---
_id: '1952'
abstract:
- lang: eng
text: Two strains of Rhodospirillum rubrum were constructed in which, by a gene
dosage effect, the transhydrogenase activity of isolated chromatophores was increased
7-10-fold and 15-20-fold, respectively. The H+/H- ratio (the ratio of protons
translocated per hydride ion equivalent transferred from NADPH to an NAD+ analogue,
acetyl pyridine adenine dinucleotide), determined by a spectroscopic technique,
was approximately 1.0 for chromatophores from the over-expressing strains, but
was only approximately 0.6 for wild-type chromatophores. Highly-coupled proteoliposomes
were prepared containing purified transhydrogenase from beef-heart mitochondria.
Using the same technique, the H+/H- ratio was close to 1.0 for these proteoliposomes.
It is suggested that the mechanistic H+/H- ratio is indeed unity, but that a low
ratio is obtained in wild-type chromatophores because of inhomogeneity in the
vesicle population.
acknowledgement: L.A.S. would like to thank the Wellcome Trust, and T.B., the Biotechnology
and Biological Sciences Research Council, for financial support. We are very grateful
to Nick Cotton for helpful advice.
article_processing_charge: No
article_type: original
author:
- first_name: Tania
full_name: Bizouarn, Tania
last_name: Bizouarn
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
- first_name: Sébastien
full_name: Aubourg, Sébastien
last_name: Aubourg
- first_name: Julie
full_name: Jackson, Julie
last_name: Jackson
citation:
ama: Bizouarn T, Sazanov LA, Aubourg S, Jackson J. Estimation of the H+/H- ratio
of the reaction catalysed by the nicotinamide nucleotide transhydrogenase in chromatophores
from over-expressing strains of Rhodospirillum rubrum and in liposomes inlaid
with the purified bovine enzyme. Biochimica et Biophysica Acta - Bioenergetics.
1996;1273(1):4-12. doi:10.1016/0005-2728(95)00125-5
apa: Bizouarn, T., Sazanov, L. A., Aubourg, S., & Jackson, J. (1996). Estimation
of the H+/H- ratio of the reaction catalysed by the nicotinamide nucleotide transhydrogenase
in chromatophores from over-expressing strains of Rhodospirillum rubrum and in
liposomes inlaid with the purified bovine enzyme. Biochimica et Biophysica
Acta - Bioenergetics. Elsevier. https://doi.org/10.1016/0005-2728(95)00125-5
chicago: Bizouarn, Tania, Leonid A Sazanov, Sébastien Aubourg, and Julie Jackson.
“Estimation of the H+/H- Ratio of the Reaction Catalysed by the Nicotinamide Nucleotide
Transhydrogenase in Chromatophores from over-Expressing Strains of Rhodospirillum
Rubrum and in Liposomes Inlaid with the Purified Bovine Enzyme.” Biochimica
et Biophysica Acta - Bioenergetics. Elsevier, 1996. https://doi.org/10.1016/0005-2728(95)00125-5.
ieee: T. Bizouarn, L. A. Sazanov, S. Aubourg, and J. Jackson, “Estimation of the
H+/H- ratio of the reaction catalysed by the nicotinamide nucleotide transhydrogenase
in chromatophores from over-expressing strains of Rhodospirillum rubrum and in
liposomes inlaid with the purified bovine enzyme,” Biochimica et Biophysica
Acta - Bioenergetics, vol. 1273, no. 1. Elsevier, pp. 4–12, 1996.
ista: Bizouarn T, Sazanov LA, Aubourg S, Jackson J. 1996. Estimation of the H+/H-
ratio of the reaction catalysed by the nicotinamide nucleotide transhydrogenase
in chromatophores from over-expressing strains of Rhodospirillum rubrum and in
liposomes inlaid with the purified bovine enzyme. Biochimica et Biophysica Acta
- Bioenergetics. 1273(1), 4–12.
mla: Bizouarn, Tania, et al. “Estimation of the H+/H- Ratio of the Reaction Catalysed
by the Nicotinamide Nucleotide Transhydrogenase in Chromatophores from over-Expressing
Strains of Rhodospirillum Rubrum and in Liposomes Inlaid with the Purified Bovine
Enzyme.” Biochimica et Biophysica Acta - Bioenergetics, vol. 1273, no.
1, Elsevier, 1996, pp. 4–12, doi:10.1016/0005-2728(95)00125-5.
short: T. Bizouarn, L.A. Sazanov, S. Aubourg, J. Jackson, Biochimica et Biophysica
Acta - Bioenergetics 1273 (1996) 4–12.
date_created: 2018-12-11T11:54:53Z
date_published: 1996-01-11T00:00:00Z
date_updated: 2022-08-16T12:35:22Z
day: '11'
doi: 10.1016/0005-2728(95)00125-5
extern: '1'
external_id:
pmid:
- '8573594 '
intvolume: ' 1273'
issue: '1'
language:
- iso: eng
month: '01'
oa_version: None
page: 4 - 12
pmid: 1
publication: Biochimica et Biophysica Acta - Bioenergetics
publication_identifier:
issn:
- 0005-2728
publication_status: published
publisher: Elsevier
publist_id: '5132'
quality_controlled: '1'
status: public
title: Estimation of the H+/H- ratio of the reaction catalysed by the nicotinamide
nucleotide transhydrogenase in chromatophores from over-expressing strains of Rhodospirillum
rubrum and in liposomes inlaid with the purified bovine enzyme
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 1273
year: '1996'
...
