title: Evaluating protein:protein complex formation using synchrotron radiation circular dichroism spectroscopy.
abstract: Circular dichroism (CD) spectroscopy beamlines at synchrotrons produce dramatically higher light flux than conventional CD instruments. This property of synchrotron radiation circular dichroism (SRCD) results in improved signal-to-noise ratios and allows data collection to lower wavelengths, characteristics that have led to the development of novel SRCD applications. Here we describe the use of SRCD to study protein complex formation, specifically evaluating the complex formed between carboxypeptidase A and its protein inhibitor latexin. Crystal structure analyses of this complex and the individual proteins reveal only minor changes in secondary structure of either protein upon complex formation (i.e., it involves only rigid body interactions). Conventional CD spectroscopy reports on changes in secondary structure and would therefore not be expected to be sensitive to such interactions. However, in this study we have shown that SRCD can identify differences in the vacuum ultraviolet CD spectra that are significant and attributable to complex formation.
authors: Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia. n.cowieson@imb.uq.edu.au
authors: Nathan P
authors: NP
authors: Cowieson
authors: Andrew J
authors: AJ
authors: Miles
authors: Gautier
authors: G
authors: Robin
authors: Jade K
authors: JK
authors: Forwood
authors: Bostjan
authors: B
authors: Kobe
authors: Jennifer L
authors: JL
authors: Martin
authors: B A
authors: BA
authors: Wallace
mesh_terms: D000941:Antigens / Q000737:chemistry; D043422:Carboxypeptidases A / Q000037:antagonists & inhibitors / Q000737:chemistry*; D002942:Circular Dichroism / Q000295:instrumentation* / Q000379:methods; D004791:Enzyme Inhibitors / Q000737:chemistry*; D046912:Multiprotein Complexes / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017356:Synchrotrons
chemical_list: D000941:Antigens; D004791:Enzyme Inhibitors; C086812:Lxn protein, rat; D046912:Multiprotein Complexes; D043422:Carboxypeptidases A