin B).

1. Gel-filtration results indicate that the major component of inhibitory-factor preparations isolated by dissociation of the troponin complex consisted of a protein of subunit weight 23000 daltons. By the same procedure a molecular weight of 18000 was obtained for the calcium-sensitizing factor. 2. The inhibitory factor is specific for the actomyosin type of ATPase and ITPase. It is effective on desensitized actomyosin, natural actomyosin and intact myofibrils. 3. For inhibition, the actomyosin ATPase must be stimulated by Mg(2+), Ca(2+) or Mn(2+). The Co(2+)-, Cd(2+)- or Zn(2+)-stimulated ATPases are not affected. 4. Biological activity is stable to treatment with dissociating agents, heat, pH11, pH1 and carboxymethylation. 5. Increasing amounts of actin, but not myosin or tropomyosin, progressively neutralize the inhibitory activity when added to desensitized actomyosin or myofibrils.

Actins↗
PubMed1970

An electrophoretic study of the low-molecular-weight components of myosin.

1. The low-molecular-weight components of myosin freshly prepared by the standard procedure from adult rabbit skeletal muscle migrated as four main bands Ml(1), Ml(2), Ml(3) and Ml(4) on polyacrylamide-gel electrophoresis in 8m-urea. 2. The number of bands increased on storage. This change was accelerated by increasing the temperature and pH. 3. None of the bands had electrophoretic mobilities identical with those of the well-characterized proteins of the myofibril or with the sarcoplasmic proteins. 4. By varying the ionic conditions and concentration of muscle mince used for the initial extraction it was possible to change the relative proportions of the two electrophoretic bands of intermediate mobility, Ml(2) and Ml(3). 5. The four-band picture similar to that obtained with rabbit was observed with myosin isolated from skeletal muscle of the rat, mouse, hamster, pigeon and chicken. 6. Rabbit cardiac myosin gave only two bands on electrophoresis. Myosin from rabbit red muscle gave a pattern intermediate between cardiac and white-skeletal-muscle myosin, i.e. the two fastest bands were present in decreased relative amounts. 7. It is suggested that the differences in the low-molecular-weight components of myosin from different types of muscle are a consequence of differences in the isoenzyme composition of the myosins.

Animals↗
PubMed1970

Biological activity and the 3-methylhistidine content of actin and myosin.

1. The 3-methylhistidine content of myosin varies according to muscle type. It is highest in myosin from white skeletal muscle and lower values are obtained from myosin of red skeletal and smooth muscle. 2. The 3-methylhistidine content of actin was similar in all of the types of muscle from which it was isolated. 3. The 3-methylhistidine of rabbit actin is localized in a single tryptic peptide that was readily modified during fractionation procedures. 4. Photo-oxidation studies indicated that the 3-methylhistidine residues are not essential for adeonsine triphosphatase and actin-combining activities of myosin. 5. During photooxidation G-actin lost completely the ability to polymerize to the F form before all the 3-methylhistidine was destroyed.

Adenosine Triphosphatases↗
PubMed1970

Occurrence and formation of the N epsilon-methyl-lysines in myosin and the myofibrillar proteins.

1. Adult rabbit skeletal-muscle myosin has been shown to contain 1.0 residue of mono-N(in)-methyl-lysine and 3.3 residues of tri-N(in)-methyl-lysine per molecule of molecular weight 500000. 2. The methyl-lysines appear to be located in the subfragment 1 portion of the myosin molecule. 3. Methyl-lysines are not present in actin, tropomyosin, inhibitory factor and calcium-sensitizing factor. 4. Enzymic methylation of histidine and lysine residues of myosin has been demonstrated in vitro. 5. The methylation of histidine and lysine of the total myofibrillar protein occurs after peptide-bond synthesis. 6. Although methylated lysines and 3-methyl-histidine could not be detected by analysis of hydrolysates, radiochemical evidence is provided for the presence of these residues in the soluble-protein fraction of rabbit skeletal muscle.

Amino Acids↗
PubMed1969

The adenosine triphosphatase and calcium ion-transporting activities of the sarcoplasmic reticulum of developing musce.

1. The ATPase (adenosine triphosphatase) specific activity and the total nitrogen content of the myofibrillar fraction per g. wet weight of rabbit longissimus dorsi muscle increased steadily during the late foetal stages and the first few weeks after birth. 2. The ATPase specific activity of the sarcoplasmic-reticular fraction isolated by a sucrose-density-gradient procedure rose to a sharp peak 8-10 days after birth and then declined to the adult value, which was about 25% of the maximum. 3. The peak in ATPase activity was a feature of the sarcoplasmic reticulum isolated from muscle, and the time at which it occurred in relation to birth was related to the degree of development and the activity pattern of the muscle. 4. The peak in ATPase activity of the sarcoplasmic reticulum occurred at an earlier age if newborn animals were made to exercise earlier than was normal. 5. The ;extra' ATPase associated with the sarcoplasmic reticulum and the ability to concentrate Ca(2+) increased in a similar manner over the period of development studied. 6. It is postulated that the Ca(2+)-transport system of the sarcoplasmic reticulum consists of two components, namely the ATPase and the system coupling this enzyme to Ca(2+) transport. During development the ATPase develops first and has almost reached maximum activity in the longissimus dorsi muscle of the rabbit after 8-10 days. Subsequently the activity of the coupling system rises rapidly, leading to an increase in the capacity and efficiency of Ca(2+) transport.

Adenosine Triphosphatases↗
PubMed1969

The relaxing protein system of striated muscle. Resolution of the troponin complex into inhibitory and calcium ion-sensitizing factors and their relationship to tropomyosin.

1. A method involving isoelectric precipitation and chromatography on SE-Sephadex (sulphoethyl-Sephadex) is described for the preparation of the troponin complex free of tropomyosin from low-ionic-strength extracts of natural actomyosin and myofibrils. 2. Purified troponin complex required tropomyosin to inhibit the Mg(2+)-stimulated adenosine triphosphatase activity and superprecipitation of desensitized actomyosin in the presence of ethanedioxybis(ethylamine)tetra-acetate. An upper limit of 35000 for the ;molecular weight' of the troponin complex was derived from the amounts required to bring about 50% of the maximum inhibition of the Mg(2+)-stimulated adenosine triphosphatase activity of desensitized actomyosin of known concentration. 3. In the presence of dissociating reagents the troponin complex could be dissociated into inhibitory and Ca(2+)-sensitizing factors, which could be isolated separately on SE-Sephadex. The inhibitory factor inhibited the Mg(2+)-stimulated adenosine triphosphatase activity and superprecipitation of desensitized actomyosin independently of the concentration of free Ca(2+) in the medium. 4. The Ca(2+)-sensitizing factor changed its electrophoretic mobility on polyacrylamide gel in the presence of ethanedioxybis(ethylamine)tetra-acetate. It formed a complex with the inhibitory factor at low ionic strength and the original biological activity of the troponin complex could be restored on mixing the inhibitory factor with the Ca(2+)-sensitizing factor in the ratio of about 3:2. 5. Evidence is presented indicating that the ability of tropomyosin preparations to restore relaxing-protein-system activity to the troponin complex and their inhibitory effect on the Ca(2+)-stimulated adenosine triphosphatase activity of desensitized actomyosin are two properties of different stability to preparative procedures and tryptic digestion. This suggests that the relaxing protein system of muscle may contain another as yet uncharacterized component.

Adenosine Triphosphatases↗
PubMed1968

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.

Amino Acid Sequence↗