title: Real-time protein NMR spectroscopy and investigation of assisted protein folding.
abstract: BACKGROUND
  During protein-folding reactions toward the native structure, short-lived intermediate states can be populated. Such intermediates expose hydrophobic patches and can self-associate leading to non-productive protein misfolding. A major focus of current research is the characterization of short-lived intermediates and how molecular chaperones enable productive folding. Real-time NMR spectroscopy, together with the development of advanced methods, is reviewed here and the potential these methods have to characterize intermediate states as well as interactions with molecular chaperone proteins at single-residue resolution is highlighted.
  
  
  METHODS
  Various chaperone interactions can guide the protein-folding reaction and thus are important for protein structure formation, stability, and activity of their substrates. Chaperone-assisted protein folding, characterization of intermediates, and their molecular interactions using real-time NMR spectroscopy will be discussed. Additionally, recent advances in NMR methods employed for characterization of high-energy intermediates will be discussed.
  
  
  CONCLUSIONS
  Real-time NMR combines high resolution with kinetic information of protein reactions, which can be employed not only for protein-folding studies and the characterization of folding intermediates but also to investigate the molecular mechanisms of assisted protein folding.
  
  
  CONCLUSIONS
  Real-time NMR spectroscopy remains an effective tool to reveal structural details about the interaction between chaperones and transient intermediates. Methodologically, it provides in-depth understanding of how kinetic intermediates and their thermodynamics contribute to the protein-folding reaction. This review summarizes the most recent advances in this field. This article is part of a Special Issue titled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
authors.affiliation: Institut für Physik, Biophysik, und Mitteldeutsches Zentrum für Struktur und Dynamik der Proteine (MZP), Martin-Luther Universität Halle-Wittenberg, Halle D-06120, Germany.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Institut für Physik, Biophysik, und Mitteldeutsches Zentrum für Struktur und Dynamik der Proteine (MZP), Martin-Luther Universität Halle-Wittenberg, Halle D-06120, Germany. Electronic address: jochen.balbach@physik.uni-halle.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Balbach
mesh_terms: D000818:Animals; D006801:Humans; D018832:Molecular Chaperones / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D017510:Protein Folding; D013816:Thermodynamics
chemical_list: D018832:Molecular Chaperones
keywords: Kinetic intermediates; Molecular chaperones; Protein folding; Real-time NMR