Nitrite Reductase Activity of Sol-Gel-encapsulated Deoxyhemoglobin: INFLUENCE OF QUATERNARY AND TERTIARY STRUCTURE

Nitrite reductase activity of deoxyhemoglobin (HbA) in the red blood cell has been proposed as a non-nitric-oxide synthase source of deliverable nitric oxide (NO) within the vasculature. An essential element in this scheme is the dependence of this reaction on the quaternary/tertiary structure of Hb...

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Bibliographic Details
Published in:The Journal of biological chemistry 2006-12, Vol.281 (48), p.36874-36882
Main Authors: Roche, Camille J, Dantsker, David, Samuni, Uri, Friedman, Joel M
Format: Article
Language:English
Subjects:
Animals
Carbon Monoxide - chemistry
Entropy
Gels - chemistry
Hemoglobins - chemistry
Hemoglobins - physiology
Hydrogen-Ion Concentration
Kinetics
Nitric Oxide - chemistry
Nitrite Reductases - chemistry
Nitrite Reductases - metabolism
Protein Structure, Quaternary
Protein Structure, Tertiary
Recombination, Genetic
Spectrophotometry
Time Factors
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Summary:Nitrite reductase activity of deoxyhemoglobin (HbA) in the red blood cell has been proposed as a non-nitric-oxide synthase source of deliverable nitric oxide (NO) within the vasculature. An essential element in this scheme is the dependence of this reaction on the quaternary/tertiary structure of HbA. In the present work sol-gel encapsulation is used to trap and stabilize deoxy-HbA in either the T or R quaternary state, thus allowing for the clear-cut monitoring of nitrite reductase activity as a function of quaternary state with and without effectors. The results indicate that reaction is not only R-T-dependent but also heterotropic effector-dependent within a given quaternary state. The use of the maximum entropy method to analyze carbon monoxide (CO) recombination kinetics from fully and partially liganded sol-gel-encapsulated T-state species provides a framework for understanding effector modulation of T-state reactivity by influencing the distribution of high and low reactivity T-state conformations.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M603914200