4.2.2.20	additional information	when expressed in a mammalian cell, residues N675, N515, N345, N338 and N282 are all glycosylated which prevents secretion of functional enzyme. Directed mutagenesis of selected N-glycosylation sites allows efficient secretion of active chondroitinase. Mutation if residue N751 renders the enzyme inactive. Mutations required for efficient secretion of active enzyme are those eliminating glycosylation at N282, N336, N345, and N515, and mutation of N675 increases the activity still further	715688