Acid-induced denaturation of Escherichia coli ribonuclease HI analyzed by CD and NMR
 

Acid-induced denaturation of Escherichia coli ribonuclease HI analyzed by CD and NMR spectroscopies.

Related Articles Acid-induced denaturation of Escherichia coli ribonuclease HI analyzed by CD and NMR spectroscopies.

Biopolymers. 2003 Jun;69(2):176-88

Authors: Yamasaki K, Yamasaki T, Kanaya S, Oobatake M

Acid-induced denaturation of the ribonuclease HI protein from Escherichia coli was analyzed by CD and NMR spectroscopies. The CD measurement revealed that the acid denaturation at 10 degrees C proceeds from the native state (N-state) to a molten globule-like state (A-state), through an apparently more unfolded state (U(A)-state). In (1)H-(15)N heteronuclear single-quantum coherence (HSQC) spectra, cross peaks from the N-state and those from the other two states are distinctively observed, while the U(A)-state and A-state are not distinguished from each other. Cross peaks from the U(A)/A-states showed a small pH dependence, which suggests a similarity in the backbone structure between the two states. The direct hydrogen-deuterium (H-D) exchange measurement at pH with the largest population of U(A)-state revealed that at least alpha-helix I is highly protected in the structure of the U(A)-state. A pH-jump H-D exchange analysis showed that the protection of alpha-helix I is highest also in the A-state. The profile of hydrogen-bond protection indicated that the structure of the A-state is closely related to that of the kinetic folding intermediate.

PMID: 12767121 [PubMed - indexed for MEDLINE]



Source: PubMed