title: The reactivity and function of thiol groups in trout actin.
abstract: 1. Considerable differences were found between the rates and degrees of modification of native trout actin with iodo[2-(14)C]acetate and iodo[1-(14)C]acetamide. 2. With iodoacetate, G- and F-actin were both labelled in the N-terminal peptide only. This modification had little effect on the ability of the actin to polymerize. 3. Iodoacetamide labelled three cysteine residues in both G- and F-actin. The modified cysteine residues were identified from the position of the corresponding tryptic peptides on peptide ;maps'. 4. The modification had little effect on the ability of G-actin to polymerize, to bind ATP or to bind Ca(2+), or on the ability of F-actin to depolymerize. 5. It is concluded that the three cysteine residues present on the ;surface' of the native trout actin molecule have no direct role in the polymerization processes, the binding of ATP, or the binding of Ca(2+).
mesh_terms: D000081:Acetamides; D000199:Actins; D000255:Adenosine Triphosphate; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002118:Calcium; D002247:Carbon Isotopes; D002845:Chromatography; D003545:Cysteine; D004586:Electrophoresis; D007461:Iodoacetates; D007700:Kinetics; D011108:Polymers; D011485:Protein Binding; D012487:Salmonidae; D013438:Sulfhydryl Compounds
chemical_list: D000081:Acetamides; D000199:Actins; D000596:Amino Acids; D002247:Carbon Isotopes; D007461:Iodoacetates; D011108:Polymers; D013438:Sulfhydryl Compounds; D000255:Adenosine Triphosphate; D003545:Cysteine; D002118:Calcium