RECOMBINANT HUMAN GLYCOSYLASPARAGINASE CATALYZES HYDROLYSIS OF L-ASPARAGINE

Glycosylasparaginase is a lysosomal amidase involved in the degradatio n of glycoproteins. Recombinant human glycosylasparaginase is capable of catalyzing the hydrolysis of the amino acid L-asparagine to L-aspar tic acid and ammonia. For the hydrolysis of L-asparagine the K-m is 3- 4-fold higher and V-max 1/5 of that for glycoasparagines suggesting th at the full catalytic potential of glycosylasparaginase is not used in the hydrolysis of the free amino acid. L-Asparagine competitively inh ibits the hydrolysis of aspartylglucosamine indicating that both the a mino acid and glycoasparagine are interacting with the same active sit e of the enzyme. The hydrolytic mechanism of L-asparagine and glycoasp aragines will be discussed. (C) 1997 Federation of European Biochemica l Societies.