Differential Scanning Calorimetry and CD Spectrometry of Acclimation Temperature-Associated Types of Carp Light Meromyosin

Abstract

Differential scanning calorimetry and CD spectrometry were employed to study the thermal unfolding of light meromyosin (LMM) prepared from carp acclimated to different temperatures. The transition temperatures given by the major peaks at pH 8.0 in 0.6 M KCl for LMM from carp acclimated to 10 degrees C were 32.5 and 39.5 degrees C with the calorimetric enthalpies (DeltaHcal) of 269 and 52 kcal/mol, respectively. LMM from carp acclimated to 20 degrees C exhibited three peaks of transition temperatures at 34.5, 40.2, and 46.9 with DeltaHcal of 152, 20, and 10 kcal/mol, respectively. On the other hand, LMM from carp acclimated to 30 degrees C showed two different patterns. The first experiment gave two transition temperatures at 39.2 and 47.3 degrees C with DeltaHcal of 231 and 39 kcal/mol, respectively. The second series of experiments resulted in showing three peaks of 34.4, 39.5, and 47.5 degrees C with DeltaHcal of 117, 123, and 28 kcal/mol, respectively. N-terminal amino acid sequence analysis revealed that LMM at the second series of experiments with the 30 degrees C-acclimated carp contained component(s) predominant in the 20 degrees C-acclimated carp. Thermal unfolding responsible for these transition temperatures was well explained by melting of alpha-helices which could be determined by far-ultraviolet CD spectroscopy. These results clearly demonstrate that the 30 degrees C-acclimated carp contained the most thermostable LMM.

Effects of urea on surface hydrophobicity of requiem shark myosin

“…Although the process in which α‐helix in rod and its C‐terminal half, L‐meromyosin, unfold by heat treatment has been examined in detail with carp, the unfolding of requiem shark rod by urea is not sufficiently known. 10–12 In conclusion, requiem shark myosin showed almost the same urea concentration dependency to the fluorescence intensity change as that of its rod, whereas the corresponding pattern of carp myosin was similar to that of its S1. These results indicate that shark myosin is more resistant to urea treatments than carp myosin, and that the region connecting S1 and rod is primarily responsible for such differences between requiem shark and carp myosins.…”

Structural Stability of Myosin Rod from Silver Carp as Affected by Season

“…A decrease in the ellipticity upon heating is a useful index for detecting the unfolding process of rods (Samejima and others 1981; Nakaya and others 1997). To understand the difference in the unfolding process between winter and summer rod preparations, we analyzed the unfolding profile as shown in Figure 6.…”

“…It is a temperate freshwater species, so it often experiences large seasonal fluctuations in body temperatures. There have been extensive studies concerning the effects of temperature acclimation on the ATPase activity (Johnston and Goldspink 1975), thermal stability (Heap and others 1985; Huang and others 1990; Nakaya and others 1995, 1997; Kakinuma and others 1998), myosin heavy‐chain gene multiplicity (Watabe and others 1998) in goldfish and common carp. It is reasonable to consider that silver carp muscle contains multiple isoforms of myosin because of the seasonal temperature change.…”

Effect of calcium ion on the thermal denaturation of subfragment-1 and rod regions of squid myosin upon the heating of myofibrils

“…Unfolding of squid myosin rod dissolved in 0.5 M KCl, 20 mM Tris-HCl (pH 7.5) with either 1 mM CaCl 2 or EDTA was measured on JASCO spectropolarimeter J 725 (JASCO, Tokyo) [16,17] using 1mm light path cell. The solution was heated at the raising rate of 1°C/min and the ellipticity at 222 nm upon raising temperature at the rate of 1°C/min was recorded.…”