61: Pharmacokinetic, pharmacodynamic and immunogenicity profiles of a pegylated recombinant Erwinia chrysanthemi-derived L-asparaginase in Mice

Abstract

This chapter presents the assay, purification, and properties of asparaginase from guinea pig serum, Escherichia coli, and Serratia marcescens. The enzyme activity of L- asparaginase from guinea pig serum may be measured by the determination of ammonia or L-aspartic acid. The assay procedure is based on the direct nesslerization of ammonia. Two different assays for L-aspartic acid have been described, one based on the amount of aspartate-14C formed from 14C-labeled asparagines and the other on the change in absorption at 340 mμ after the addition of aspartate–oxaloacetate transaminase, malic dehydrogenase, and nicotinamide adenine dinucleotide phosphate (NADH). The enzyme is stable for at least six months at -20°, to repeated freezing and thawing, and to heating at 55° for 10 minutes. It is also stable to dialysis in the cold but is labile under conditions that promote surface denaturation. The same assay methods and definition of units apply to L-Asparaginase from Escherichia coli. Escherichia coli asparaginase is inhibited specifically by 5-diazo-4-oxo-L-norvaline (DONV). The inhibition can be reversed by L-asparagine.