EFFECT OF SALTS AND OF ADENOSINE 5'-TRIPHOSPHATE ON SHORTENING OF GLYCERINATED MUSCLE FIBERS

Studies of the length-temperature-composition relations for a glycerinated muscle fiber (rabbit psoas) in various salt solutions and in ATP are reported. Despite the morphological complexities inherent to this fibrous system, complete shortening is shown to be a consequence of a cooperative structural transition similar to that observed with the other fibrous proteins. The results obtained with the salt solutions help establish the transition temperature in the absence of added monomeric species, i.e., in pure water. Under these conditions, the transition occurs at an elevated temperature. It is, however, found that this transition temperature is lowered mono-tonically with the addition of increasing amounts of ATP. Complex transition temperature-composition relations are observed when the supernatant solution contains either Mg2+ or Ca2+ in conjunction with ATP. © 1969, American Chemical Society. All rights reserved.