Cysteine-directed PEGylation followed by size exclusion chromatography.

<p>(A) Mutant L-asparaginase (A38C-T263C) reduced with TCEP and eluted from the gel filtration column. Fractions 8–13 ml were pooled and used for the PEGylation crosslinking reaction. (B) 5kDa-PEG-Conjugate after crosslinking reaction, reduced with TCEP and eluted from the gel filtration column. The continuous curve represents the relative absorbance at 280 nm and the bars are the relative asparaginase catalytic activity of the fractions.