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Regulation of violaxanthin de-epoxidase activity by pH and ascorbate concentration

Bratt, Charlotte Eva; Arvidsson, Per-Ola; Carlsson, Marie and Åkerlund, Hans-Erik LU (1995) In Photosynthesis Research 45(2). p.169-175
Abstract
The activity of violaxanthin de-epoxidase has been studied both in isolated thylakoids and after partial purification, as a function of pH and ascorbate concentration. We demonstrate that violaxanthin de-epoxidase has a Km for ascorbate that is strongly dependent on pH, with values of 10, 2.5, 1.0 and 0.3 mM at pH 6.0, 5.5, 5.0 and 4.5, respectively. These values can be expressed as a single Km±0.1±0.02 mM for the acid form of ascorbate. Release of the protein from the thylakoids by sonication was also found to be strongly pH dependent with a cooperativity of 4 with respect to protons and with an inflexion point at pH 6.7. These results can explain some of the discrepancies reported in the literature and provide a more consistent view of... (More)
The activity of violaxanthin de-epoxidase has been studied both in isolated thylakoids and after partial purification, as a function of pH and ascorbate concentration. We demonstrate that violaxanthin de-epoxidase has a Km for ascorbate that is strongly dependent on pH, with values of 10, 2.5, 1.0 and 0.3 mM at pH 6.0, 5.5, 5.0 and 4.5, respectively. These values can be expressed as a single Km±0.1±0.02 mM for the acid form of ascorbate. Release of the protein from the thylakoids by sonication was also found to be strongly pH dependent with a cooperativity of 4 with respect to protons and with an inflexion point at pH 6.7. These results can explain some of the discrepancies reported in the literature and provide a more consistent view of zeaxanthin formation in vivo. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Photosynthesis Research
volume
45
issue
2
pages
169 - 175
publisher
Springer
external identifiers
  • scopus:34249758236
ISSN
0166-8595
DOI
10.1007/BF00032588
language
English
LU publication?
yes
id
bc450253-4efc-4fd9-8b34-4d938be80ba2 (old id 1494411)
date added to LUP
2009-10-23 12:06:19
date last changed
2017-11-05 04:27:55
@article{bc450253-4efc-4fd9-8b34-4d938be80ba2,
  abstract     = {The activity of violaxanthin de-epoxidase has been studied both in isolated thylakoids and after partial purification, as a function of pH and ascorbate concentration. We demonstrate that violaxanthin de-epoxidase has a Km for ascorbate that is strongly dependent on pH, with values of 10, 2.5, 1.0 and 0.3 mM at pH 6.0, 5.5, 5.0 and 4.5, respectively. These values can be expressed as a single Km±0.1±0.02 mM for the acid form of ascorbate. Release of the protein from the thylakoids by sonication was also found to be strongly pH dependent with a cooperativity of 4 with respect to protons and with an inflexion point at pH 6.7. These results can explain some of the discrepancies reported in the literature and provide a more consistent view of zeaxanthin formation in vivo.},
  author       = {Bratt, Charlotte Eva and Arvidsson, Per-Ola and Carlsson, Marie and Åkerlund, Hans-Erik},
  issn         = {0166-8595},
  language     = {eng},
  number       = {2},
  pages        = {169--175},
  publisher    = {Springer},
  series       = {Photosynthesis Research},
  title        = {Regulation of violaxanthin de-epoxidase activity by pH and ascorbate concentration},
  url          = {http://dx.doi.org/10.1007/BF00032588},
  volume       = {45},
  year         = {1995},
}