Internal water and microsecond dynamics in myoglobin.

ABSTRACT: Myoglobin (Mb) binds diatomic ligands, like O2, CO, and NO, in a cavity that is only transiently accessible. Crystallography and molecular simulations show that the ligands can migrate through an extensive network of transiently connected cavities but disagree on the locations and occupancy of internal hydration sites. Here, we use water (2)H and (17)O magnetic relaxation dispersion (MRD) to characterize the internal water molecules in Mb under physiological conditions. We find that equine carbonmonoxy Mb contains 4.5 ± 1.0 ordered internal water molecules with a mean survival time of 5.6 ± 0.5 μs at 25 °C. The likely locations of these water molecules are the four polar hydration sites, including one of the xenon-binding cavities, that are fully occupied in all high-resolution crystal str

SUBMITTER: Kaieda S 

PROVIDER: S-EPMC3966298 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature