However, the cell can only make up for a net loss of all nucleotides by an
increase in synthesis. The oxidation of NADH or NADPH results in elevated
enzyme activity, which permits the cell to restore the initial ratio of the
nucleotides. With NADPH, oxidation increases the activity of the pentose
phosphate pathway. Such increase also occurs following the oxidation of GSH
(Reaction 8.18). Oxidation of either NADPH or GSH, therefore, may be
responsible for the apparent increase in enzymes in the pentose phosphate
pathway after repeated O 3 exposure.
ð8:18Þ
ð8:19Þ
ð8:20Þ
8.5 CARBON MONOXIDE
8.5.1 INTRODUCTION
Carbon monoxide (CO) is an odorless, colorless, and tasteless gas found in
high concentrations in the urban atmosphere. No other gaseous air pollutants
with such a toxic potential exist at such high concentrations in urban
Air Pollution – Inorganic Gases
127
[16:53 26/8/04 P:/CRC PRESS/4365 MING-HO.751 (1670)/4365-008.3d]
Ref: 4365 MING-HO YU Chap-008 Page: 127 111-134
FIGURE 8.7 Ozonization of the nicotinamide ring in NADPH.