The kinetic folding intermediate of ribonuclease H resembles the acid molten globule and partially unfolded molecules detected under native conditions.
Folding of ribonuclease HI from Escherichia coli populates a kinetic intermediate detectable by stopped-flow circular dichroism. Pulse labelling hydrogen exchange reveals that this intermediate consists of a structured core region of the protein, namely helices A and D and beta-strand 4. This kinetic intermediate resembles both the acid molten globule of ribonuclease HI and rarely populated, partially unfolded forms detected under native conditions. These results indicate that the first portion of ribonuclease HI to fold is the most thermodynamically stable region of the native state, and that folding of this protein follows a hierarchical process.
Raschke
T M
TM
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
Marqusee
S
S
D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000201:enzymology; D017022:Flow Injection Analysis; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D017510:Protein Folding; D016914:Ribonuclease H; D014508:Urea / Q000494:pharmacology
D014508:Urea; D016914:Ribonuclease H; C078856:ribonuclease HI