title: Complex formation between regulatory and essential light chain on squid mantle myosin subfragment-1 revealed by thermal denaturation method.
abstract: Thermal treatment of squid myosin subfragment-1 (S-1) in the presence of EDTA results in a rapid inactivation of ATPase, a marked turbidity increase, and a dissociation of light chains. These effects were suppressed by addition of calcium ion. Different light chain binding in EDTA-medium from that in Ca-medium was demonstrated by the tryptic digestion of native squid S-1; the two types of light chain are both resistant to trypsinolysis in Ca-medium, whereas they are readily degraded in EDTA-medium. S-1 heavy chain was converted into three fragments with sizes of 27, 47, and 22 kDa in both media. However, trypsinolysis of S-1 inactivated in Ca-medium generated no such heavy chain fragments that survived, while the two types of light chain survived. These light chains were isolated as a complex lacking any heavy chain fragments, and the complex formation was Ca-sensitive. It is concluded that regulatory and essential light chains are present on S-1 as a complex whose formation is mediated by calcium ion, and this binding might alter the S-1 conformation so as to confer resistance to thermal treatment.
authors.affiliation: Department of Food Science, Faculty of Fisheries, Hokkaido University.
authors.forename: K
authors.initials: K
authors.lastname: Konno
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D049832:Decapodiformes / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D006358:Hot Temperature; D006868:Hydrolysis; D008970:Molecular Weight; D015879:Myosin Subfragments / Q000737:chemistry* / Q000502:physiology; D009218:Myosins / Q000502:physiology*; D009391:Nephelometry and Turbidimetry; D010455:Peptides / Q000032:analysis; D011489:Protein Denaturation; D014357:Trypsin
chemical_list: D015879:Myosin Subfragments; D010455:Peptides; D004492:Edetic Acid; D014357:Trypsin; D000251:Adenosine Triphosphatases; D009218:Myosins; D002118:Calcium