The incorporation of inorganic phosphate by rabbit skeletal muscle

Dean, David Ghulamfarid

(1982)

Dean, David Ghulamfarid (1982) The incorporation of inorganic phosphate by rabbit skeletal muscle.

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Abstract

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.

Information about this Version

This is a Accepted version
This version's date is: 1982
This item is not peer reviewed

Link to this Version

https://repository.royalholloway.ac.uk/items/8597316f-7e88-4236-a282-6112e02c62f4/1/

Item TypeThesis (Doctoral)
TitleThe incorporation of inorganic phosphate by rabbit skeletal muscle
AuthorsDean, David Ghulamfarid
Uncontrolled KeywordsPhysiology; Biological Sciences; Incorporation; Inorganic; Muscle; Phosphate; Phosphorus Uptake; Phosphorus Uptake; Rabbit; Skeletal
DepartmentsDepartment of Biochemistry

Identifiers

ISBN978-1-339-63010-6

Deposited by () on 01-Feb-2017 in Royal Holloway Research Online.Last modified on 01-Feb-2017

Notes

Digitised in partnership with ProQuest, 2015-2016. Institution: University of London, Bedford College (United Kingdom).


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