Inhibition of family 18 chitinases has several interesting applications To this regard it is important to understand the dependency of binding energetics with respect to the nature of the ligand as well as the chitinase We have studied the binding of hexameric N-acetylglucosamine (GIcNAc)6 to both glycon and aglycon subsites in chitinase B (ChiB) of Serratia marcescens and we compare the results with binding of allosamidin to ChIB (glycon subsites only, where products are released) and to chitinase A (ChiA) of S marcescens (glycon subsites only where polymeric substrates bind) The Delta G(r), values for the three binding processes were identical within experimental errors (-38 kJ/mol) while binding was driven by different factors being solvation entropy (-TAS degrees(solv) = -523 +/- 1 5 kJ/mol) conformational entropy (-TAS degrees(conf) -45 +/- 220 kJ/mol) 1271 and equal contributions of Delta H degrees(r); and -TAS degrees(solv) (-23 4 +/- 09 and -204 +/- 3 1 kJ/mol)[29] respectively (C) 2010 Elsevier B V All rights reserved