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Article ; Online: The "Origin-of-Life Reactor" and Reduction of CO

Jackson, J Baz

2017 Volume 85, Issue 1-2, Page(s) 1–7

Abstract: It has been suggested that inorganic membranes were forerunners of organic membranes at the origin of life. Such membranes, interposed between alkaline fluid in submarine vents and the more acidic Hadean ocean, were thought to house inorganic molecular ... ...

Abstract	It has been suggested that inorganic membranes were forerunners of organic membranes at the origin of life. Such membranes, interposed between alkaline fluid in submarine vents and the more acidic Hadean ocean, were thought to house inorganic molecular machines. H
Language	English
Publishing date	2017-08
Publishing country	Germany
Document type	Letter
ZDB-ID	120148-7
ISSN	1432-1432 ; 0022-2844
ISSN (online)	1432-1432
ISSN	0022-2844
DOI	10.1007/s00239-017-9805-9
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Article: Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?

Jackson, J Baz

Life (Basel, Switzerland)

2017 Volume 7, Issue 3

Abstract: We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse ... ...

Abstract	We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic chemistry. In this article, we temporarily suspend our earlier criticism while we consider difficulties for primitive organisms to have managed their energy supply and to have left the vents and become free-living. We point out that it may have been impossible for organisms to have acquired membrane-located proton (or sodium ion) pumps to replace the natural pH gradient, and independently to have driven essential molecular machines such as the ATP synthase. The volumes of the ocean and of the vent fluids were too large for a membrane-located pump to have generated a significant ion concentration gradient. Our arguments apply to three of the four concurrent models employed by the proponents of the natural pH gradient hypothesis. A fourth model is exempt from these arguments but has other intrinsic difficulties that we briefly consider. We conclude that ancient organisms utilising a natural pH gradient would have been imprisoned in the vents, unable to escape and become free-living.
Language	English
Publishing date	2017-09-15
Publishing country	Switzerland
Document type	Journal Article ; Review
ZDB-ID	2662250-6
ISSN	2075-1729
ISSN	2075-1729
DOI	10.3390/life7030036
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Article ; Online: Natural pH Gradients in Hydrothermal Alkali Vents Were Unlikely to Have Played a Role in the Origin of Life.

Jackson, J Baz

Journal of molecular evolution

2016 Volume 83, Issue 1-2, Page(s) 1–11

Abstract: The hypothesis that a natural pH gradient across inorganic membranes lying between the ocean and fluid issuing from hydrothermal alkali vents provided energy to drive chemical reactions during the origin of life has an attractive parallel with ... ...

Abstract	The hypothesis that a natural pH gradient across inorganic membranes lying between the ocean and fluid issuing from hydrothermal alkali vents provided energy to drive chemical reactions during the origin of life has an attractive parallel with chemiosmotic ATP synthesis in present-day organisms. However, arguments raised in this review suggest that such natural pH gradients are unlikely to have played a part in life's origin. There is as yet no evidence for thin inorganic membranes holding sharp pH gradients in modern hydrothermal alkali vents at Lost City near the Mid-Atlantic Ridge. Proposed models of non-protein forms of the H(+)-pyrophosphate synthase that could have functioned as a molecular machine utilizing the energy of a natural pH gradient are unsatisfactory. Some hypothetical designs of non-protein motors utilizing a natural pH gradient to drive redox reactions are plausible but complex, and such motors are deemed unlikely to have assembled by chance in prebiotic times. Small molecular motors comprising a few hundred atoms would have been unable to function in the relatively thick (>1 μm) inorganic membranes that have hitherto been used as descriptive models for the natural pH gradient hypothesis. Alternative hypotheses for the evolution of chemiosmotic systems following the emergence of error-prone gene replication and translation are more likely to be correct.
MeSH term(s)	Alkalies/chemistry ; Biological Evolution ; Carbon Dioxide/chemistry ; Hot Temperature ; Hydrogen-Ion Concentration ; Hydrothermal Vents/chemistry ; Origin of Life ; Proton-Motive Force
Chemical Substances	Alkalies ; Carbon Dioxide (142M471B3J)
Language	English
Publishing date	2016-08-17
Publishing country	Germany
Document type	Journal Article ; Review
ZDB-ID	120148-7
ISSN	1432-1432 ; 0022-2844
ISSN (online)	1432-1432
ISSN	0022-2844
DOI	10.1007/s00239-016-9756-6
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Article ; Online: Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?

