Determination of substrate binding energies in individual subsites of a family 18 chitinase.
Thermodynamic parameters for binding of N-acetylglucosamine (GlcNAc) oligomers to a family 18 chitinase, ChiB of Serratia marcescens, have been determined using isothermal titration calorimetry. Binding studies with oligomers of different lengths showed that binding to subsites -2 and +1 is driven by a favorable enthalpy change, while binding to the two other most important subsites, +2 and +3, is driven by entropy with unfavorable enthalpy. These remarkable unfavorable enthalpy changes are most likely due to favorable enzyme-substrate interactions being offset by unfavorable enthalpic effects of the conformational changes that accompany substrate-binding.
Department of Chemistry, Biotechnology, and Food Science, The Norwegian University of Life Sciences, 1432 Ås, Norway.
Anne Line
AL
Norberg
Vigdis
V
Karlsen
Ingunn Alne
IA
Hoell
Ingrid
I
Bakke
Vincent G H
VG
Eijsink
Morten
M
Sørlie
D000117:Acetylglucosamine / Q000737:chemistry / Q000378:metabolism; D002151:Calorimetry; D002688:Chitinases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D012706:Serratia marcescens; D013816:Thermodynamics
C482346:ChiB protein, Serratia marcescens; D002688:Chitinases; D000117:Acetylglucosamine