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 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.
Roche
Camille J
CJ
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Dantsker
David
D
Samuni
Uri
U
Friedman
Joel M
JM
D000818:Animals; D002248:Carbon Monoxide / Q000737:chemistry; D019277:Entropy; D005782:Gels / Q000737:chemistry*; D006454:Hemoglobins / Q000737:chemistry* / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009569:Nitric Oxide / Q000737:chemistry; D009572:Nitrite Reductases / Q000737:chemistry / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D013053:Spectrophotometry; D013997:Time Factors
D005782:Gels; D006454:Hemoglobins; D009569:Nitric Oxide; D002248:Carbon Monoxide; C100003:deoxyhemoglobin; D009572:Nitrite Reductases