J. Baz Jackson

Life, Vol 7, Iss 3, p

2017 Volume 36

Abstract	We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic chemistry. In this article, we temporarily suspend our earlier criticism while we consider difficulties for primitive organisms to have managed their energy supply and to have left the vents and become free-living. We point out that it may have been impossible for organisms to have acquired membrane-located proton (or sodium ion) pumps to replace the natural pH gradient, and independently to have driven essential molecular machines such as the ATP synthase. The volumes of the ocean and of the vent fluids were too large for a membrane-located pump to have generated a significant ion concentration gradient. Our arguments apply to three of the four concurrent models employed by the proponents of the natural pH gradient hypothesis. A fourth model is exempt from these arguments but has other intrinsic difficulties that we briefly consider. We conclude that ancient organisms utilising a natural pH gradient would have been imprisoned in the vents, unable to escape and become free-living.
Keywords	natural pH gradient ; hydrothermal vents ; chemiosmotic theory ; origin of life ; Science ; Q
Subject code	612
Language	English
Publishing date	2017-09-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: A review of the binding-change mechanism for proton-translocating transhydrogenase.

Jackson, J Baz

Biochimica et biophysica acta

2012 Volume 1817, Issue 10, Page(s) 1839–1846

Abstract: Proton-translocating transhydrogenase is found in the inner membranes of animal mitochondria, and in the cytoplasmic membranes of many bacteria. It catalyses hydride transfer from NADH to NADP(+) coupled to inward proton translocation. Evidence is ... ...

Abstract	Proton-translocating transhydrogenase is found in the inner membranes of animal mitochondria, and in the cytoplasmic membranes of many bacteria. It catalyses hydride transfer from NADH to NADP(+) coupled to inward proton translocation. Evidence is reviewed suggesting the enzyme operates by a "binding-change" mechanism. Experiments with Escherichia coli transhydrogenase indicate the enzyme is driven between "open" and "occluded" states by protonation and deprotonation reactions associated with proton translocation. In the open states NADP(+)/NADPH can rapidly associate with, or dissociate from, the enzyme, and hydride transfer is prevented. In the occluded states bound NADP(+)/NADPH cannot dissociate, and hydride transfer is allowed. Crystal structures of a complex of the nucleotide-binding components of Rhodospirillum rubrum transhydrogenase show how hydride transfer is enabled and disabled at appropriate steps in catalysis, and how release of NADP(+)/NADPH is restricted in the occluded state. Thermodynamic and kinetic studies indicate that the equilibrium constant for hydride transfer on the enzyme is elevated as a consequence of the tight binding of NADPH relative to NADP(+). The protonation site in the translocation pathway must face the outside if NADP(+) is bound, the inside if NADPH is bound. Chemical shift changes detected by NMR may show where alterations in protein conformation resulting from NADP(+) reduction are initiated. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
MeSH term(s)	Animals ; Crystallography, X-Ray ; Escherichia coli/enzymology ; Escherichia coli Proteins/chemistry ; Escherichia coli Proteins/metabolism ; Humans ; Ion Transport/physiology ; Mitochondrial Membranes/enzymology ; Mitochondrial Proteins/chemistry ; Mitochondrial Proteins/metabolism ; NADP/chemistry ; NADP/metabolism ; NADP Transhydrogenases/chemistry ; NADP Transhydrogenases/metabolism ; Protons ; Rhodospirillum rubrum/enzymology
Chemical Substances	Escherichia coli Proteins ; Mitochondrial Proteins ; Protons ; NADP (53-59-8) ; NADP Transhydrogenases (EC 1.6.1.-)
Language	English
Publishing date	2012-10
Publishing country	Netherlands
Document type	Journal Article ; Review
ZDB-ID	60-7
ISSN	1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650 ; 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
ISSN (online)	1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650
ISSN	0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
DOI	10.1016/j.bbabio.2012.04.006
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Article: Proton translocation by transhydrogenase.

Jackson, J Baz

FEBS letters

2003 Volume 555, Issue 1, Page(s) 176–177

MeSH term(s)	Models, Biological ; Models, Molecular ; NADP Transhydrogenases/chemistry ; NADP Transhydrogenases/metabolism ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Proton-Motive Force ; Rhodospirillum rubrum/enzymology
Chemical Substances	NADP Transhydrogenases (EC 1.6.1.-)
Language	English
Publishing date	2003-10-01
Publishing country	England
Document type	Letter
ZDB-ID	212746-5
ISSN	1873-3468 ; 0014-5793
ISSN (online)	1873-3468
ISSN	0014-5793
DOI	10.1016/s0014-5793(03)01123-2
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Article: Proton translocation by transhydrogenase.

Jackson, J Baz

FEBS letters

2002 Volume 545, Issue 1, Page(s) 18–24

Abstract: Transhydrogenase, in animal mitochondria and bacteria, couples hydride transfer between NADH and NADP(+) to proton translocation across a membrane. Within the protein, the redox reaction occurs at some distance from the proton translocation pathway and ... ...

