Use this URL to cite or link to this record in EThOS:
Title: The incorporation of inorganic phosphate by rabbit skeletal muscle
Author: Dean, David Ghulamfarid
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1982
Availability of Full Text:
Access from EThOS:
Access from Institution:
Cheesman and Hilton (1961, 1966) and Cheesman and Whitehead (1969) have demonstrated an uptake of 32P by frog muscle. A reversible 40% reduction in the specific activity of bound P was reported to occur on membrane depolarisation. A similar reduction v/as found by Whitehead (1970) when myofibrils prepared from 32P-labelled rabbitpsoas were contracted. Miihlrad et al. (1963) have shown direct uptake--- of 32P by glycerol-extracted myofibrils and by myosin. The present report attempts to consolidate and expand the above observations. A procedure allowing the resolution of myofibrils into P-containing fractions was developed; several modifications were made to existing methods for P determination. Methods for the direct investigation of myofibrillar ATPase, actomyosin ATPase, adenylate kinase and 5'-AMP deaminase activities in the pH range 7-8 and two methods for the estimation of IMP are presented. A circuit diagram for an integrator of pulses from a radioactivity counter is given. An appendix contains practical details of these methods. The possibility was excluded that ATP synthesised from actin-bound ADP during water extraction of acetone-dried muscle derived its y-phosphate group from a source other than the adenylate kinase reaction proposed by Tsuboi (1963). Changes in concentrations of ATP, ADP, AMP and IMP during the extraction were found to be consistent with adenylate kinase and 5'-AMP deaminase activities. Contaminating bacteria were shown to be responsible for direct uptake of 32P by myofibrils and myosin. The reduction, on contraction, in the specific activity of bound 32P in myofibrils prepared from labelled psoas was related to a decrease in extractability of protein from contracted myofibrils. Label was3distributed throughout the P-containing fractions although the nucleotides showed very low activity. Application of myofibrils to polyacrylamide gels yielded several labelled bands. A new role for methylated amino acid residues in muscle is proposed. The roles of adenylate kinase and 5'-AMP deaminase and a contraction mechanism involving the reversible phosphorylation of actin-bound ADP are considered.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physiology