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3‐Fluorotyrosine as a Complementary Probe of Hemoglobin Structure and Dynamics: A 19 F‐NMR Study of Synechococcus sp. PCC 7002 GlbN
Author(s) -
Pond Matthew P.,
Wenke Belinda B.,
Preimesberger Matthew R.,
Rice Selena L.,
Lecomte Juliette T. J.
Publication year - 2012
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.201100448
Subject(s) - chemistry , heme , cyanide , crystallography , thiocyanate , ligand (biochemistry) , microsecond , resonance (particle physics) , carbon monoxide , ferrous , nuclear magnetic resonance spectroscopy , hemoglobin , protein dynamics , deprotonation , stereochemistry , molecular dynamics , computational chemistry , inorganic chemistry , enzyme , biochemistry , organic chemistry , physics , receptor , particle physics , astronomy , catalysis , ion
The hemoglobin from the cyanobacterium Synechococcus sp. PCC 7002 (GlbN) contains three tyrosines (Tyr5, Tyr22, and Tyr53), each of which undergoes a structural rearrangement when the protein binds an exogenous ligand such as cyanide. We explored the use of 3‐fluorotyrosine and 19 F‐NMR spectroscopy for the characterization of GlbN. Assignment of 19 F resonances in fluorinated GlbN (GlbN*) was achieved with individual Tyr5Phe and Tyr53Phe replacements. We observed marked variations in chemical shift and linewidth reflecting the dependence of structural and dynamic properties on oxidation state, ligation state, and covalent attachment of the heme group. The isoelectronic complexes of ferric GlbN* with cyanide and ferrous GlbN* with carbon monoxide gave contrasting spectra, the latter exhibiting heterogeneity and enhanced internal motions on a microsecond‐to‐millisecond time scale. The strength of the H‐bond network involving Tyr22 (B10) and bound cyanide was tested at high pH. 3‐Fluorotyrosine at position 22 had a p K a value at least 3 units higher than its intrinsic value, 8.5. In addition, evidence was found for long‐range communication among the tyrosine sites. These observations demonstrated the utility of the 3‐fluorotyrosine approach to gain insight in hemoglobin properties.