In order to investigate the nature of actin-TM interaction by chemical modification, we constructed, as an initial step, a series of mutants that 276QT277 residues were individually substituted into a single cysteine residue by site-directed mutagenes...
In order to investigate the nature of actin-TM interaction by chemical modification, we constructed, as an initial step, a series of mutants that 276QT277 residues were individually substituted into a single cysteine residue by site-directed mutagenesis. Mutant TM22(^276CT^277), TM23(^276CA^277), and TM24(^276QC^277) were overexpressed in E. coli. were purified to near homogeneity. Actin affinities of these mutant tropomyosins were estimated 0.43× 10 exp (6)M^-1 for TM19(QA), 056× 10 exp (6)M^-1 for TM22(CT), 034× 10 exp (6)M^-1 for TM23(CA), and 023× 10 exp (6)M^-1 for TM24(QC), respectively. Since TM22(CT) bound strongest to actin among them, a cysteine residue at 276 of TM22(CT) may be an ideal target for chemical modification studies for understanding interaction of tropomyosin with actin.