The Effects of Pressure on F-G Transformation of Actin^*

Some Effects of Pressure Treatment on Actomyosin Systems

“…The large decrease in the relative viscosity of actin as a result of pressurization is consistent with a depolymerization of F-actin as has been observed by other workers (Ikkai and Ooi 1966). Therefore both the major constituent proteins of actomyosin probably disaggregate under pressure, although as mentioned above myosin presumably aggregated following release of pressure.…”

“…This could be a consequence of destruction of interactions between myosin molecules, as mentioned above, or of actin molecules, or as suggested by Ivanov et al (1960), by the splitting of actomyosin into actin and myosin components. However, this splitting does not seem likely to occur; Ikkai and Ooi (1969), from studies on synthetic heavy actomeromyosin, suggest that this material does not simply dissociate under pressure into actin and heavy meromyosin.…”

“…However, they found that pressurization resulted in an increase in the molecular weight of myosin in 0·6 M KCl solution and suggested that under pressure actomyosin splits into its components. Ikkai and Ooi (1966) found that F-actin in the absence of ATP started to undergo irreversible denaturation at a pressure of c. 1500 kg/cm 2 (147 MN/m 2 ), and complete denaturation at 3000 kg/cm 2 (294 MN/m 2 ). They found evidence for the transformation of F-to G-actin under the influence of pressure.…”

“…They found evidence for the transformation of F-to G-actin under the influence of pressure. Ikkai and Ooi (1969) reported that turbid solutions of actomyosin and heavy actomeromyosin became transparent with increasing pressure, finally to give constant intensities of transmitted light at c. 2000 kg/cm 2 (196 MN/m 2 ). The effects of pressure on actomyosin systems were accounted for in terms of depolymerization or dissociation of protein components.…”

Comparative sequence analysis of myosin heavy chain proteins from congeneric shallow- and deep-living rattail fish (genus Coryphaenoides)

“…Although many previous studies have identified proteins from deep-sea fish that function at high hydrostatic pressure, only α-actin protein has been examined at the level of the amino acid sequence (Morita, 2000;Morita, 2003). The polymerization of globular (G)-actin to filamentous (F)-actin is accompanied by an increase in total volume (Ikkai and Ooi, 1966). Interestingly, the increase in volume with the polymerization of α-actin from two deep-sea fishes, C. armatus and C. yaquinae, is much smaller than that from non-deep-sea fishes, C. acrolepis and C. cinereus, which is advantageous for a deep-sea environment (Morita, 2003;Swezey and Somero, 1985).…”