摘要:

Summary.In confirmation of Szent‐Gyorgyiet al. we find that ATP causes a strong volume constriction in myosin threads. This effect occurs in threads prepared both from enzymatically active and practically inactive myosin.Adenosine diphosphate and inosine triphosphate which release contraction in the muscle fibre, are without effect on the myosin thread.Birefringence decreases considerably during the shortening produced by ATP, while it increases when shortening is prevented.Sulfhydryl reagents reduce the changes in volume and birefringence produced by ATP in the myosin thread and also make a muscle fibre less excitable by ATP and electrical stimuli.Creatine phosphate, sodium triphosphate, sodium pyrophosphate and sodium ortophosphate, ineffective as such, likewise reduce the effect of ATP, while it is enhanced by inosine triphosphate.Previous treatment with acetylcholine reduces the effect of ATP only in enzymatically inactive dried myosin threads.Threads which show a strong shortening ability towards ATP in a tensionless condition, react with a considerable decrease in stiffness and increase in equilibrium length even at loads which in the untreated thread only produce a stretch of 0.1 per cent. Both effects are interpreted as being due to the release of a certain proportion of elastically active linkages in the minute structural elements by ATP.The work has been supported by theMichaelsen Fond, Nordisk Insulin Fondand OverretssagforerL. Zeuthens Mindelega

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1947.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY