Enzyme kinetics of hevamine, a chitinase from the rubber tree Hevea brasiliensis

The enzyme kinetics of hevamine, a chitinase from the rubber tree Hevea bra siliensis, were studied in detail with a new enzyme assay. In this assay, t he enzyme reaction products were derivatized by reductive coupling to a chr omophore, Products mere separated by HPLC and the amount of product was cal culated by peak integration, Penta-N-acetylglucosamine (penta-nag) and hexa -N-acetylglucosamine (hexa-nag) mere used as substrates, Hexa-nag was more efficiently converted than penta-nag, which is an indication that hevamine has at least six sugar binding sites in the active site. Tetra-N-acetylgluc osamine (tetra-nag) and allosamidin were tested as inhibitors. Allosamidin nas found to be a competitive inhibitor with a K-i of 3.1 mu M. Under the c onditions tested, tetra-nag did not inhibit hevamine, (C) 2000 Federation o f European Biochemical Societies. Published by Elsevier Science B.V. All ri ghts reserved.