Format

Send to

Choose Destination
Biophys J. 1998 Jun;74(6):3044-58.

ATP analogs and muscle contraction: mechanics and kinetics of nucleoside triphosphate binding and hydrolysis.

Author information

1
Department of Physiology, School of Medicine, University of California, Los Angeles 90095, USA.

Abstract

The mechanical behavior of skinned rabbit psoas muscle fiber contractions and in vitro motility of F-actin (Vf) have been examined using ATP, CTP, UTP, or their 2-deoxy forms (collectively designated as nucleotide triphosphates or NTPs) as contractile substrates. Measurements of actin-activated heavy meromyosin (HMM) NTPase, the rates of NTP binding to myosin and actomyosin, NTP-mediated acto-HMM dissociation, and NTP hydrolysis by acto-HMM were made for comparison to the mechanical results. The data suggest a very similar mechanism of acto-HMM NTP hydrolysis. Whereas all NTPs studied support force production and stiffness that vary by a factor 2 or less, the unloaded shortening velocity (Vu) of muscle fibers varies by almost 10-fold. 2-Deoxy ATP (dATP) was unique in that Vu was 30% greater than with ATP. Parallel behavior was observed between Vf and the steady-state maximum actin-activated HMM ATPase rate. Further comparisons suggest that the variation in force correlates with the rate and equilibrium constant for NTP cleavage; the variations in Vu or Vf are related to the rate of cross-bridge dissociation caused by NTP binding or to the rate(s) of product release.

PMID:
9635759
PMCID:
PMC1299646
DOI:
10.1016/S0006-3495(98)78012-9
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center