ISSN:
1432-136X
Keywords:
Crossbridge motions
;
Dynamic light scattering
;
Seasonal changes
;
Muscle
;
Thick filament
;
Limulus polyphemus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary In dynamic light scattering, measurements of the intensity-intensity time correlation function from a suspension of rod-like particles of length L could reveal dynamical information related to translational and internal motions of those particles. For a suspension of thick filaments isolated from the myosin-regulated, striated muscles of Limulus at KL〉1 (where K is the scattering vector), the average characteristic linewidth ( $$\bar \Gamma$$ ) increased with the addition of Ca2+ or with the depletion of ATP. The increase in the $$\bar \Gamma$$ with the addition of Ca2+ could be due to the presence of energy-requiring, high-frequency motions of the crossbridges activated by Ca2+. The increase in $$\bar \Gamma$$ which occurred with the depletion of ATP was assumed to be mainly due to the thermal motions of the crossbridges after they had moved radially away from the filament backbone. The percentage increase in $$\bar \Gamma$$ following the addition of Ca2+ was found to be seasonal, i.e., values of $$\bar \Gamma$$ obtained from thick filaments isolated between the middle of June and the middle of September were smaller than those obtained during the rest of the year. The effect of temperature on the percentage increase in $$\bar \Gamma$$ was also different. The increase showed a maximum at about 35°C during the summer and at about 25°C at other times. However, the percentage increase in $$\bar \Gamma$$ developed under ATP-depleted conditions showed no temperature-related maximum. The number of bound Ca2+ per myosin molecule was 1 during the summer and 2 at other times.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00264810
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