NMR detection of multiple transitions to low-populated states in azurin.

ABSTRACT: Transitions to conformational states with very low populations were detected for the reduced blue copper protein azurin from Pseudomonas aeruginosa by applying constant relaxation time CPMG measurements to the backbone (15)N nuclei at three magnetic fields (11.7, 14.1, and 18.8 T) and three temperatures (25.7, 35.4, and 44.8 degrees C). Two exchange processes with different rate constants could be discriminated despite populations of the excited states below 1% and spatial neighborhood of the two processes. The group of (15)N nuclei involved in the faster process exhibits at 44.8 degrees C a forward rate constant of 11.7+/-2.4 s(-1) and a population of the exited state of 0.39+/-0.07%. They surround the aromatic ring of histidine 35 whose protonation state is coupled to the flipping of a n

SUBMITTER: Korzhnev DM 

PROVIDER: S-EPMC2312403 | biostudies-literature | 2003 Jan

REPOSITORIES: biostudies-literature