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Cavities and packing defects in the structural dynamics of myoglobin
Author(s) -
Brunori Maurizio,
Gibson Quentin H
Publication year - 2001
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1093/embo-reports/kve159
Subject(s) - myoglobin , heme , ligand (biochemistry) , active site , chemistry , docking (animal) , crystallography , molecular dynamics , biophysics , protein structure , stereochemistry , computational chemistry , biochemistry , enzyme , biology , receptor , medicine , nursing
Small globular proteins contain internal cavities and packing defects that reduce thermodynamic stability but seem to play a role in controlling function by defining pathways for the diffusion of the ligand/substrate to the active site. In the case of myoglobin (Mb), a prototype for structure–function relationship studies, the photosensitivity of the adduct of the reduced protein with CO, O 2 and NO allows events related to the migration of the ligand through the matrix to be followed. The crystal structures of intermediate states of wild‐type (wt) and mutant Mbs show the photolysed CO to be located either in the distal heme pocket (primary docking site) or in one of two alternative cavities (secondary docking sites) corresponding to packing defects accessible to an atom of xenon. These results convey the general picture that pre‐existing internal cavities are involved in controlling the dynamics and reactivity of the reactions of Mb with O 2 and other ligands, including NO.