MedicGo
Radioactive labeling and location of specific thiol groups in myosin from fast, slow and cardiac muscles.
Metadata
JournalBiochim. Biophys. ActaNot FoundDate
1975-Nov-20
Publication Type
Journal Article
Volume
1975-Nov-20 / 410 : 193-209
Author
Pfister M , Schaub MC , Watterson JG , Knecht M , Waser PG
DoiPMIDMESH
Adenosine Triphosphatases
Animals
Binding Sites
Enzyme Activation
Ethylmaleimide
Hydrogen-Ion Concentration
Kinetics
Magnesium
Molecular Weight
Muscle, Smooth
Muscles
Myocardium
Myosins
Potassium
Protein Binding
Protein Conformation
Rabbits
Sulfhydryl Compounds
Swine
Temperature
Abstract
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.
Fav
Like
Download
Share
Export
Cite
B
Biochim. Biophys. ActaBiochimica et biophysica acta
Metadata
Location
From

No Data

© 2017 - 2020 Medicgo
Powered by some medical students