Summary
(1) By means of a simple method the conditions were investigated for contraction and relaxation of actomyosin (AM) under the influence of potassium, magnesium, and calcium ions, of adenosintriphosphate (ATP) or muscle-adenylic-acid and phosphocreatin.
(2) Raising the calcium chloride concentration to 0.2 m and raising thep H from 6.9 to 7.3 hinders the contraction of actomyosin by ATP; in uncontracted AM-gel, ATP leads to a relaxation under these conditions.
(3) Relaxation of the contracted gel can be brought about by dissolving in potassium chloride and precipitating by dilution: calcium furthers this relaxation; afterward ATP leads again to a contraction.
(4) Remainders of ATP from the first contraction lead in this stage again to a partially contracted gel; phosphocreatin reinforces this effect.
(5) Certain SH-groups and amino groups, but not carboxyl groups, are involved in the production of the contraction.
(6) SH- and amino groups are also necessary for the ATP-ase effect. The relation of actomyosin-ATP-ase to contraction, of myosin-ATP-ase to relaxation is pointed out.
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Kuschinsky, G., Turba, F. Über den Chemismus von Zustandsänderungen des Aktomyosins. Experientia 6, 103–106 (1950). https://doi.org/10.1007/BF02153375
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DOI: https://doi.org/10.1007/BF02153375