Aa. Rostom et al., DISSECTION OF MULTI-PROTEIN COMPLEXES USING MASS-SPECTROMETRY - SUBUNIT INTERACTIONS IN TRANSTHYRETIN AND RETINOL-BINDING PROTEIN COMPLEXES, Proteins, 1998, pp. 3-11
Complexes formed between transthyretin and retinol-binding protein pre
vent loss of retinol from the body through glomerular filtration. The
interactions between these proteins have been examined by electrospray
ionization combined with time-of-flight mass analysis. Conditions wer
e found whereby complexes of these proteins, containing from four to s
ix protein molecules with up to two ligands, are preserved in the gas
phase, Analysis of the mass spectra of these multimeric species gives
the overall stoichiometry of the protein subunits and provides estimat
es for solution dissociation constants of 1.9 +/- 1.0 x 10(-7) M for t
he first and 3.5 +/- 1.0 x 10(-5) M for the second retinol-binding pro
tein molecule bound to a transthyretin tetramer, Dissociation of these
protein assemblies within the gas phase of the mass spectrometer show
s that each retinol-binding protein molecule interacts with three tran
sthyretin molecules. Mass spectral analysis illustrates not only a cor
relation with solution behavior and crystallographic data of a closely
related protein complex but also exemplifies a general method for ana
lysis of multi-protein assemblies. Proteins Suppl. 2:3-11, 1998. (C) 1
998 Wiley-Liss, Inc.