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Determination of substrate binding energies in individual subsites of a family 18 chitinase

2010; Wiley; Volume: 584; Issue: 22 Linguagem: Inglês

10.1016/j.febslet.2010.10.017

1873-3468

Anne Line Norberg, Vigdis Karlsen, Ingunn Alne Hoell, Ingrid Bakke, Vincent G. H. Eijsink, Morten Sørlie,

Parasites and Host Interactions

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.