576 Handbook of Biomedical Optics
ubiquitous proteins may not provide very informative structural
or biochemical information.
e most important uorescent cellular marker is probably
endogenous -nicotinamide-adenine dinucleotide phosphate
(NAD(P)H) (Kierdaszuk et al. 1996). NAD(P)H is an important
coenzyme associated with the cellular metabolism and the redox
state (Masters and Chance 1999). e uorescent emission spec-
tra of NAD(P)H depends on whether it is protein bound; free
NAD(P)H absorbs in the UV region at about 340 nm and uo-
resces with a maximum at 460 nm with a uorescence lifetime of
about 400 ps, while bound NAD(P)H has a blue shied emission
spectrum and a lifetime of 2 ns. More importantly, the oxidized
form of this compound ...