Chemistry Reference
In-Depth Information
0.024
20 × 10
-3
15
10
0.019
5
0
0.014
0
100 200 300 400
Time (
µ
s)
0.009
0.004
-0.001
1200
1250
1300
1350
Wavelength (nm)
Figure 4.8.
Near-infrared luminescence of singlet oxygen sensitized by UV irradiation
of phenylalanine in D
2
O. The emission spectrum shows a peak at about 1270 nm. Inset:
decay of singlet oxygen phosphorescence as a function of time (in microsecond), sen-
sitized by phenylalanine. The black line is a curve fit of the decay (adapted from chin
et al. [132] with the permission of the American chemical Society).
TABLE 4.5. Quantum Yields of Singlet Oxygen Generated by Photosensitized
Aromatic Amino Acids, N-Acetyl-Amino Acids, Proteins, and Immunoglobulins
a
compound
Solvent
Φ
Δ
Phe
D
2
O
0.065 ± 0.004
Tyr
D
2
O
0.138 ± 0.007
Trp
D
2
O
0.062 ± 0.011
N-Acetyl-Phe
MecN
0.083 ± 0.02
N-Acetyl-Tyr
MecN
0.19 ± 0.05
N-Acetyl-Trp
MecN
0.11 ± 0.02
BSA
D
2
O
0.037 ± 0.008
chick ovalbumin
D
2
O
0.049 ± 0.005
Bovine Igg
D
2
O
0.043 ± 0.008
Human Igg
D
2
O
0.030 ± 0.010
Sheep Igg
D
2
O
0.036
±
0.007
a
All experiments were conducted at room temperature and excited at 266 nm. Reported values
are averages of five or more measurements.
Adapted from chin et al. [132] with the permission of the American chemical Society.
4.2.1 Reactivity
The rate constants for the reactions of
1
O
2
with biological molecules such as
sterols, lipids, DNA, RNA, proteins, ascorbic acid, Trolox, and amino acids have
been determined to estimate potential consumption of
1
O
2
by different cellular
components [13, 130, 131, 151, 159, 160]. A number of reactions of
1
O
2
with
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