Kinetics of nitric oxide binding to R-state hemoglobin.
Despite earlier work indicating otherwise, some recent reports have suggested that nitric oxide (NO) binds to hemoglobin cooperatively. In particular, it has been suggested that, under physiological conditions, NO binds to the high-affinity R-state hemoglobin as much as 100 times faster than to the low-affinity T-state hemoglobin. This rapid NO binding could provide a means of preserving NO bioactivity. However, using a flash-flow photolysis technique, we have determined that the rate of NO binding to normal adult R-state hemoglobin is (2.1 +/- 0.1) x 10(7) (s(-1) M(-1)), which is essentially the same as that reported for T-state NO binding. (c)2002 Elsevier Science (USA).
Huang
Zhi
Z
Department of Physics, Wake Forest University, Winston-Salem, North Carolina 27109, USA.
Ucer
K B
KB
Murphy
Timothy
T
Williams
Richard T
RT
King
S Bruce
SB
Kim-Shapiro
Daniel B
DB
D000494:Allosteric Regulation; D002248:Carbon Monoxide / Q000737:chemistry; D002263:Carboxyhemoglobin / Q000737:chemistry / Q000528:radiation effects; D006454:Hemoglobins / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D009569:Nitric Oxide / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010782:Photolysis / Q000528:radiation effects; D011485:Protein Binding; D013057:Spectrum Analysis
D006454:Hemoglobins; D009569:Nitric Oxide; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin; D009584:Nitrogen