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Guengerich FP, Yoshimoto FK. Formation and Cleavage of C-C Bonds by Enzymatic Oxidation-Reduction Reactions. Chem Rev 2018; 118:6573-6655. [PMID: 29932643 DOI: 10.1021/acs.chemrev.8b00031] [Citation(s) in RCA: 153] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Many oxidation-reduction (redox) enzymes, particularly oxygenases, have roles in reactions that make and break C-C bonds. The list includes cytochrome P450 and other heme-based monooxygenases, heme-based dioxygenases, nonheme iron mono- and dioxygenases, flavoproteins, radical S-adenosylmethionine enzymes, copper enzymes, and peroxidases. Reactions involve steroids, intermediary metabolism, secondary natural products, drugs, and industrial and agricultural chemicals. Many C-C bonds are formed via either (i) coupling of diradicals or (ii) generation of unstable products that rearrange. C-C cleavage reactions involve several themes: (i) rearrangement of unstable oxidized products produced by the enzymes, (ii) oxidation and collapse of radicals or cations via rearrangement, (iii) oxygenation to yield products that are readily hydrolyzed by other enzymes, and (iv) activation of O2 in systems in which the binding of a substrate facilitates O2 activation. Many of the enzymes involve metals, but of these, iron is clearly predominant.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States.,Department of Chemistry , University of Texas-San Antonio , San Antonio , Texas 78249-0698 , United States
| | - Francis K Yoshimoto
- Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States.,Department of Chemistry , University of Texas-San Antonio , San Antonio , Texas 78249-0698 , United States
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Gonzalez E, Johnson KM, Pallan PS, Phan TTN, Zhang W, Lei L, Wawrzak Z, Yoshimoto FK, Egli M, Guengerich FP. Inherent steroid 17α,20-lyase activity in defunct cytochrome P450 17A enzymes. J Biol Chem 2017; 293:541-556. [PMID: 29212707 DOI: 10.1074/jbc.ra117.000504] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/11/2017] [Indexed: 01/08/2023] Open
Abstract
Cytochrome P450 (P450) 17A1 catalyzes the oxidations of progesterone and pregnenolone and is the major source of androgens. The enzyme catalyzes both 17α-hydroxylation and a subsequent 17α,20-lyase reaction, and several mechanisms have been proposed for the latter step. Zebrafish P450 17A2 catalyzes only the 17α-hydroxylations. We previously reported high similarity of the crystal structures of zebrafish P450 17A1 and 17A2 and human P450 17A1. Five residues near the heme, which differed, were changed. We also crystallized this five-residue zebrafish P450 17A1 mutant, and the active site still resembled the structure in the other proteins, with some important differences. These P450 17A1 and 17A2 mutants had catalytic profiles more similar to each other than did the wildtype proteins. Docking with these structures can explain several minor products, which require multiple enzyme conformations. The 17α-hydroperoxy (OOH) derivatives of the steroids were used as oxygen surrogates. Human P450 17A1 and zebrafish P450s 17A1 and P450 17A2 readily converted these to the lyase products in the absence of other proteins or cofactors (with catalytically competent kinetics) plus hydroxylated 17α-hydroxysteroids. The 17α-OOH results indicate that a "Compound I" (FeO3+) intermediate is capable of formation and can be used to rationalize the products. We conclude that zebrafish P450 17A2 is capable of lyase activity with the 17α-OOH steroids because it can achieve an appropriate conformation for lyase catalysis in this system that is precluded in the conventional reaction.
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Affiliation(s)
- Eric Gonzalez
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Kevin M Johnson
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Pradeep S Pallan
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Thanh T N Phan
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Wei Zhang
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Li Lei
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Zdzislaw Wawrzak
- the Life Sciences Collaborative Access Team, Sector 21, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, and
| | | | - Martin Egli
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - F Peter Guengerich
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146,
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Rammouz G, Lecanu L, Papadopoulos V. Oxidative Stress-Mediated Brain Dehydroepiandrosterone (DHEA) Formation in Alzheimer's Disease Diagnosis. Front Endocrinol (Lausanne) 2011; 2:69. [PMID: 22654823 PMCID: PMC3356139 DOI: 10.3389/fendo.2011.00069] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 10/19/2011] [Indexed: 02/06/2023] Open
Abstract
Neurosteroids are steroids made by brain cells independently of peripheral steroidogenic sources. The biosynthesis of most neurosteroids is mediated by proteins and enzymes similar to those identified in the steroidogenic pathway of adrenal and gonadal cells. Dehydroepiandrosterone (DHEA) is a major neurosteroid identified in the brain. Over the years we have reported that, unlike other neurosteroids, DHEA biosynthesis in rat, bovine, and human brain is mediated by an oxidative stress-mediated mechanism, independent of the cytochrome P450 17α-hydroxylase/17,20-lyase (CYP17A1) enzyme activity found in the periphery. This alternative pathway is induced by pro-oxidant agents, such as Fe(2+) and β-amyloid peptide. Neurosteroids are involved in many aspects of brain function, and as such, are involved in various neuropathologies, including Alzheimer's disease (AD). AD is a progressive, yet irreversible neurodegenerative disease for which there are limited means for ante-mortem diagnosis. Using brain tissue specimens from control and AD patients, we provided evidence that DHEA is formed in the AD brain by the oxidative stress-mediated metabolism of an unidentified precursor, thus depleting levels of the precursor in the blood stream. We tested for the presence of this DHEA precursor in human serum using a Fe(2+)-based reaction and determined the amounts of DHEA formed. Fe(2+) treatment of the serum resulted in a dramatic increase in DHEA levels in control patients, whereas only a moderate or no increase was observed in AD patients. The DHEA variation after oxidation correlated with the patients' cognitive and mental status. In this review, we present the cumulative evidence for oxidative stress as a natural regulator of DHEA formation and the use of this concept to develop a blood-based diagnostic tool for neurodegenerative diseases linked to oxidative stress, such as AD.
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Affiliation(s)
- Georges Rammouz
- Department of Medicine, The Research Institute of the McGill University Health Centre, McGill UniversityMontreal, QC, Canada
| | - Laurent Lecanu
- Department of Medicine, The Research Institute of the McGill University Health Centre, McGill UniversityMontreal, QC, Canada
| | - Vassilios Papadopoulos
- Department of Medicine, The Research Institute of the McGill University Health Centre, McGill UniversityMontreal, QC, Canada
- Department of Biochemistry, McGill UniversityMontreal, QC, Canada
- Department of Pharmacology and Therapeutics, McGill UniversityMontreal, QC, Canada
- *Correspondence: Vassilios Papadopoulos, The Research Institute of the McGill University Health Center, Montreal General Hospital, 1650 Cedar Avenue, C10-148, Montreal, QC, Canada H3G 1A4. e-mail:
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Cascio C, Prasad VV, Lin YY, Lieberman S, Papadopoulos V. Detection of P450c17-independent pathways for dehydroepiandrosterone (DHEA) biosynthesis in brain glial tumor cells. Proc Natl Acad Sci U S A 1998; 95:2862-7. [PMID: 9501181 PMCID: PMC19660 DOI: 10.1073/pnas.95.6.2862] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Dehydroepiandrosterone (D) is biosynthesized in the brain by a pathway different from that existing in the adrenal cortex. C6 rat glioma tumor cells in culture biosynthesize both pregnenolone (P) and D. They possess the mRNA, protein, and side-chain cleavage activity of P450scc. On the other hand, P450c17 was not detected. Adding FeSO4 to C6 cells increased the synthesis of both P and D. Even in the presence of aminoglutethimide, an inhibitor of P450scc, FeSO4 increased the synthesis of both steroids, indicating that the Fe2+-sensitive process does not involve P450scc. Likewise, the FeSO4-induced formation of D was not blocked by the P450c17 inhibitor, SU-10603. These results suggest that the FeSO4-induced synthesis of D as well as of P in C6 cells may be due to the fragmentation of in situ-formed tertiary hydroperoxides. It is likely, however, that the effect of the Fe2+ is not limited to this one reaction. When exogenous P was added to C6 microsomes, along with FeSO4, the amount of D formed was greater than control values, indicating that Fe2+ facilitated the conversion of P to D. Unlike the constituents that are converted by Fe2+ to P, the precursor of D in C6 cells is not soluble in a 1:1 mixture of ether and ethylacetate. Treatment of C6 cells with KI, NaBH4, or HIO4 resulted in an increase in D synthesis. From this it seems clear that a precursor of the D produced in C6 cells is a steroid where both C-17 and C-20 are oxygenated.
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Affiliation(s)
- C Cascio
- Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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Prasad VV, Vegesna SR, Welch M, Lieberman S. Precursors of the neurosteroids. Proc Natl Acad Sci U S A 1994; 91:3220-3. [PMID: 8159728 PMCID: PMC43547 DOI: 10.1073/pnas.91.8.3220] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In addition to the neurosteroids pregnenolone and dehydroepiandrosterone, organic solvent extracts of rat brains contain related compounds that react with various reagents to yield additional amounts of these ketosteroids. Among the chemicals producing these increments are triethylamine, HCl, FeCl3, and Pb(OAc)4. Most revealing is the action of FeSO4 on these extracts. This reducing agent also converts components of the extract into the two neurosteroids, suggesting the presence of sterol hydroperoxides or peroxides in brain. The clues provided by this study indicate that the chemical nature of the steroidal constituents existing in extracts of mammalian brains remains to be determined. It is likely that their association with neurological functions will be better understood when the structures of these substances are established.
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Affiliation(s)
- V V Prasad
- Department of Obstetrics and Gynecology, St. Luke's-Roosevelt Hospital Center, New York, NY 10019
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Prasad VV, Lieberman S. Master lecture. Reconsidering some of the biosynthetic pathways leading to formation of C19-steroids. Ann N Y Acad Sci 1990; 595:1-16. [PMID: 2197965 DOI: 10.1111/j.1749-6632.1990.tb34278.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- V V Prasad
- Department of Obstetrics and Gynecology, St. Luke's-Roosevelt Institute for Health Sciences, New York, New York 10019
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Krafft AE, Winter J, Bokkenheuser VD, Hylemon PB. Cofactor requirements of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities in cell extracts of Clostridium scindens. JOURNAL OF STEROID BIOCHEMISTRY 1987; 28:49-54. [PMID: 3475510 DOI: 10.1016/0022-4731(87)90123-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Two neutral steroid-transforming activities were demonstrated in cell extracts of Clostridium scindens. Steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase were found to be inducible in cells cultured in the presence of cortisol. Both activities required manganese ions and NAD+ or NADH for activity. Cortisol, cortisone and 11-desoxycortisol were substrates as well as inducers of steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. 17 alpha-Hydroxyprogesterone was an effective inducer but did not serve as a substrate for either enzyme activity. C. scindens is the first bacterial species of the normal human intestinal flora reported to elaborate inducible steroid-17-20-desmolase and 20 alpha-hydroxysteroid dehydrogenase activities. The results of cofactor, substrate specificity and induction studies suggest that these two activities may reside in the same enzyme complex.
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Aringer L, Eneroth P, Nordström L. Side-chain cleavage of 4-cholesten-3-one, 5-cholesten-3 alpha-ol, beta-sitosterol, and related steroids in endocrine tissues from rat and man. JOURNAL OF STEROID BIOCHEMISTRY 1979; 11:1271-85. [PMID: 513749 DOI: 10.1016/0022-4731(79)90196-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Yu PH, Tan L. Synthesis and properties of two new steroid hydroperoxides: an alternative pathway for the formation of 6beta-hydroxyprogesterone. JOURNAL OF STEROID BIOCHEMISTRY 1977; 8:825-34. [PMID: 563494 DOI: 10.1016/0022-4731(77)90090-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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