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Arch Biochem Biophys. 2007 May 1;461(1):50-8. Epub 2007 Mar 15.

Investigation of the ligand spectrum of human sterol carrier protein 2 using a direct mass spectrometry assay.

Author information

  • 1EMBL-Hamburg, c/o DESY, Notkestrasse 85, 22603 Hamburg, Germany. stanley@embl-hamburg.de

Abstract

Sterol carrier protein 2 (SCP2) has been investigated by nearly native electrospray ionisation mass spectrometry in the presence of long chain fatty acyl CoAs (LCFA-CoAs) and carnitine derivatives of equivalent fatty acid chain length (LCFA-carnitines). Four SCP2 constructs were compared to examine the influence of the N-terminal presequence and the C-terminal peroxisomal targeting signal on ligand binding. Removal of N- or C-terminal residues did not influence ligand binding. The observation that LCFA-CoAs are high affinity ligands for SCP2 was confirmed, while LCFA-carnitines were demonstrated for the first time not to interact with SCP2. LCFA-CoAs formed non-covalent complexes with SCP2 of 2:1 and 1:1 stoichiometry, which could be dissociated by elevating the energy of the ions upon entrance to the mass spectrometer. A fluorescence-competition assay using Nile Red butyric acid confirmed the mass spectrometric observations in solution. The physiological significance of the lack of LCFA-carnitine binding by SCP2 is discussed.

PMID:
17418802
[PubMed - indexed for MEDLINE]
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