Paper accepted: “Robust enzymatic-mass spectrometric fingerprinting analysis of the fraction of acetylation of chitosans”

Finally, another paper of Dr. Jasper Wattjes and Dr. Anna Niehues has been accepted for publication in the renowned international journal Carbohydrate Polymers. In this paper, we describe an improved and more robust method for the determination of the degree of acetylation of chitosan polymers by enzymatic digestion using a combination of two recombinant enzymes, a chitinase and a chitosanase, followed by quantitative mass spectrometric analysis of the small oligomeric products. Unlike the method we published previously, which was based on the digestion using chitinosanase followed by mass spectrometric quantification and statistical analysis using principal component analysis, the new method is independent on the method used in production of the chitosan sample. The old method had been developed for homogeneously N-acetylated chitosans produced in the lab, but we later found that it failed to give reasonable results with commercial chitosans produced using heterogeneous de-acetylation. This is no longer the case with the new method which is, thus, much more broadly applicable. Also, it does not rely on the rare chitinosanase which is available in our lab only, but it can be performed with any reasonably well characterized chitinase and chitosanase, and such enzymes are commercially available. What sets both the old and the new method apart from the current gold standard for the analysis of the degree of acetylation, namely NMR, is their sensitivity: where NMR requires multiple milligrams of sample, the enzymatic- mass spectrometric methods require only micrograms. But of course: Anna and Jasper developed this method not for the sake of the method development, but for the analysis of their enzymatically modified chitosans. So do look out for their next paper!