ABSTRACT
Hydrogen/deuterium exchange, measured by electrospray ionization with orthogonal quadrupole time-of-flight mass spectrometry (ESI-Q-TOFMS) and by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), was used as a means to probe and map differences in conformational flexibility between the ligand-free and ligand-bound forms of cellular retinol-binding protein type I. Labelled fragments were obtained by digestion of the protein with pepsin. The differences in space-resolved time courses of deuterium incorporation identified regions that exhibit a remarkably higher degree of flexibility in the apo-protein than in the holo-protein. These segments encompass residues that are thought, on the basis of structural homology of the retinol carrier with other members of the intracellular lipid-binding proteins family, to belong to the dynamic portal through which all-trans retinol can access its high-affinity, solvent-shielded, binding site.
Subject(s)
Retinol-Binding Proteins/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Amino Acid Sequence , Animals , Binding Sites , Deuterium/chemistry , Hydrogen/chemistry , In Vitro Techniques , Ligands , Models, Molecular , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/genetics , Protein Conformation , Rats , Retinol-Binding Proteins/genetics , Retinol-Binding Proteins/metabolism , Retinol-Binding Proteins, CellularABSTRACT
The authors report their finding concerning the frequency of postoperative pulmonary thromboembolism in an autopsy series of subjects who had died with 15 days of surgery. In all cases the relationship was evaluated between death and age, sex, the underlying pathology and the type of surgery.
