9864 J. Phys. Chem. A, Vol. 107, No. 46, 2003
Zielonka et al.
+
Other Reagents. â-NADH, NAD , and KSCN were obtained
sodium hydroxide and measured with ORION 420A pH meter
(Orion Research, Inc.).
from Sigma-Aldrich. KBr, NaN3, (NH4)2S2O8, 2-propanol,
perchloric acid, and sodium hydroxide were from POCH
Kinetic analysis was done with the Levenberg-Marquardt
algorithm. The first-order rate constant values (kobs) were
evaluated from the plot of ∆A vs time. The bimolecular rate
constants were determined from the slope of the linear plot of
kobs vs solute concentration.
(
Poland).
4
.2. Pulse Radiolysis. Pulse radiolysis experiments were
carried out with a high-energy (6 MeV) 17 ns electron pulse
generated from ELU-6 linear electron accelerator. The dose
absorbed per pulse was determined with N2O saturated aqueous
•
-
solution of KSCN (0.01 M), assuming G((SCN)2 ) ) 6.0 and
Acknowledgment. This work was supported by Grant No.
4 T09A 020 24 from the Ministry of Science and Informatiza-
tion.
•
-
-1
-1
ꢀ
((SCN)2 ) ) 7600 M cm (G represents yield of radicals
per 100 eV of energy absorbed, and ꢀ is molar extinction
20
coefficient at 475 nm). The dose delivered per pulse was within
the range 5-80 Gy. Details of the pulse radiolysis system are
given elsewhere.21
The pulse radiolysis of neutral water produces three highly
reactive species, eaq (2.6), OH (2.7), and H (0.6), in addition
to the formation of less-reactive products, H2O2 (0.7), H2 (0.45),
References and Notes
(1) Stryer, L. Biochemistry; Freeman: New York, 1995.
(2) (a) Abeles, R. H.; Hutton, R. F.; Westheimer, F. H. J. Am. Chem.
•
•
Soc. 1957, 79, 712. (b) Powell, M. F.; Bruice, T. C. J. Am. Chem. Soc.
983, 105, 1014. (c) Carlson, B. W.; Miller, L. L. J. Am. Chem. Soc. 1985,
107, 479. (d) Kreevoy, M. M.; Lee, I.-S. H. J. Am. Chem. Soc. 1984, 106,
550. (e) Ostovi cˇ , D. H.; Lee, I.-S. H.; Roberts, R. M. G.; Kreevoy, M. M.
1
+
and H3O (2.6) (numbers in parentheses are the G values 100
2
22
ns after electron pulse).
J. Org. Chem. 1985, 50, 4206. (f) Kreevoy, M. M.; Ostovi cˇ , D.; Lee I.-S.
H.; Binder, D. A.; King, G. W. J. Am. Chem. Soc. 1988, 110, 524. (g) Lee,
I.-S. H.; Jeoung, E. H.; Kreevoy, M. M. J. Am. Chem. Soc. 1997, 119,
To study the reaction of NADH with Br2•-, the pulse
radiolysis was carried out in the solution of KBr so that the
OH radicals react with bromide anions to form dibromide
2
722. (h) Bunting, J. Bioorg. Chem. 1991, 19, 456. (i) Yasui, S.; Ohno, A.
•
Bioorg. Chem. 1986, 14, 70.
radical anions.15
(3) (a) Carlson, B. W.; Miller, L. L.; Neta, P.; Grodkowski, J. J. Am.
Chem. Soc. 1984, 106, 7233. (b) Moiroux, J.; Elving, P. J. J. Am. Chem.
Soc. 1980, 102, 6533. (c) Anne, A.; Hapiot, P.; Moiroux, J.; Neta, P.;
Sav e´ ant, J.-M. J. Phys. Chem. 1991, 95, 2370. (d) Anne, A.; Hapiot, P.;
Moiroux, J.; Neta, P.; Sav e´ ant, J. -M J. Am. Chem. Soc. 1992, 114, 4694.
(e) Miller, L. L.; Valentine, J. R. J. Am. Chem. Soc. 1988, 110, 3982. (f)
Powell, M. F.; Wu, J. C.; Bruice, T. C. J. Am. Chem. Soc. 1984, 106, 3850.
-
•
•
-
Br + OH f Br + OH
(6)
(7)
•
-
•-
Br + Br f Br2
(
g) Almarsson, O¨ .; Sinha, A.; Gopinath, E.; Bruice, T. C. J. Am. Chem.
The solution was saturated with N2O to convert eaq into hydroxyl
radicals.15
Soc. 1993, 115, 7093.
(4) (a) Fukuzumi, S.; Tanaka, T. In Photoinduced Electron Transfer;
Fox, M. A., Chanon, M., Eds.; Elsevier: Amsterdam, 1988; Part C, p 578.
(b) Fukuzumi, S. Bull. Chem. Soc. Jpn. 1997, 70, 1.
•
-
e + N O f OH + OH + N
(8)
aq
2
2
(5) (a) Czochralska, B.; Lindqvist, L. Chem. Phys. Lett. 1983, 101,
2
97. (b) Czochralska, B.; Bojarska, E.; Pawlicki, K.; Shugar, D. Photochem.
Pulse radiolysis of aqueous solution of NaN3 leads to the
Photobiol. 1990, 51, 401. (c) Noguchi, N.; Tachikawa, M.; Takahashi, H.
