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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
1999-5-7
pubmed:abstractText
Oxidation-reduction midpoint potentials were determined, as a function of pH, for the disulfide/dithiol couples of spinach and pea thioredoxins f, for spinach and Chlamydomonas reinhardtii thioredoxins m, for spinach ferredoxin:thioredoxin reductase (FTR), and for two enzymes regulated by thioredoxin f, spinach phosphoribulokinase (PRK) and the fructose-1,6-bisphosphatases (FBPase) from pea and spinach. Midpoint oxidation-reduction potential (Em) values at pH 7.0 of -290 mV for both spinach and pea thioredoxin f, -300 mV for both C. reinhardtii and spinach thioredoxin m, -320 mV for spinach FTR, -290 mV for spinach PRK, -315 mV for pea FBPase, and -330 mV for spinach FBPase were obtained. With the exception of spinach FBPase, titrations showed a single two-electron component at all pH values tested. Spinach FBPase exhibited a more complicated behavior, with a single two-electron component being observed at pH values >/= 7.0, but with two components being present at pH values <7.0. The slopes of plots of Em versus pH were close to the -60 mV/pH unit value expected for a process that involves the uptake of two protons per two electrons (i. e., the reduction of a disulfide to two fully protonated thiols) for thioredoxins f and m, for FTR, and for pea FBPase. The slope of the Em versus pH profile for PRK shows three regions, consistent with the presence of pKa values for the two regulatory cysteines in the region between pH 7.5 and 9.0.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5200-5
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Oxidation-reduction properties of chloroplast thioredoxins, ferredoxin:thioredoxin reductase, and thioredoxin f-regulated enzymes.
pubmed:affiliation
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't