. "The covalent binding of a pyrromethane (dipyrrin) cofactor to protein via the sulfur atom of cysteine forming dipyrrolylmethanemethyl-L-cysteine." . . . "peptidyl-pyrromethane cofactor linkage" . "dipyrromethane cofactor binding" . "peptidyl-pyrromethane cofactor linkage via dipyrrolylmethanemethyl-L-cysteine" . . . . .