Analysis of productive binding modes in the human chitotriosidase.

Human chitotriosidase (HCHT) is a family 18 chitinase that is an innate part of the immune system. We have mapped preferred productive binding modes of chito-oligosaccharide substrates to HCHT and the data show that HCHT has strong binding affinity in the +3 subsite. Moreover, HCHT shows anomer-specific binding affinities in subsites +2 and +3.

Human chitotriosidase-catalyzed hydrolysis of chitosan.

Chitotriosidase (HCHT) is one of two family 18 chitinases produced by humans, the other being acidic mammalian chitinase (AMCase). The enzyme is thought to be part of the human defense mechanism against fungal parasites, but its precise role and the details of its enzymatic properties have not yet been fully unraveled. We have studied the properties of HCHT by analyzing how the enzyme acts on high-molecular weight chitosans, soluble copolymers of β-1,4-linked N-acetylglucosamine (GlcNAc, A), and glucosamine (GlcN, D).