Differences in Polymer Formation through Disulfide Bonding of Recombinant Light Meromyosin between White Croaker and Walleye Pollack and Their Possible Relation to Species Specific Differences in Thermal Unfolding

Abstract

Fast skeletal light meromyosins (LMMs) of white croaker and walleye pollack were prepared in our expression system using Escherichia coli and determined for their polymer-forming ability and thermodynamic properties by using sodium dodecyl sulfate polyacrylamide gel electrophoresis and differential scanning calorimetry (DSC), respectively. White croaker LMM formed dimer by heating at 80 degrees C and showed only a single peak at 32.1 degrees C of temperature transition in DSC. On the other hand, walleye pollack LMM hardly formed polymer and showed four peaks at 27.7, 30.5, 35.8, and 43.9 degrees C. When Cys525 of white croaker LMM was replaced by alanine, this point-mutated LMM showed no change in its DSC profile but formed no dimer upon heating, suggesting a possible role of Cys525 in dimer formation. On the other hand, walleye pollack LMM where Cys491 was substituted by alanine changed its DSC profile, showing four peaks at 27.9, 29.1, 38.4, and 43.9 degrees C. However, this point-mutated LMM formed no dimer upon heating as in the case of native LMM. These results suggest that cysteine residue(s) participates in thermal gel formation of LMM when it locates in a suitable position of the sequence.

Rheological properties of selected fish paste at selected temperature pertaining to shaping of surimi-based products

“…1). It has been reported that thermodynamic properties of the two myosins and their myosin fragments are also different from each other (Fukushima, Satoh et al, 2003;Fukushima, Yoon, & Watabe, 2003;Fukushima et al, 2005;Togashi, Kakinuma, Nakaya, Ooi, & Watabe, 2002). It is noteworthy that walleye pollack myosin unfolds upon heating at a lower temperature than that of white croaker myosin.…”

Differential Scanning Calorimetry

“…On the other hand, walleye pollack LMM, where Cys491 was substituted by alanine, changed its DSC profi le, showing four peaks at 27.9, 29.1, 38.4 and 43.9 °C. Results suggest that cysteine residue(s) participates in thermal gel formation of LMM when it locates in a suitable position of the sequence (Fukushima et al 2003b).…”

cDNA cloning and complete primary structures of myosin heavy chains from brushtooth lizardfishSaurida undosquamisand wanieso lizardfishS. waniesofast skeletal muscles

“…Fukushima et al 7 . performed point mutation of cysteine at position 525 in white croaker and walleye pollack LMM, demonstrating species‐specific changes in their thermodynamic properties.…”

“…Therefore, the understanding of structure‐function relationship of fish myosins is of importance, although their instability has been attributed to the difficulty of related investigations. Meanwhile, myosin from white croaker Pennahia argentata , one of the most diversified bottom fish, 6 is highly stable in chilling and frozen storage and exhibits the best gel‐forming ability among all fish species 7–10 . Considering such advantageous properties of myosin, this fish appears as a good model to the food technologists for high‐class surimi production 10 .…”

“…Three myosin fragments of white croaker, S1, S2 and LMM, exhibited 79–94% sequence identities to the corresponding fragments of various vertebrates, including walleye pollack. Furthermore, the differences in myosin gel formation between walleye pollack and white croaker were attributed to the species‐specific structural properties of LMM region 6,7,12,13 . Site‐directed mutagenesis revealed that cysteine at position 525 of white croaker LMM is responsible for polymer formation through construction of disulfide‐bridge 7 …”