Lower activation energy for sliding of F-actin on a less thermostable isoform of carp myosin.
We have examined the temperature-dependence of sliding velocity of fluorescent F-actin on myosins isolated from 10 degrees C- and 30 degrees C-acclimated carp. Activation energies for the sliding of F-actin were 63 and 111 kJ/mol for the 10 degrees C- and 30 degrees C-acclimated carp myosins, respectively. Arrhenius plots of the sliding velocity from 10 degrees C- and 30 degrees C-acclimated carp myosin were shown to intersect at high temperature (about 30 degrees C). The thermostability estimated by measuring the Ca(2-)-ATPase activity was less for myosin from 10 degrees C- than 30 degrees C-acclimated carp. We suggest that a less thermostable structure in cold-acclimated carp myosin results in a reduced activation energy for the contractile process, which allows the F-actin to slide fast even at low temperatures.
Chaen
S
S
Department of Physiology, School of Medicine, Teikyo University, Tokyo. chaen@med.teikyo-u.ac.jp
Nakaya
M
M
Guo
X F
XF
Watabe
S
S
D000064:Acclimatization / Q000502:physiology*; D000199:Actins / Q000737:chemistry; D000818:Animals; D002347:Carps / Q000502:physiology*; D066298:In Vitro Techniques; D008124:Locomotion / Q000502:physiology; D009124:Muscle Proteins / Q000737:chemistry* / Q000502:physiology; D009218:Myosins / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics
D000199:Actins; D009124:Muscle Proteins; D009218:Myosins