A kinetic study of complexes of tryptophan and lysozyme with tetracyanoethylene

The rates of complex formation of free tryptophan and hen egg-white lysozyme with tetracyanoethylene have been investigated at different molar ratios. The reaction rates were studied by the "stopped-flow" method. The complex forming reactions follow a first order kinetics. A linear relationship of kobs. with donor concentration was found. This shows that the complex with a composition of 1:1 is predominant independently of the molar ratio between donor and acceptor. The rate of complex formation of free tryptophan and tetracyanoethylene was compared with the rate of complex formation between tetracyanoethylene and tryptophanyl residues in the lysozyme molecule. The kinetic data showed that the process of complex formation with tryptophanyl residues is slow.