Involvement of cysteine residues in the electrophoretic mobility of histone H3 in acid-urea-Triton gels.

Carbamylation of cysteines 96 and 110 in histone H3 increases the electrophoretic mobility of this histone in acetic acid-urea-Triton X-100 polyacrylamide gels but has no effect in gels lacking Triton. Residue 96 appears to be a major determinant in the affinity of histone H3 for the nonionic detergent Triton. Carbamylation and carboxymethylation of cysteine 96 caused a major loss of the gel retardation caused by Triton. Carbamylation of cysteine 110 did not affect Triton binding but prevented ionization of the thiol side-chain moiety in the acetic acid-urea-Triton X-100 gel.