---
_id: '1943'
abstract:
- lang: eng
text: Transhydrogenase from beef-heart mitochondria was solubilised with Triton
X-100 and purified by column chromatography. The detergent-dispersed enzyme catalysed
the reduction of acetylpyridine adenine dinucleotide (AcPdAD+) by NADH, but only
in the presence of NADP+. Experiments showed that this reaction was cyclic; NADP(H),
whilst remaining bound to the enzyme, was alternately reduced by NADH and oxidised
by AcPdAD+. A period of incubation of the enzyme with NADPH at pH 6.0 led to inhibition
of the simple transhydrogenation reaction between AcPdAD+ and NADPH. However,
after such treatment, transhydrogenase acquired the ability to catalyse the (NADPH-dependent)
reduction of AcPdAD+ by NADH. It is suggested that this is a similar cycle to
the one described above. Evidently, the binding affinity for NADP+ increases as
a consequence of the inhibition process resulting from prolonged incubation with
NADPH. The pH dependences of simple and cyclic transhydrogenation reactions are
described. Though more complex than those in Escherichia coli transhydrogenase,
they are consistent with the view [Hutton, M., Day, J.M., Bizouarn, T. and Jackson,
J.B. (1994) Eur. J. Biochem. 219, 1041–10511] that, also in the mitochondrial
enzyme, binding the release of NADP+ and NADP are accompanied by binding and release
of a proton. The enzyme was successfully reconstituted into liposomes by a cholate
dilution procedure. The proteoliposomes catalysed cyclic NADPH-dependent reduction
of AcPdAD+ by NADH only when they were tightly coupled. However, they catalysed
cyclic NADP+-dependent reduction of AcPdAD+ by NADH only when they were uncoupled
eg. by addition of carbonylcyanide-p-trifluoromethoxyphenyl hydrazone. These observations
are evidence that the proton binding and release which accompany NADP+ binding
and release, respectively, take place on the inside of the vesicle, and that they
are components of the electrogenic processes of the enzyme.
acknowledgement: 'L.A.S. is grateful to the Wellcome Trust for a Research Fellowship.
Support from the Biotechnology and Biological Sciences Research Council is also
acknowledged. We thank our colleagues. Tania Bizouarn, Mike Hutton and Nick Cotton,
for advice and valuable discussion. '
article_processing_charge: No
article_type: original
author:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
- first_name: Baz
full_name: Jackson, Baz
last_name: Jackson
citation:
ama: Sazanov LA, Jackson B. Cyclic reactions catalysed by detergent-dispersed and
reconstituted transhydrogenase from beef heart mitochondria; implications for
the mechanism of proton translocation. Biochimica et Biophysica Acta - Bioenergetics.
1995;1231(3):304-312. doi:10.1016/0005-2728(95)00096-2
apa: Sazanov, L. A., & Jackson, B. (1995). Cyclic reactions catalysed by detergent-dispersed
and reconstituted transhydrogenase from beef heart mitochondria; implications
for the mechanism of proton translocation. Biochimica et Biophysica Acta -
Bioenergetics. Elsevier. https://doi.org/10.1016/0005-2728(95)00096-2
chicago: Sazanov, Leonid A, and Baz Jackson. “Cyclic Reactions Catalysed by Detergent-Dispersed
and Reconstituted Transhydrogenase from Beef Heart Mitochondria; Implications
for the Mechanism of Proton Translocation.” Biochimica et Biophysica Acta -
Bioenergetics. Elsevier, 1995. https://doi.org/10.1016/0005-2728(95)00096-2.
ieee: L. A. Sazanov and B. Jackson, “Cyclic reactions catalysed by detergent-dispersed
and reconstituted transhydrogenase from beef heart mitochondria; implications
for the mechanism of proton translocation,” Biochimica et Biophysica Acta -
Bioenergetics, vol. 1231, no. 3. Elsevier, pp. 304–312, 1995.
ista: Sazanov LA, Jackson B. 1995. Cyclic reactions catalysed by detergent-dispersed
and reconstituted transhydrogenase from beef heart mitochondria; implications
for the mechanism of proton translocation. Biochimica et Biophysica Acta - Bioenergetics.
