Therapeutic proteins face short half lives in vivo. Their high costs and associated toxicity effects of increasing dosage warrant exploration of methods to increase serum half-life. These proteins can be produced with native or engineered glycosylation sites, which has been shown to be an effective means of prolonging serum half-life. Engineered E. coli represents an economical route of production. I have been able to produce, purify and test the activity of three N-acetylgalactosaminyltransferase isoform 2 in Escherichia coli and show glycosylation on peptides derived from Interleukin 29. I followed the activity of these enzymes on three candidate therapeutic proteins via lectin blotting. Data suggest the Homo sapiens orthologue of GalNAcT2 is the most efficient enzyme in the in vitro assays with all candidate therapeutic protein substrates displaying the Tn-antigen. Future research should investigate continuous assays for precise results as well as assaying native peptides as opposed to non-native ones.