兔腰大肌甘油化肌纤维在Mg-ITP溶液中张力发展的温度依赖性。

Temperature-dependence of tension development by glycerinated muscle fibers of rabbit psoas in Mg-ITP solution.

作者信息

Yoshida A, Hozumi T, Tawada K

出版信息

J Biochem. 1977 Aug;82(2):495-8.

Abstract

The isometric tension of single fibers isolated from glycerinated rabbit psoas muscle was measured at various temperatures using Mg-ITP as a substrate. The tension developed in Mg-ITP decreased linearly as the temperature was reduced from 24 degrees C to 4 degrees C. Myosin formed the myosin--product complex predominantly via ATP hydrolysis at the burst site during Mg-ATP hydrolysis, irrespective of temperature, and the tension developed in Mg-ATP decreased linearly as the temperature decreased (Yoshida and Tawada (1976) J. Biochem. 80, 861). During Mg-ITP hydrolysis, myosin forms the myosin*-product complex predominantly at the burst site above 20 degrees C, while myosin forms the myosin*-substrate complex below 8 degrees C (Hozumi (1976) Eur. J. Biochem. 63, 241). However, the temperature dependence of tension development in Mg-ITP is linear, as with Mg-ATP, as mentioned above. This temperature dependence is not compatible with some muscle models which assume the formation of the myosin*-product complex by cross-bridges prior to combination with actin during contraction.

摘要

使用Mg-ITP作为底物，在不同温度下测量从甘油处理的兔腰大肌分离出的单纤维的等长张力。当温度从24℃降至4℃时，Mg-ITP中产生的张力呈线性下降。在Mg-ATP水解过程中，无论温度如何，肌球蛋白主要通过在爆发位点的ATP水解形成肌球蛋白 - 产物复合物，并且随着温度降低，Mg-ATP中产生的张力呈线性下降（吉田和田田（1976年）《生物化学杂志》80卷，861页）。在Mg-ITP水解过程中，肌球蛋白在20℃以上主要在爆发位点形成肌球蛋白* - 产物复合物，而在8℃以下肌球蛋白形成肌球蛋白* - 底物复合物（小泉（1976年）《欧洲生物化学杂志》63卷，241页）。然而，如上所述，Mg-ITP中张力发展的温度依赖性与Mg-ATP一样呈线性。这种温度依赖性与一些肌肉模型不相符，这些模型假设在收缩过程中，肌球蛋白* - 产物复合物在与肌动蛋白结合之前由横桥形成。