Abstract	Transhydrogenase, in animal mitochondria and bacteria, couples hydride transfer between NADH and NADP(+) to proton translocation across a membrane. Within the protein, the redox reaction occurs at some distance from the proton translocation pathway and coupling is achieved through conformational changes. In an 'open' conformation of transhydrogenase, in which substrate nucleotides bind and product nucleotides dissociate, the dihydronicotinamide and nicotinamide rings are held apart to block hydride transfer; in an 'occluded' conformation, they are moved into apposition to permit the redox chemistry. In the two monomers of transhydrogenase, there is a reciprocating, out-of-phase alternation of these conformations during turnover.
MeSH term(s)	Animals ; Catalytic Domain ; Ion Transport ; Models, Molecular ; NAD/metabolism ; NADP/metabolism ; NADP Transhydrogenases/chemistry ; NADP Transhydrogenases/metabolism ; Oxidation-Reduction ; Protein Binding ; Protein Conformation ; Proton Pumps/chemistry ; Proton Pumps/metabolism ; Proton-Motive Force ; Protons
Chemical Substances	Proton Pumps ; Protons ; NAD (0U46U6E8UK) ; NADP (53-59-8) ; NADP Transhydrogenases (EC 1.6.1.-)
Language	English
Publishing date	2002-07-01
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	212746-5
ISSN	1873-3468 ; 0014-5793
ISSN (online)	1873-3468
ISSN	0014-5793
DOI	10.1016/s0014-5793(03)00388-0
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Article: Letter to the Editor: Sequence-specific resonance assignments for the NADP(H)-binding component (domain III) of proton- translocating transhydrogenase from Rhodospisrillum rubrum.

Jeeves, M / Smith, K J / Quirk, P G / Cotton, N P / Baz Jackson, J

Journal of biomolecular NMR

2010 Volume 13, Issue 3, Page(s) 305–306

Language	English
Publishing date	2010-08-11
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	1081696-3
ISSN	0925-2738
ISSN	0925-2738
DOI	10.1023/A:1008300609352
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Article ; Online: Review and Hypothesis. New insights into the reaction mechanism of transhydrogenase: Swivelling the dIII component may gate the proton channel.

Jackson, J Baz / Leung, Josephine H / Stout, Charles D / Schurig-Briccio, Lici A / Gennis, Robert B

FEBS letters

2015 Volume 589, Issue 16, Page(s) 2027–2033

Abstract: The membrane protein transhydrogenase in animal mitochondria and bacteria couples reduction of NADP⁺ by NADH to proton translocation. Recent X-ray data on Thermus thermophilus transhydrogenase indicate a significant difference in the orientations of the ... ...

Abstract	The membrane protein transhydrogenase in animal mitochondria and bacteria couples reduction of NADP⁺ by NADH to proton translocation. Recent X-ray data on Thermus thermophilus transhydrogenase indicate a significant difference in the orientations of the two dIII components of the enzyme dimer (Leung et al., 2015). The character of the orientation change, and a review of information on the kinetics and thermodynamics of transhydrogenase, indicate that dIII swivelling might assist in the control of proton gating by the redox state of bound NADP⁺/NADPH during enzyme turnover.
MeSH term(s)	Animals ; Bacterial Proteins/chemistry ; Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Biocatalysis ; Humans ; Mitochondrial Membranes/enzymology ; Models, Molecular ; Mutation ; NADP Transhydrogenases/chemistry ; NADP Transhydrogenases/genetics ; NADP Transhydrogenases/metabolism ; Protein Conformation ; Protein Subunits
Chemical Substances	Bacterial Proteins ; Protein Subunits ; NADP Transhydrogenases (EC 1.6.1.-)
Language	English
Publishing date	2015-07-22
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Review
ZDB-ID	212746-5
ISSN	1873-3468 ; 0014-5793
ISSN (online)	1873-3468
ISSN	0014-5793
DOI	10.1016/j.febslet.2015.06.027
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Article: Review and Hypothesis. New insights into the reaction mechanism of transhydrogenase: Swivelling the dIII component may gate the proton channel

Jackson, J. Baz / Josephine H. Leung / Charles D. Stout / Lici A. Schurig-Briccio / Robert B. Gennis

Federation of European Biochemical Societies FEBS letters. 2015 July 22, v. 589, no. 16

2015

Abstract: The membrane protein transhydrogenase in animal mitochondria and bacteria couples reduction of NADP+ by NADH to proton translocation. Recent X-ray data on Thermus thermophilus transhydrogenase indicate a significant difference in the orientations of the ... ...

Abstract	The membrane protein transhydrogenase in animal mitochondria and bacteria couples reduction of NADP+ by NADH to proton translocation. Recent X-ray data on Thermus thermophilus transhydrogenase indicate a significant difference in the orientations of the two dIII components of the enzyme dimer (Leung et al., 2015). The character of the orientation change, and a review of information on the kinetics and thermodynamics of transhydrogenase, indicate that dIII swivelling might assist in the control of proton gating by the redox state of bound NADP+/NADPH during enzyme turnover.
Keywords	NAD (coenzyme) ; Thermus thermophilus ; X-radiation ; animals ; bacteria ; membrane proteins ; mitochondria ; thermodynamics
Language	English
Dates of publication	2015-0722
Size	p. 2027-2033.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	212746-5
ISSN	1873-3468 ; 0014-5793
ISSN (online)	1873-3468
ISSN	0014-5793
DOI	10.1016/j.febslet.2015.06.027
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