A fragment of staphylococcal nuclease with an OB-fold structure shows hydrogen-exchange protection factors in the range reported for "molten globules".
Hydrogen-exchange rates for an OB-fold subdomain fragment of staphylococcal nuclease have been measured at pH 4.7 and 4 degrees C, conditions close to the minimum of acid/base catalyzed exchange. The strongest protection from solvent exchange is observed for residues from a five-stranded beta-barrel in the NMR structure of the protein. Protection factors, calculated from the experimental hydrogen-exchange rates, range between 1 and 190. Similarly small protection factors have in many cases been attributed to "molten globule" conformations that are supposed to lack a specific tertiary structure. The present results suggest that marginal protection from solvent exchange does not exclude well-defined structure.
Alexandrescu
A T
AT
Department of Structural Biology, Biozentrum, University of Basel, Switzerland.
Dames
S A
SA
Wiltscheck
R
R
D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008836:Micrococcal Nuclease / Q000737:chemistry*; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013696:Temperature; D013816:Thermodynamics
D010446:Peptide Fragments; D008836:Micrococcal Nuclease