Local structure involving histidine-12 in reduced S-sulfonated ribonuclease A detected by proton NMR spectroscopy under folding conditions.
AUTOR(ES)
Swadesh, J K
RESUMO
The C epsilon H proton resonance of His-12 of reduced cysteine S-sulfonated bovine pancreatic ribonuclease A exhibits a nonlinear temperature dependence of the chemical shift in its 1H-NMR spectrum at an apparent pH of 3.0. At temperatures below ca. 35 degrees C, the temperature dependence of the chemical shift of the His-12 C epsilon H resonance is opposite in sign to those of His-48, His-105, and His-119. At temperatures above ca. 35 degrees C, the temperature dependence of the chemical shift of the His-12 C epsilon H resonance is similar to those of the other three His C epsilon H resonances. These data indicate the existence of an equilibrium between locally ordered and locally disordered environments of His-12 in the sulfonated protein at temperatures below ca. 35 degrees C. The ordered and disordered conformations interconvert at a rate that is fast relative to the 1H-NMR chemical shift time scale--i.e., the locally ordered structure has a lifetime of much less than 7 msec. These results demonstrate that short- and medium-range interactions can define short-lived local structures under conditions of temperature and solution composition at which the native protein structure is stable. Furthermore, they demonstrate the utility of reduced derivatives of disulfide-containing proteins as model systems for the identification of local structures that may play a role as early-forming chain-folding initiation structures.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=345642Documentos Relacionados
- Protective effects of S-sulfonated human gamma globulin against experimental infections in mice.
- Proton motive force in growing Streptococcus lactis and Staphylococcus aureus cells under aerobic and anaerobic conditions.
- Short-Time Fixation of Labelled Carbon Dioxide by Barley Leaves under Steady State Conditions. 12
- Staphylococcal nuclease folding intermediate characterized by hydrogen exchange and NMR spectroscopy.
- Toxin production by Clostridium botulinum type A under various fermentation conditions.