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The effect of troponin C removal on the Ca 2+ ‐sensitive binding of Mg 2+ AMPPNP to myofibrils
Author(s) -
Johnson Robert E.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80755-5
Subject(s) - myofibril , steric effects , titration , chemistry , troponin c , biophysics , ethylene glycol , dissociation constant , sarcomere , ethylene , dissociation (chemistry) , troponin , crystallography , stereochemistry , biochemistry , biology , inorganic chemistry , organic chemistry , myocyte , medicine , myocardial infarction , receptor , endocrinology , catalysis
It was previously shown that when rabbit skeletal myofibrils are titrated with Mg 2+ AMPPNP under conditions that result in the dissociation of cross‐bridges from the thin filaments (i.e. 50% ethylene glycol, O°C), Ca 2+ ‐sensitive, biphasic binding is observed. These titrations have been repeated using myofibrils from which the troponin C has been selectively removed. The disappearance of both Ca 2+ sensitivity and biphasic binding is taken as evidence that the Ca 2+ sensitivity is due to Ca 2+ binding to troponin C and the biphasic binding of Mg 2+ AMPPNP observed in intact myofibrils is not due to packing constraints or steric hindrance.