The stability and steady-state kinetics of vanadium chloroperoxidase from the fungus Curvularia inaequalis. van Schijndel, J.W.P.M.; Barnett, P.; Roelse, J.; Vollenbroek, E.G.M.; Wever, R.

No abstract

No abstract

The reduced stimulatory potential of HDM-GA results mainly from a loss of certain Th cell epitopes, rather than impaired allergen uptake and presentation, or induction of suppressive factors. Varying frequencies of allergoid-nonreactive HDM-specific Th cells may result in differential responses of individual patients to immunotherapy.

The binding of vanadate to the novel vanadium chloroperoxidase from C inuequalis was investigated. Reconstitution experiments of apochloroperoxidase by vanadate at different pH values showed that in the pH 6-7 range an acid/base group is present which affects the binding of the vanadate. It is proposed that this group is a histidine. This hypothesis was tested by specilically modifying this residue using diethylpyrocarbonate. In the apo-enzyme 9 histidines were modified, whereas in the holo-enzyme 6 histidines were modified. Modification with diethylpyrocarbonate had no effect on the chlorinating activity of the halo-enzyme, but when the apo-enzyme was mod&d the reactivation by vanadate was strongly inhibited. We conclude that histidine in the active site of chloroperoxidase is involved in the binding of vanadate.