Characterization of millisecond time-scale dynamics in the molten globule state of α-lactalbumin by NMR Academic Article uri icon

Overview

MeSH Major

  • Lactalbumin
  • Magnetic Resonance Spectroscopy

abstract

  • The motional dynamics of the molten globule (MG) state of alpha-lactalbumin have been characterized using (15)N transverse relaxation rates (R2). A modified version of the Carr-Purcell-Meiboom-Gill (CPMG) R2 pulse sequence is proposed in order to overcome the loss of sensitivity that arises from extreme line broadening due to complex dynamics on the millisecond time-scale. Using this pulse sequence, chemical exchange rates were extracted by examining the (15)N transverse relaxation rates as a function of CPMG delay values. The results clearly illustrate that pervasive conformational exchange of 0.2-0.5 ms in the (15)N backbone resonances of the molten globule state of alpha-lactalbumin. The temperature dependence of the conformational exchange rates display standard Arrhenius kinetic behavior between 10 and 30 degrees C. Estimates of the activation energies range from 0.8 to 4. 4 kcal/mol, indicating a low energetic barrier to conformational fluctuations relative to native state proteins. The fluctuations and low energetic barriers may be critical for directing the search for contacts that will result in the transition from the MG state to the native state.

publication date

  • November 26, 1999

Research

keywords

  • Academic Article

Identity

Language

  • eng

Digital Object Identifier (DOI)

  • 10.1006/jmbi.1999.3250

PubMed ID

  • 10610779

Additional Document Info

start page

  • 551

end page

  • 60

volume

  • 294

number

  • 2