In Spectroscopy of Biological Molecules: Modern Trends; Carmona, P.,
Navarro, R., Hernanz, A., Eds.; Kluwer: Netherlands, 1997; p 161.
•
•
-
formation of N3 radicals in reaction of OH radicals with N3 .
(
6) G e¸ bicki, J.; Marcinek, A.; Adamus, J.; Paneth, P.; Rogowski, J. J.
Am. Chem. Soc. 1996, 118, 691.
7) Marcinek, A.; Adamus, J.; Huben, K.; G e¸ bicki, J.; Bartczak, T.;
Bednarek, P.; Bally, T. J. Am. Chem. Soc. 2000, 122, 437.
8) (a) Fukuzumi, S.; Inada, O.; Suenobu, T. J. Am. Chem. Soc. 2002,
N3- + OH f N + OH
•
•
-
(9)
3
(
•
+
The radical NAD was produced by the reaction of NAD with
-propanol ketyl radical formed via reactions 10 and 11.
(
2
124, 14539. (b) Fukuzumi, S.; Inada, O.; Suenobu, T. J. Am. Chem. Soc.
2
003, 125, 4808.
(
•
•
9) Marcinek, A.; Adamus, J.; Rogowski, J.; G e¸ bicki, J.; Bednarek,
P.; Bally, T. J. Phys. Chem. A 2000, 104, 718.
10) Marcinek, A.; Adamus, J.; G e¸ bicki, J.; Platz, M. S.; Bednarek, P.
J. Phys. Chem. A 2000, 104, 724.
11) (a) Land, E. J.; Swallow, A. J. Biochim. Biophys. Acta 1971, 234,
4. (b) Land, E. J.; Swallow, A. J. Biochim. Biophys. Acta 1968, 162, 327.
12) Grodkowski, J.; Neta, P.; Carlson, B. W.; Miller, L. L. J. Phys.
OH + (CH ) CHOH f (CH ) COH + H O (10)
3
2
3 2
2
(
•
•
H + (CH ) CHOH f (CH ) COH + H
(11)
3
2
3 2
2
(
3
The reduction was carried out in aqueous solutions containing
M 2-propanol saturated with N2O to convert eaq into OH
(
•
1
Chem. 1983, 87, 3135.
radicals. R-Hydroxy alkyl radicals formed in reactions 10 and
1 with 85% yield (the remaining 15% are unreactive â-hydroxy
radicals) are strongly reducing species that react with many
(13) Hore, P. J.; Volbeda, A.; Dijkstra, K.; Kaptein, R. J. Am. Chem.
Soc. 1982, 104, 6262.
1
(
14) Marcinek, A.; Zielonka, J.; G e¸ bicki, J.; Gordon, C. M.; Dunkin, I.
R. J. Phys. Chem. A 2001, 105, 9305.
15) (a) Neta, P.; Huie, R. E.; Ross, A. B. J. Phys. Chem. Ref. Data
1988, 17, 1027. (b) Wardman, P. J. Phys. Chem. Ref. Data 1989, 18, 1637.
16) (a) Br u¨ hlmann, U.; Hayon, E. J. Am. Chem. Soc. 1974, 96, 6169.
b) Neta, P.; Patterson, L. K. J. Phys. Chem. 1974, 78, 2211. (c) Kosower,
E. M.; Teuerstein, A.; Burrows, H. D.; Swallow, A. J. J. Am. Chem. Soc.
+
•
compounds via one-electron transfer (E°((CH3)2CO,H /(CH3)2 -
COH) ) -1.39 V).15 This reduction method was also used in
the determination of the pKa of enol forms of radical cations,
assuming that yield of generated radicals does not change within
the pH range used.
(
(
(
1978, 100, 5185.
•
To study the reactivity of NAD radical toward oxygen, the
(17) Bielski, B. H. J.; Chan, P. C. J. Am. Chem. Soc. 1980, 102, 1713.
(18) Willson, R. L. Chem. Commun. 1970, 1005.
(19) (a) Almarsson, O¨ .; Bruice, T. C. J. Am. Chem. Soc. 1993, 115,
125. (b) Olson, L. P.; Bruice, T. C. Biochemistry 1995, 34, 7335.
radiolysis was carried out in the aerated or oxygenated solutions
+
of NAD containing HCOONa. The reducing agents in this case
2
•
-
•-
are eaq (E°(aq/eaq) ) -2.87 V) and CO2 (E°(CO2/CO2 ) )
1.9 V).15
(20) Schuler, R. H.; Patterson, L. K.; Janata, E. J. Phys. Chem. 1980,
-
84, 2088.
(21) (a) Karolczak, S.; Hodyr, K.; Łubis, R.; Kroh, J. J. Radioanal. Nucl.
-
•
•-
Chem. 1986, 101, 177. (b) Karolczak, S.; Hodyr, K.; Połowi n´ ski, M. Radiat.
Phys. Chem. 1992, 39, 1.
HCOO + OH f CO + H O
(12)
2
2
(
22) Buxton, G. V.; Greenstock, C. L.; Helman, W. P.; Ross, A. B. J.
The pH of the solutions was adjusted with perchloric acid or
Phys. Chem. Ref. Data 1988, 17, 513.