The effect of intra- and intermolecular disulfide bonds after peptide grafting on the properties of yeast alcohol dehydrogenase.

Hydrophilic peptides including cysteine residues were grafted on activated yeast alcohol dehydrogenase. The grafted enzyme preparation was then submitted to oxidation at various concentrations in order to favour the formation of intramolecular or intermolecular disulfide bonds. Intermolecular bonds led to enzyme inactivation. But a rigidification of the enzyme was observed with intramolecular bonds. However, thiol groups also chelated the catalytic and structural zinc atoms, leading to the corresponding enzyme inactivation and thermolability. Formation of intramolecular disulfide bridges after peptide grafting strengthens enzyme conformation and can induce enzyme stabilization, but it has to take into account the possible interference with the naturally occurring cysteine bridges.