Binding thermodynamics of ferredoxin:NADP+ reductase: two different protein substrates and one energetics.

ABSTRACT: The thermodynamics of the formation of binary and ternary complexes between Anabaena PCC 7119 FNR and its substrates, NADP+ and Fd, or Fld, has been studied by ITC. Despite structural dissimilarities, the main difference between Fd and Fld binding to FNR relates to hydrophobicity, reflected in different binding heat capacity and number of water molecules released from the interface. At pH 8, the formation of the binary complexes is both enthalpically and entropically driven, accompanied by the protonation of at least one ionizable group. His299 FNR has been identified as the main responsible for the proton exchange observed. However, at pH 10, where no protonation occurs and intrinsic binding parameters can be obtained, the formation of the binary complexes is entropically driven, with neg

SUBMITTER: Martinez-Julvez M 

PROVIDER: S-EPMC2712046 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature