- Email: [email protected]
[61] Glutathione transferases: An overview
[61]
GLUTATHIONETRANSFERASES
495
experimental system, lipid peroxidation is inhibited by certain glutathione transferases in the presence of glutathione. 42-44 Very significant differences in inhibitory activity of the isoenzymes are apparent. Also other cellular membranes appear to be protected by the glutathione peroxidase activity. 3 That the glutathione peroxidase activity of the selenoprotein as well as of the glutathione transferases operates in vivo can be concluded from liver perfusion experiments. 45-~7 In normal rats glutathione disulfide is released into bile upon infusion of both H202 and t-butyl hydroperoxide. In selenium-deficient animals only t-butyl hydroperoxide is effective (owing to the lack of the H202-specific selenoprotein). 48 Thus, it appears evident that the glutathione peroxidase activity of both types of enzyme is important in cellular defense against a wide variety of hydroperoxides. Acknowledgments Work from the author's laboratory was supported by the Swedish Cancer Society, the Swedish Council for Planning and Coordination of Research, and the Swedish Natural Science Research Council. 4~ R. F. Burk, M. J. Trumble, and R. A. Lawrence, Biochim. Biophys. Acta 618, 35 (1980). 43 R. Morgenstern, J. W. DePierre, C. Lind, C. Guthenberg, B. Mannervik, and L. Ernster, Biochem. Biophys. Res. Commun. 99, 682 (1981). 44 K. H. Tan, D. J. Meyer, and B. Ketterer, Biochem. Soc. Trans. l l , 308 (1983). 4~ H. Sies, C. Gerstenecker, H. Menzel, and L. FIoh6, FEBS Lett. 27, 171 (1972). 46 N. Oshino and B. Chance, Biochem. J. 162, 509 (1977). 47 H. Sies, R. Brigelius, and T. P. M. Akerboom, in "Functions of Glutathione: Biochemical, Physiological, Toxicological, and Clinical Aspects" (A. Larsson, S. Orrenius, A. Holmgren, and B. Mannervik, eds.), p. 51. Raven Press, New York, 1983. 48 R. F. Burk and R. A. Lawrence, in "'Functions of Glutathione in Liver and Kidney" (H. Sies and A. Wendel, eds.), p. 114. Springer-Verlag, Berlin and New York, 1978.
[61] G l u t a t h i o n e T r a n s f e r a s e s : A n O v e r v i e w B y W I L L I A M B . JAKOBY
The glutathione transferases (EC 2.5.1.18) are among the catalysts that participate in the process of detoxication,~ the means by which those compounds without nutritional value are eliminated, usually after metabolic processing. The glutathione transferases are normally present in W. B. Jakoby, ed., "Enzymatic Basis of Detoxication," Vols. 1 and 2. Academic Press, New York, 1980.
METHODS IN ENZYMOLOGY, VOL. 113
Copyright © 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
496
GLUTATHIONE
[61]
large quantities, representing about 10% of the extractable protein of rat liver 2 but can be induced to greater than 20%. 3 Most of the work has been carried out with enzymes from rat and human liver2,~6 but human erythrocytes 7 and placenta, 8 as well as sheep 9 and mouse j° liver have also been sources for homogeneous preparations. The enzymes have been found in all mammalian tissue tested as well as in insects, protozoa, algae, fungi, and bacteria. 2,4 Included in this volume [62-64], and elsewhere in this series, ~1-13 are detailed procedures for isolation of homogeneous transferases from human and rat tissues; methods for assay of the glutathione transferases have also been made available. 14:5 The large number of glutathione transferase isoenzymes that are found in each of several species has caused considerable confusion when, as with the enzymes from rat, different means of naming them were used. A consistent system of nomenclature has now been developed for the rat ~6 and may serve as a model for other species. The nomenclature system adopted, shown in the table together with the large number of synonyms used in the past, is based on the subunit composition of the transferases. Each different subunit is denoted by an Arabic numeral. The particular isoenzymes shown in the table are presented in the order of generally decreasing isoelectric points. The major outlines of the reactions catalyzed by these enzymes, whatever their source, are clear. The glutathione transferases may be considered as catalysts of all reactions in which glutathione, as the thiolate anion, can participate as a nucleophile, providing only that a compound 2 W. B. Jakoby, Adv. Enzymol. 46, 383 (1978). 3 I. M. Arias, G. Fleischner, R. Kirsch, S. Mishkin, and Z. Gatmaitan, Arch. Biochem. Biophys. 188, 287 (1978). 4 W. B. Jakoby and W. H. Habig, in "Enzymatic Basis of Detoxication" (W. B. Jakoby, ed.), Vol. 2, p. 63. Academic Press, New York, 1980. 5 B. Mannervik and H. Jansson, J. Biol. Chem. 257, 235 (1982). 6 K. Kamisaka, W. H. Habig, J. N. Ketley, I. M. Arias, and W. B. Jakoby, Eur. J. Biochem. 60, 153 (1975). 7 C. J. Marcus, W. H. Habig, and W. B. Jakoby, Arch. Biochem. Biophys. 188, 287 (1978). g C. Guthenberg and B. Mannervik, Biochim. Biophys. Acta 661, 255 (1981). 9 C. C. Reddy, J. R. Burgess, Z. Z. Gang, E. J. Massaro, and C.-P. D. Tu, Arch. Biochem. Biophys. 224, 87 (1983). 10 C.-Y. Lee, L. Johnson, R. H. Cox, J. D. McKinney, and S.-M. Lee, J. Biol. Chem. 256, 8110 (1981). N W. H. Habig and W. B. Jakoby, this series, Vol. 77, p. 218. 12 B. Mannervik and C. Guthenberg, this series, Vol. 77, p. 231. 13 p. C. Simons and D. L. VanderJagt, this series, Vol. 77, p. 235. 14 W. H. Habig and W. B. Jakoby, this series, Vol. 77, p. 298. 15 W. H. Habig, M. J. Pabst, and W. B. Jakoby, J. Biol. Chem. 249, 7130 (1974). 16 W. B. Jakoby, B. Ketterer, and B. Mannervik, Biochem. Pharmacol. 33, 2539 (1984).
[61]
GLUTATHIONETRANSFERASES
497
NOMENCLATURE OF THE RAT GLUTATHIONE TRANSFERASES Previous systems of nomenclature New nomenclature~ Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione
transferase transferase transferase transferase transferase transferase transferase transferase transferase
1-1 ( I-2 J 2-2 3-3 3-4 4-4 5-5 6-6 7-7 t-''
c
d
e
f, g, e
h
B/'
Ligandin B
B~ B2 AA A C "D" E
YaYa Y,Yc YcY~ YbtYb~ Yh~Yb2 YjY~-' --
L~ BL B., A2 AC C, --
AA A C D E
i, j, k
MT
° This systems is based entirely on the nature of the subunits, each of which are identified by an Arabic numeral. The table is adapted from W. B. Jakoby, B. Ketterer, and B. Mannervik, Biochem. Pharmacol. 33, 2539 (1984). b Both species have been referred to as ligandin and as glutathione transferase B. ' W. B. Jakoby, Adv. Enzymol. 46, (1978). d j. D. Hayes, R. C. Strange, and I. W. Percy-Robb, Biochem. J. 197, 491 (1981). e B. Ketterer, D. Beale, J. B. Taylor, and D. J. Meyer, Biochem. Soc. Trans. 11, 466 (1983). s N. M. Bass, R. E. Kirsch, S. A. Taft, I. Marks, and S. J. Saunders, Biochim. Biophys. Acta 492, 163 (1977). N. C. Scully and T. J. Mantle, Biochem. Soc. Trans. 8, 45 (1980). h B. Mannervik and H. Jennson, J. Biol. Chem. 257, 9909 (1982). i p. j. Diericks and J. O. DeBeer, Biochem. Int. 3, 565 (1981). C. Gutenberg, P. Alin, I.M.A.strand, S. Jalqin, and B. Mannervik, in "Extrahepatic Drug Metabolism and Chemical Carcinogenesis" (J. Rydstr6m, J. Montelius, and M. Bengtsson, eds.), p. 171. Elsevier, Amsterdam, 1983. k D. J. Meyer, L. G. Christodonlides, D. Nyan, B. R. Schuster, and B. Ketterer, ibid, p. 189. I1. G. C. Robertson, H. Jensson, C. Gutenberg, M. K. Tahir, B. Jernstrom, and B. Mannervik, Biochem. Biophys. Res. Comm. 127, 80 (1985). " D. J. Meyer, D. Beale, K. H. Tan, B. Coles, and B. Ketterer, FEBS Left.. in press (1985). " C. Gutenberg, H. Jensson, N. Nystr6m, E. ()sterlund, M. K. Tahir, and B. Mannervik, Biochem. J., submitted (1985).
with a sufficiently electrophilic group binds to the enzyme. 17,~8 Leaving the caveat of binding for subsequent discussion, it is obvious that the above definition is very broad. It proposes that the glutathione transferases can utilize any ligand with a sufficiently electronegative atom, whether C, S, N, or O, as the electrophile. The enzyme participates, for example, in the initial step of mercapturic acid synthesis 15 in which a thioether is formed between G S H and the carbon of a large variety of 17 j. H. Keen, W. H. Habig, and W. B. Jakoby, J. Biol. Chem. 251, 6183 (1976). ~8j. H. Keen and W. B. Jakoby, J. Biol. Chem. 253, 5654 (1978).
498
GLUTATHIONE
[61]
(1)
GSH + CH31 ~ GSCH3 + HI GSH + CI ~ _ ~
NO~.
GS ~
NO2
/
NO2 + HCI
(2)
NO2 SG
GSH +
CH=CHCOCH~ --~
CH2CHCOCH~
(3)
GSH + RCHzNO2 ~ RCH2OH + (GSNO)2 GSH> GSSG + HNO2
(4)
GSH + RSSR' ~ GSSR + R'SH
(5)
GSH + RSCH ~ RSSG + HCN
(6)
HOO
HO
GSH + CH3(CH3)C
~ CH3(CH3)C
4- GSSG + H20
(7)
electrophiles as exemplified by Reactions (1)-(3). 2,4 Sulfur is attacked in thiocyanates [Reaction (4)] to yield the appropriate mixed disulfide and HCN, 17 or, is attacked in a mixed disulfide to result in disulfide interchange [Reaction (5)]. ~8 In Reaction (6), a nitrate nitrogen of trinitroglycerol forms an S-nitration product which undergoes reaction with a second mole of GSH to form nitrous acid.J7 The transferases also act as glutathione peroxidases (cf. this volume [60]), i.e., they attacked an oxygen, as shown for cumene hydroperoxide [Reaction (7)], but differ from the selenium-containing peroxidase by their inability to utilize hydrogen peroxide/9 To this list of reactions must be added the capability of acting as isomerases as in the conversion of aS-androstene-3,17-dione to A4_ androstene-3,17-dione, 2° or of maleylacetoacetate to fumarylacetoacetate, ~8reactions in which GSH is required only in catalytic quantities. The transferases also catalyze thiolysis, e.g., with nitrophenyl acetate to form acetylCoA and the appropriate phenol. ~8 Specificity for the thiol is limited to GSH and to its/3-alanine analog/ A report that 2-propylthiouracil can replace GSH 2~ could not be confirmed. 22 ~9j. R. Prohaska and H. E. Ganther, Biochem. Biophys. Res. Commun. 71, 952 (1977). 2o A. M. Benson, P. Talalay, J. H. Keen, and W. B. Jakoby, Proc. Natl. Acad. Sci. U.S.A. 74, 158 (1977). 2~ T. Yamada and N. Kaplowitz, J. Biol. Chem. 255, 3508 (1980). zz W. H. Habig, W. B. Jakoby, C. Guthenberg, B. Mannervik, and D. L. Vander Jagt, J, Biol. Chem. 259, 7409 (1984).
[62]
GLUTATHIONETRANSFERASE
499
This variety of type reactions is intrinsic to the glutathione transferases, a group of enzymes that display a qualitatively overlapping pattern of activity even when several species of the enzyme are found in an individual animal. 2,4,23 In addition to catalysis, these enzymes serve a storage function 24 in that they act in much the same manner, and with as great a range of ligands within cells, as does albumin in the circulation. The transferases were originally described as binding proteins under the name of ligandin, 25 emphasizing the broad range of affinity that seems to include most molecules with a lipophilic aspect. Indeed, the substrates noted in Reactions 1 though 7 testify to such versatility of binding, which is equally effective for those ligands that are insufficiently reactive electrophiles and, therefore, are not substrates. 26 Also illustrated by Reactions (1) through (7) is the enormous catalytic versatility that serves as an efficient means of coping with our exposure to the products of both Nature and the chemical industry. 23 W. H. Habig, M. J. Pabst, and W. B. Jakoby, Arch. Biochem. Biophys. 175, 710 (1976). 24 A. W. Wolkoff, R. A. Weisiger, and W. B. Jakoby, Prog. Liver Dis. 6, 213 (1979). 25 G. Litwack, B. Ketterer, and I. M. Arias, Nature (London) 234, 466 (1971). 26 j. N. Ketley, W. H. Habig, and W. B. Jakoby, J. Biol. Chem. 250, 8670 (1975).
[62] G l u t a t h i o n e T r a n s f e r a s e s f r o m H u m a n
Liver
B y MARGARETA W A R H O L M , CLAES G U T H E N B E R G , CHRISTER VON BAHR, and B E N G T MANNERVIK
The glutathione transferases are a group of related enzymes that catalyze the conjugation of glutathione with a variety of hydrophobic compounds bearing an electrophilic center. J The proteins also act as intracellular binding proteins for a large number of lipophilic substances, including bilirubin, z H u m a n glutathione transferases have been purified from liver, ~6 erythrocytes, 7 placenta, 8'9 and lung. lO W. B. Jakoby and W. H. Habig, in "Enzymatic Basis of Detoxication" (W. B. Jakoby, ed.), Vol. 2, p. 63. Academic Press, New York, 1980. 2 G. J. Smith and G. Litwack, Rev. Biochem. Toxicol. 2, 1 (1980). 3 K. Kamisaka, W. H. Habig, J. N. Ketley, I. M. Arias, and W. B. Jakoby, Eur. J. Biochem. 60, 153 (1975). 4 p. C. Simons and D. L. Vander Jagt, Anal. Biochem. 82, 334 (1977). 5 y . C. Awasthi, D. D. Dao, and R. P. Saneto, Biochem. J. 191, 1 (1980). 6 M. Warholm, C. Guthenberg, B. Mannervik, and C. von Bahr, Biochem. Biophys. Res. Commun. 98, 512 (1981).
METHODS IN ENZYMOLOGY, VOL. 113
Copyright © 1985 by Academic Press, Inc. All rights of reproduction in any form reserved'.
GLUTATHIONETRANSFERASES
495
experimental system, lipid peroxidation is inhibited by certain glutathione transferases in the presence of glutathione. 42-44 Very significant differences in inhibitory activity of the isoenzymes are apparent. Also other cellular membranes appear to be protected by the glutathione peroxidase activity. 3 That the glutathione peroxidase activity of the selenoprotein as well as of the glutathione transferases operates in vivo can be concluded from liver perfusion experiments. 45-~7 In normal rats glutathione disulfide is released into bile upon infusion of both H202 and t-butyl hydroperoxide. In selenium-deficient animals only t-butyl hydroperoxide is effective (owing to the lack of the H202-specific selenoprotein). 48 Thus, it appears evident that the glutathione peroxidase activity of both types of enzyme is important in cellular defense against a wide variety of hydroperoxides. Acknowledgments Work from the author's laboratory was supported by the Swedish Cancer Society, the Swedish Council for Planning and Coordination of Research, and the Swedish Natural Science Research Council. 4~ R. F. Burk, M. J. Trumble, and R. A. Lawrence, Biochim. Biophys. Acta 618, 35 (1980). 43 R. Morgenstern, J. W. DePierre, C. Lind, C. Guthenberg, B. Mannervik, and L. Ernster, Biochem. Biophys. Res. Commun. 99, 682 (1981). 44 K. H. Tan, D. J. Meyer, and B. Ketterer, Biochem. Soc. Trans. l l , 308 (1983). 4~ H. Sies, C. Gerstenecker, H. Menzel, and L. FIoh6, FEBS Lett. 27, 171 (1972). 46 N. Oshino and B. Chance, Biochem. J. 162, 509 (1977). 47 H. Sies, R. Brigelius, and T. P. M. Akerboom, in "Functions of Glutathione: Biochemical, Physiological, Toxicological, and Clinical Aspects" (A. Larsson, S. Orrenius, A. Holmgren, and B. Mannervik, eds.), p. 51. Raven Press, New York, 1983. 48 R. F. Burk and R. A. Lawrence, in "'Functions of Glutathione in Liver and Kidney" (H. Sies and A. Wendel, eds.), p. 114. Springer-Verlag, Berlin and New York, 1978.
[61] G l u t a t h i o n e T r a n s f e r a s e s : A n O v e r v i e w B y W I L L I A M B . JAKOBY
The glutathione transferases (EC 2.5.1.18) are among the catalysts that participate in the process of detoxication,~ the means by which those compounds without nutritional value are eliminated, usually after metabolic processing. The glutathione transferases are normally present in W. B. Jakoby, ed., "Enzymatic Basis of Detoxication," Vols. 1 and 2. Academic Press, New York, 1980.
METHODS IN ENZYMOLOGY, VOL. 113
Copyright © 1985 by Academic Press, Inc. All rights of reproduction in any form reserved.
496
GLUTATHIONE
[61]
large quantities, representing about 10% of the extractable protein of rat liver 2 but can be induced to greater than 20%. 3 Most of the work has been carried out with enzymes from rat and human liver2,~6 but human erythrocytes 7 and placenta, 8 as well as sheep 9 and mouse j° liver have also been sources for homogeneous preparations. The enzymes have been found in all mammalian tissue tested as well as in insects, protozoa, algae, fungi, and bacteria. 2,4 Included in this volume [62-64], and elsewhere in this series, ~1-13 are detailed procedures for isolation of homogeneous transferases from human and rat tissues; methods for assay of the glutathione transferases have also been made available. 14:5 The large number of glutathione transferase isoenzymes that are found in each of several species has caused considerable confusion when, as with the enzymes from rat, different means of naming them were used. A consistent system of nomenclature has now been developed for the rat ~6 and may serve as a model for other species. The nomenclature system adopted, shown in the table together with the large number of synonyms used in the past, is based on the subunit composition of the transferases. Each different subunit is denoted by an Arabic numeral. The particular isoenzymes shown in the table are presented in the order of generally decreasing isoelectric points. The major outlines of the reactions catalyzed by these enzymes, whatever their source, are clear. The glutathione transferases may be considered as catalysts of all reactions in which glutathione, as the thiolate anion, can participate as a nucleophile, providing only that a compound 2 W. B. Jakoby, Adv. Enzymol. 46, 383 (1978). 3 I. M. Arias, G. Fleischner, R. Kirsch, S. Mishkin, and Z. Gatmaitan, Arch. Biochem. Biophys. 188, 287 (1978). 4 W. B. Jakoby and W. H. Habig, in "Enzymatic Basis of Detoxication" (W. B. Jakoby, ed.), Vol. 2, p. 63. Academic Press, New York, 1980. 5 B. Mannervik and H. Jansson, J. Biol. Chem. 257, 235 (1982). 6 K. Kamisaka, W. H. Habig, J. N. Ketley, I. M. Arias, and W. B. Jakoby, Eur. J. Biochem. 60, 153 (1975). 7 C. J. Marcus, W. H. Habig, and W. B. Jakoby, Arch. Biochem. Biophys. 188, 287 (1978). g C. Guthenberg and B. Mannervik, Biochim. Biophys. Acta 661, 255 (1981). 9 C. C. Reddy, J. R. Burgess, Z. Z. Gang, E. J. Massaro, and C.-P. D. Tu, Arch. Biochem. Biophys. 224, 87 (1983). 10 C.-Y. Lee, L. Johnson, R. H. Cox, J. D. McKinney, and S.-M. Lee, J. Biol. Chem. 256, 8110 (1981). N W. H. Habig and W. B. Jakoby, this series, Vol. 77, p. 218. 12 B. Mannervik and C. Guthenberg, this series, Vol. 77, p. 231. 13 p. C. Simons and D. L. VanderJagt, this series, Vol. 77, p. 235. 14 W. H. Habig and W. B. Jakoby, this series, Vol. 77, p. 298. 15 W. H. Habig, M. J. Pabst, and W. B. Jakoby, J. Biol. Chem. 249, 7130 (1974). 16 W. B. Jakoby, B. Ketterer, and B. Mannervik, Biochem. Pharmacol. 33, 2539 (1984).
[61]
GLUTATHIONETRANSFERASES
497
NOMENCLATURE OF THE RAT GLUTATHIONE TRANSFERASES Previous systems of nomenclature New nomenclature~ Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione Glutathione
transferase transferase transferase transferase transferase transferase transferase transferase transferase
1-1 ( I-2 J 2-2 3-3 3-4 4-4 5-5 6-6 7-7 t-''
c
d
e
f, g, e
h
B/'
Ligandin B
B~ B2 AA A C "D" E
YaYa Y,Yc YcY~ YbtYb~ Yh~Yb2 YjY~-' --
L~ BL B., A2 AC C, --
AA A C D E
i, j, k
MT
° This systems is based entirely on the nature of the subunits, each of which are identified by an Arabic numeral. The table is adapted from W. B. Jakoby, B. Ketterer, and B. Mannervik, Biochem. Pharmacol. 33, 2539 (1984). b Both species have been referred to as ligandin and as glutathione transferase B. ' W. B. Jakoby, Adv. Enzymol. 46, (1978). d j. D. Hayes, R. C. Strange, and I. W. Percy-Robb, Biochem. J. 197, 491 (1981). e B. Ketterer, D. Beale, J. B. Taylor, and D. J. Meyer, Biochem. Soc. Trans. 11, 466 (1983). s N. M. Bass, R. E. Kirsch, S. A. Taft, I. Marks, and S. J. Saunders, Biochim. Biophys. Acta 492, 163 (1977). N. C. Scully and T. J. Mantle, Biochem. Soc. Trans. 8, 45 (1980). h B. Mannervik and H. Jennson, J. Biol. Chem. 257, 9909 (1982). i p. j. Diericks and J. O. DeBeer, Biochem. Int. 3, 565 (1981). C. Gutenberg, P. Alin, I.M.A.strand, S. Jalqin, and B. Mannervik, in "Extrahepatic Drug Metabolism and Chemical Carcinogenesis" (J. Rydstr6m, J. Montelius, and M. Bengtsson, eds.), p. 171. Elsevier, Amsterdam, 1983. k D. J. Meyer, L. G. Christodonlides, D. Nyan, B. R. Schuster, and B. Ketterer, ibid, p. 189. I1. G. C. Robertson, H. Jensson, C. Gutenberg, M. K. Tahir, B. Jernstrom, and B. Mannervik, Biochem. Biophys. Res. Comm. 127, 80 (1985). " D. J. Meyer, D. Beale, K. H. Tan, B. Coles, and B. Ketterer, FEBS Left.. in press (1985). " C. Gutenberg, H. Jensson, N. Nystr6m, E. ()sterlund, M. K. Tahir, and B. Mannervik, Biochem. J., submitted (1985).
with a sufficiently electrophilic group binds to the enzyme. 17,~8 Leaving the caveat of binding for subsequent discussion, it is obvious that the above definition is very broad. It proposes that the glutathione transferases can utilize any ligand with a sufficiently electronegative atom, whether C, S, N, or O, as the electrophile. The enzyme participates, for example, in the initial step of mercapturic acid synthesis 15 in which a thioether is formed between G S H and the carbon of a large variety of 17 j. H. Keen, W. H. Habig, and W. B. Jakoby, J. Biol. Chem. 251, 6183 (1976). ~8j. H. Keen and W. B. Jakoby, J. Biol. Chem. 253, 5654 (1978).
498
GLUTATHIONE
[61]
(1)
GSH + CH31 ~ GSCH3 + HI GSH + CI ~ _ ~
NO~.
GS ~
NO2
/
NO2 + HCI
(2)
NO2 SG
GSH +
CH=CHCOCH~ --~
CH2CHCOCH~
(3)
GSH + RCHzNO2 ~ RCH2OH + (GSNO)2 GSH> GSSG + HNO2
(4)
GSH + RSSR' ~ GSSR + R'SH
(5)
GSH + RSCH ~ RSSG + HCN
(6)
HOO
HO
GSH + CH3(CH3)C
~ CH3(CH3)C
4- GSSG + H20
(7)
electrophiles as exemplified by Reactions (1)-(3). 2,4 Sulfur is attacked in thiocyanates [Reaction (4)] to yield the appropriate mixed disulfide and HCN, 17 or, is attacked in a mixed disulfide to result in disulfide interchange [Reaction (5)]. ~8 In Reaction (6), a nitrate nitrogen of trinitroglycerol forms an S-nitration product which undergoes reaction with a second mole of GSH to form nitrous acid.J7 The transferases also act as glutathione peroxidases (cf. this volume [60]), i.e., they attacked an oxygen, as shown for cumene hydroperoxide [Reaction (7)], but differ from the selenium-containing peroxidase by their inability to utilize hydrogen peroxide/9 To this list of reactions must be added the capability of acting as isomerases as in the conversion of aS-androstene-3,17-dione to A4_ androstene-3,17-dione, 2° or of maleylacetoacetate to fumarylacetoacetate, ~8reactions in which GSH is required only in catalytic quantities. The transferases also catalyze thiolysis, e.g., with nitrophenyl acetate to form acetylCoA and the appropriate phenol. ~8 Specificity for the thiol is limited to GSH and to its/3-alanine analog/ A report that 2-propylthiouracil can replace GSH 2~ could not be confirmed. 22 ~9j. R. Prohaska and H. E. Ganther, Biochem. Biophys. Res. Commun. 71, 952 (1977). 2o A. M. Benson, P. Talalay, J. H. Keen, and W. B. Jakoby, Proc. Natl. Acad. Sci. U.S.A. 74, 158 (1977). 2~ T. Yamada and N. Kaplowitz, J. Biol. Chem. 255, 3508 (1980). zz W. H. Habig, W. B. Jakoby, C. Guthenberg, B. Mannervik, and D. L. Vander Jagt, J, Biol. Chem. 259, 7409 (1984).
[62]
GLUTATHIONETRANSFERASE
499
This variety of type reactions is intrinsic to the glutathione transferases, a group of enzymes that display a qualitatively overlapping pattern of activity even when several species of the enzyme are found in an individual animal. 2,4,23 In addition to catalysis, these enzymes serve a storage function 24 in that they act in much the same manner, and with as great a range of ligands within cells, as does albumin in the circulation. The transferases were originally described as binding proteins under the name of ligandin, 25 emphasizing the broad range of affinity that seems to include most molecules with a lipophilic aspect. Indeed, the substrates noted in Reactions 1 though 7 testify to such versatility of binding, which is equally effective for those ligands that are insufficiently reactive electrophiles and, therefore, are not substrates. 26 Also illustrated by Reactions (1) through (7) is the enormous catalytic versatility that serves as an efficient means of coping with our exposure to the products of both Nature and the chemical industry. 23 W. H. Habig, M. J. Pabst, and W. B. Jakoby, Arch. Biochem. Biophys. 175, 710 (1976). 24 A. W. Wolkoff, R. A. Weisiger, and W. B. Jakoby, Prog. Liver Dis. 6, 213 (1979). 25 G. Litwack, B. Ketterer, and I. M. Arias, Nature (London) 234, 466 (1971). 26 j. N. Ketley, W. H. Habig, and W. B. Jakoby, J. Biol. Chem. 250, 8670 (1975).
[62] G l u t a t h i o n e T r a n s f e r a s e s f r o m H u m a n
Liver
B y MARGARETA W A R H O L M , CLAES G U T H E N B E R G , CHRISTER VON BAHR, and B E N G T MANNERVIK
The glutathione transferases are a group of related enzymes that catalyze the conjugation of glutathione with a variety of hydrophobic compounds bearing an electrophilic center. J The proteins also act as intracellular binding proteins for a large number of lipophilic substances, including bilirubin, z H u m a n glutathione transferases have been purified from liver, ~6 erythrocytes, 7 placenta, 8'9 and lung. lO W. B. Jakoby and W. H. Habig, in "Enzymatic Basis of Detoxication" (W. B. Jakoby, ed.), Vol. 2, p. 63. Academic Press, New York, 1980. 2 G. J. Smith and G. Litwack, Rev. Biochem. Toxicol. 2, 1 (1980). 3 K. Kamisaka, W. H. Habig, J. N. Ketley, I. M. Arias, and W. B. Jakoby, Eur. J. Biochem. 60, 153 (1975). 4 p. C. Simons and D. L. Vander Jagt, Anal. Biochem. 82, 334 (1977). 5 y . C. Awasthi, D. D. Dao, and R. P. Saneto, Biochem. J. 191, 1 (1980). 6 M. Warholm, C. Guthenberg, B. Mannervik, and C. von Bahr, Biochem. Biophys. Res. Commun. 98, 512 (1981).
METHODS IN ENZYMOLOGY, VOL. 113
Copyright © 1985 by Academic Press, Inc. All rights of reproduction in any form reserved'.