Modification of yeast uricase with polyethylene glycol: disappearance of binding ability towards anti-uricase serum

Uricase from Candida utilis was modified with activated polyethylene glycol (2-O-methoxypolyethylene glycol-4,6-dichloro-s-triazine) of molecular weight of 5,000 daltons. The modification of 43% of the total amino groups in the uricase molecule gave rise to a complete loss of the binding ability towards anti-uricase serum from rabbit. This modified uricase retained 15% of the enzymic activity of non-modified uricase.