Fazekas S, Berentey G, Fehér G, Székessy-Hermann V
Second Institute of Biochemistry, Semmelweis University Medical School, Budapest, Hungary.
Acta Physiol Hung. 1988;71(2):183-201.
In this report a summary is given of our experiments concerning the in vivo endogenous phosphate (P) content of myosin. It was found that besides the ester type phosphates of myosin there was a considerable amount of N-P type energy-rich phosphoryl groups bond to the basic amino acids of peptide chains. The endogenous P concentration of myosin depends on the source of the preparation. The concentration of P is much higher in myosin preparations of well-trained animals and human subjects compared to those found in the control muscles. As the P binding sites of fresh purified myosin are only partially saturated, the preparations can incorporate P up to a definite saturation only. The phosphorylating ability of myosins disappears after prolonged storage as a consequence of an alteration in structure of the myosin molecule. The P groups are moving inside the myosin molecule. It is supposed that the inorganic P release promoted by actin is connected with the thin filament movements towards the centre of the sarcomere, furthermore P replenishment, P linking and movement involve N3-trimethyl-lysine, 3-methylhistidine, P-Arg and two conformers of P-His. The two net negative charges of P group form electric monopoles of a minor battery (myosin head). They help to force generation at head rotation (90 degrees-45 degrees angle) and produce free energy changes that can be calculated from the number of N-P bonds.
本报告总结了我们关于肌球蛋白体内内源性磷酸盐（P）含量的实验。发现除了肌球蛋白的酯型磷酸盐外，还有相当数量的N - P型富含能量的磷酰基与肽链的碱性氨基酸结合。肌球蛋白的内源性P浓度取决于制备来源。与对照肌肉相比，训练有素的动物和人类受试者的肌球蛋白制剂中的P浓度要高得多。由于新鲜纯化的肌球蛋白的P结合位点仅部分饱和，制剂只能结合P直至达到一定饱和度。由于肌球蛋白分子结构的改变，长时间储存后肌球蛋白的磷酸化能力消失。P基团在肌球蛋白分子内部移动。据推测，肌动蛋白促进的无机P释放与细肌丝向肌节中心的移动有关，此外，P的补充、连接和移动涉及N3 - 三甲基赖氨酸、3 - 甲基组氨酸、P - 精氨酸和P - 组氨酸的两种构象体。P基团的两个净负电荷形成一个小电池（肌球蛋白头部）的电单极子。它们有助于在头部旋转（90度 - 45度角）时产生力，并产生可根据N - P键数量计算的自由能变化。
