Effects of protein-pheromone complexation on correlated chemical shift modulations

J Biomol NMR. 2005 Dec;33(4):233-42. doi: 10.1007/s10858-005-3355-y.

Abstract

Major urinary protein (MUP) is a pheromone-carrying protein of the lipocalin family. Previous studies by isothermal titration calorimetry (ITC) show that the affinity of MUP for the pheromone 2-methoxy-3-isobutylpyrazine (IBMP) is mainly driven by enthalpy, with a small unfavourable entropic contribution. Entropic terms can be attributed in part to changes in internal motions of the protein upon binding. Slow internal motions can lead to correlated or anti-correlated modulations of the isotropic chemical shifts of carbonyl C' and amide N nuclei. Correlated chemical shift modulations (CSM/CSM) in MUP have been determined by measuring differences of the transverse relaxation rates of zero- and double-quantum coherences ZQC{C'N} and DQC{C'N}, and by accounting for the effects of correlated fluctuations of dipole-dipole couplings (DD/DD) and chemical shift anisotropies (CSA/CSA). The latter can be predicted from tensor parameters of C' and N nuclei that have been determined in earlier work. The effects of complexation on slow time-scale protein dynamics can be determined by comparing the temperature dependence of the relaxation rates of APO-MUP (i.e., without ligand) and HOLO-MUP (i.e., with IBMP as a ligand).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids
  • Crystallography, X-Ray
  • Ligands
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Pheromones / chemistry*
  • Protein Binding
  • Protein Conformation
  • Proteins / chemistry*
  • Temperature

Substances

  • Amino Acids
  • Ligands
  • Pheromones
  • Proteins
  • major urinary proteins