Neuroglobin is  a hexa-coodinate globin with a neuro-protective function.  The reduction/oxidation of  the disulfide bridge between Cys46 and Cys55 in the CD loop in human neuroglobin alters  kinetics and thermodynamics of neuroglobin interactions with  exogenous diatomic ligands.  To understand the molecular mechanism of the transmission of structural changes between the CD loop and  the heme binding pocket, Tyr44 was  replaced by Phe and dynamics and energetics of structural changes associated with the CO photo-release were characterized.  Tyr 44 mutation leads to a decrease of the volume and enthalpy changes associated with the CO photo-release from reduced neuroglobin whereas no  impact was observed for oxidized protein. Together with computational results we propose that oxidation/reduction of the disulfide bridge alters  orientation of the Tyr 44 side-chain and modulates the hydrogen bonding network between heme propionate, Tyr44, His64 and Lys 67.

Role of Tyr 44 in transmitting structural information between the CD-loop and heme binding site in neuroglobin

245th National Meeting (2013)

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