Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles

M Pfister; M C Schaub; J G Watterson; M Knecht; P G Waser

Back

Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles

Journal article

Peer reviewed

Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles

M Pfister, M C Schaub, J G Watterson, M Knecht and P G Waser

Biochimica et biophysica acta, Vol.410(1), pp.193-209

11/20/1975

Handle:

https://hdl.handle.net/2376/101272

PMID: 73

Abstract

Rabbits

Temperature

Molecular Weight

Enzyme Activation - drug effects

Magnesium - pharmacology

Potassium - pharmacology

Sulfhydryl Compounds - analysis

Myocardium - enzymology

Animals

Muscles - enzymology

Adenosine Triphosphatases - analysis

Swine

Myosins - analysis

Protein Binding

Ethylmaleimide - pharmacology

Myosins - metabolism

Protein Conformation

Kinetics

Binding Sites

Hydrogen-Ion Concentration

Muscle, Smooth - enzymology

1. Based on incorporation of radioactively labeled N-ethylmaleimide, the readily reactive thiol groups of isolated myosin (EC 3.6.1.3) from fast, slow and cardiac muscles could be classified into 3 types. All 3 myosins contain 2 thiol-1, 2 thiol-2 and a variable number of thiol-3 groups per molecule. Both thiol-1 and thiol-2 groups which are essential for functioning of the K+-stimulated ATPase, are located in the heavy chains in all 3 myosin types. 2. The variation in the incorporation pattern of N-ethylmaleimide over the 3 thiol group classes under steady-state conditions of Mg(2+) - ATP hydrolysis allowed different conformations of some reaction intermediates to be characterized. In all 3 types of myosin the hydrolytic cycle of Mg(2+) - ATP was found to be controlled by the same step at 25 degrees C. In all three cases, this rate-limiting step is changed in the same way by lowereing temperature. 3. Using the chemically determined molecular weights for myosin light chains, their stoichiometry was found on the basis of sodium dodecyl sulfate electrophoresis to be 1.2 : 2.1 : 0.8 for light chain-1: light chain-2:light chain-3 per molecule of fast myosin, 2.0 : 1.9 for light chain-1:light chain-2 per molecule of slow myosin and 1.9 : 1.9 for light chain-1:light chain-2 per molecule of cardiac myosin. This qualitative difference in light subunit composition between the fast and the two types of slow myosin is not reflected in the small variations of the characteristics exhibited by the isolated myosins, but rather seems to be connected with their respective myofibrillar ATPase activities.

Metrics

5 Record Views

Details

Title: Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles
Creators: M Pfister
M C Schaub
J G Watterson
M Knecht
P G Waser
Publication Details: Biochimica et biophysica acta, Vol.410(1), pp.193-209
Publisher: Netherlands
Grant note: SF19107 / Biotechnology and Biological Sciences Research Council
Identifiers: 99900546505401842
Language: English
Resource Type: Journal article

Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles

Related links

Abstract

Metrics

Details