1231(3), 304–312.
mla: Sazanov, Leonid A., and Baz Jackson. “Cyclic Reactions Catalysed by Detergent-Dispersed
and Reconstituted Transhydrogenase from Beef Heart Mitochondria; Implications
for the Mechanism of Proton Translocation.” Biochimica et Biophysica Acta -
Bioenergetics, vol. 1231, no. 3, Elsevier, 1995, pp. 304–12, doi:10.1016/0005-2728(95)00096-2.
short: L.A. Sazanov, B. Jackson, Biochimica et Biophysica Acta - Bioenergetics 1231
(1995) 304–312.
date_created: 2018-12-11T11:54:50Z
date_published: 1995-10-10T00:00:00Z
date_updated: 2022-06-29T15:04:47Z
day: '10'
doi: 10.1016/0005-2728(95)00096-2
extern: '1'
external_id:
pmid:
- '7578218'
intvolume: ' 1231'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.sciencedirect.com/science/article/pii/0005272895000962?via%3Dihub
month: '10'
oa: 1
oa_version: Published Version
page: 304 - 312
pmid: 1
publication: Biochimica et Biophysica Acta - Bioenergetics
publication_identifier:
issn:
- 0005-2728
publication_status: published
publisher: Elsevier
publist_id: '5142'
quality_controlled: '1'
status: public
title: Cyclic reactions catalysed by detergent-dispersed and reconstituted transhydrogenase
from beef heart mitochondria; implications for the mechanism of proton translocation
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 1231
year: '1995'
...
---
_id: '1947'
abstract:
- lang: eng
text: Mitochondrial transhydrogenase has been reported previously to be inhibited
by high, rather non-physiological concentrations (in the range of 2-20 mM) of
divalent cations. We show that the enzyme could be activated by low (from about
1 μM to 1 mM) concentrations of Ca2+ and Mg2+, which are within physiological
range. These results bring in line the effects observed with mitochondrial enzyme
to the findings with bacterial transhydrogenases. The activation of transhydrogenase
by divalent cations is interpreted as an increase in affinity of the NADP(H)-binding
site of the enzyme-NAD(H) complex. Reported effects of the metal ions could be
important for the enzyme function in vivo.
acknowledgement: 'This work was supported by a Wellcome Trust fellowship to L.A.S. '
article_processing_charge: No
article_type: original
author:
- first_name: Leonid A
full_name: Sazanov, Leonid A
id: 338D39FE-F248-11E8-B48F-1D18A9856A87
last_name: Sazanov
orcid: 0000-0002-0977-7989
- first_name: Julie
full_name: Jackson, Julie
last_name: Jackson
citation:
ama: Sazanov LA, Jackson J. Activation and inhibition of mitochondrial transhydrogenase
by metal ions. Biochimica et Biophysica Acta - Bioenergetics. 1993;1144(2):225-228.
doi:10.1016/0005-2728(93)90177-H
apa: Sazanov, L. A., & Jackson, J. (1993). Activation and inhibition of mitochondrial
transhydrogenase by metal ions. Biochimica et Biophysica Acta - Bioenergetics.
Elsevier. https://doi.org/10.1016/0005-2728(93)90177-H
chicago: Sazanov, Leonid A, and Julie Jackson. “Activation and Inhibition of Mitochondrial
Transhydrogenase by Metal Ions.” Biochimica et Biophysica Acta - Bioenergetics.
Elsevier, 1993. https://doi.org/10.1016/0005-2728(93)90177-H.
ieee: L. A. Sazanov and J. Jackson, “Activation and inhibition of mitochondrial
transhydrogenase by metal ions,” Biochimica et Biophysica Acta - Bioenergetics,
vol. 1144, no. 2. Elsevier, pp. 225–228, 1993.
ista: Sazanov LA, Jackson J. 1993. Activation and inhibition of mitochondrial transhydrogenase
by metal ions. Biochimica et Biophysica Acta - Bioenergetics. 1144(2), 225–228.
mla: Sazanov, Leonid A., and Julie Jackson. “Activation and Inhibition of Mitochondrial
Transhydrogenase by Metal Ions.” Biochimica et Biophysica Acta - Bioenergetics,
vol. 1144, no. 2, Elsevier, 1993, pp. 225–28, doi:10.1016/0005-2728(93)90177-H.
short: L.A. Sazanov, J. Jackson, Biochimica et Biophysica Acta - Bioenergetics 1144
(1993) 225–228.
date_created: 2018-12-11T11:54:52Z
date_published: 1993-09-13T00:00:00Z
date_updated: 2022-06-01T12:51:32Z
day: '13'
doi: 10.1016/0005-2728(93)90177-H
extern: '1'
external_id:
pmid:
- '8369341 '
intvolume: ' 1144'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.sciencedirect.com/science/article/pii/000527289390177H?via%3Dihub
month: '09'
oa_version: None
page: 225 - 228
pmid: 1
publication: Biochimica et Biophysica Acta - Bioenergetics
publication_identifier:
issn:
- 0005-2728
publication_status: published
publisher: Elsevier
publist_id: '5136'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Activation and inhibition of mitochondrial transhydrogenase by metal ions
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 1144
year: '1993'
...