Still, there is considerable opportunity of improvement for both versions of the PASylated peptide by optimizing the expression plasmid and the production process, including high cell density fermentation under controlled feeding conditions. Apart from that, the absence of a prominent band for the co-expressed enzyme RimJ in SDS-PAGE despite approximately 50% N-terminal acetylation of Tα1-PAS also indicates room for amelioration. Optimization of the ribosome-binding site preceding the RimJ cistron or changing the order within the bicistronic operon should boost biosynthesis of the enzyme and result in increased yield of the N-terminally acetylated Tα1-PAS. Finally, the use of a high-efficiency secretory bacterial expression system such as ESETEC [45] or CORYNEX [46,47] should lead to higher product titers as previously demonstrated for other PASylated fusion proteins such as PASylated human growth hormone (hGH) [48]. The yield of functional PAS-hGH was more than 100-fold higher with the ESETEC system than in a conventional laboratory strain of E. coli, reaching several grams per liter culture.