In order to elucidate the mechanisms involved in actomyosin denaturation induced by urea, changes in surface hydrophobicity were examined using sodium 8-anilino-1-naphthalene sulfonate as a fluorescent dye. With increase of urea concentration up to 2M, white-fleshed fish actomyosins showed a marked increase of hydrophobicity. Red-fleshed fish and elasmobranch actomyosins exhibited a less increase, whereas avian and mammalian actomyosins did not at all. The urea-induced hydrophobicity increase was to some extent suppressed by sucrose.
Based on these results, it was concluded that the intramolecular hydrophobic interaction in actomyosin is most weak with the white-fleshed fish, followed by red-fleshed and elasmobranch fish, and warm-blooded animal.
