Paper accepted: “Hydrolysis of chitin and chitosans by the human chitinolytic enzymes: chitotriosidase, acidic mammalian chitinase, and lysozyme”

Today, another of the manuscripts which are part of Margareta Hellmann’s doctoral thesis has been accepted for publication in the International Journal of Biological Macromolecules. It also contains data from Gian Luca Morangiu’s MSc project which he did under the guidance of Margareta and their supervisor, Dr. Stefan Cord-Landwehr, and supported by our collaborator Dr. Christian Gorzelanny from the Institute for Experimental Dermatology at the University Medical Center Hamburg-Eppendorf. The paper describes a thorough analysis of the three human chitinolytic enzymes: chitotriosidase, acidic mammalian chitinase, and lysozyme. A lot has been published on these enzymes already, but this is the first direct comparison, in particular regarding their ability to hydrolyse partially acetylated and fully deacetylated chitosans, and the chitosan oligomers thus produced. The two true chitinases, chitotriosidase and acidic mammalian chitinase, turned out to be more similar in their enzymatic properties than hitherto thought, while lysozyme, whose preferred substrates are bacterial cell wall mureins, is quite different. None of the enzymes is able to degrade fully deacetylated chitosans, so that the degree and pattern of acetylation of the chitosans is crucially determining their rate of enzymatic degradation, as well as the quantity and quality of the products generated. Clearly, this is critical knowledge for the development of chitosan-based medical and pharmaceutical applications, and it will allow the design of novel chitosans which are degradable in the human body, and which lead to in situ-production of defined bioactive chitosan oligomers, while preventing the production of unwanted ones. This is also the first step of Margareta’s and Christian’s new DFG-supported and CodeΧ-associated project aiming to understand the role of chitosans in human-pathogenic fungi such as Cryptococcus neoformans.