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Myofibrils of skeletal muscle: The activity coefficient of orthophosphate
Author(s) -
Grazi Enrico,
Adami Raffaella,
Magri Ermes,
Trombetta Giorgio,
Frassinefi Chiara
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700203781
Subject(s) - myofibril , skeletal muscle , molality , chemistry , dissociation constant , biochemistry , biophysics , anatomy , biology , organic chemistry , aqueous solution , receptor
In the myofibrils of skeletal muscle, at 22°C, pH 7.1 and at the physiological protein osmotic pressure of 1.8×105 dynes/cm2, orthophosphate behaves quite ideally, the activity coefficient being 0.85. Under the same conditions and at saturation, 2.67 μ moles of orthophosphate are bouud per gram of dry myofibrils, with a dissociation constant of 7×10‐5 molal. Work is in progress to determine the activity coefficients of adenine nucleotide analogues. This work is needed to assess the actual value of the free energy of hydrolysis of ATP in muscle.