Author | Frisbie, S.M. | |
Author | Xu, S. | |
Author | Chalovich, Joseph | |
Author | Yu, L.C. | |
Date Accessioned | 2021-03-15T12:30:39Z | |
Date Available | 2021-03-15T12:30:39Z | |
Date of Issue | 1998-06 | |
Identifier (URI) | http://hdl.handle.net/10342/8876 | |
Description | Several earlier studies have led to different conclusions about the complex of myosin with MgAMP-PNP. It has been suggested that subfragment 1 of myosin (S1)-MgAMP-PNP forms an S1-MgADP-like state, an intermediate between the myosin S1-MgATP and myosin S1-MgADP states or a mixture of cross-bridge states. We suggest that the different states observed result from the failure to saturate S1 with MgAMP-PNP. At saturating MgAMP-PNP, the interaction of myosin S1 with actin is very similar to that which occurs in the presence of MgATP. 1) At 1°C and 170 mM ionic strength the equatorial x-ray diffraction intensity ratio I11/I10 decreased with an increasing MgAMP-PNP concentration and leveled off by ∼20 mM MgAMP-PNP. The resulting ratio was the same for MgATP-relaxed fibers. 2) The two dimensional x-ray diffraction patterns from MgATP-relaxed and MgAMP-PNP-relaxed bundles are similar. 3) The affinity of S1-MgAMP-PNP for the actin-tropomyosin-troponin complex in solution in the absence of free calcium is comparable with that of S1-MgATP. 4) In the presence of calcium, I11/I10 decreased toward the relaxed value with increasing MgAMP-PNP, signifying that the affinity between cross-bridge and actin is weakened by MgAMP-PNP. 5) The degree to which the equatorial intensity ratio decreases as the ionic strength increases is similar in MgAMP-PNP and MgATP. Therefore, results from both fiber and solution studies suggest that MgAMP-PNP acts as a non hydrolyzable MgATP analogue for myosin. | en_US |
Language | en_US | en_US |
Related URI | https://www.sciencedirect.com/science/article/pii/S0006349598780142?via%3Dihub | en_US |
Subject | AMP-PNP5′-adenylylimido-diphosphate | en_US |
Title | Characterizations of Cross-Bridges in the Presence of Saturating Concentrations of MgAMP-PNP in Rabbit Permeabilized Psoas Muscle | en_US |
Type | Article | en_US |
Identifier (DOI) | https://doi.org/10.1016/S0006-3495(98)78014-2 | |
Journal Name | Biophysical Journal | en_US |
Journal Volume | 74 | en_US |
Journal Issue | 6 | en_US |
Article Pages | 3072-3082 | en_US |