Linked Life Data

7104302

Source:http://linkedlifedata.com/resource/pubmed/id/7104302

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1982-10-12
pubmed:abstractText
Sulfite reductase (SiR) has been purified to homogeneity from spinach leaves. Two forms of the enzyme were separated by hydroxylapatite chromatography. One, with subunit Mr 69 000 appears to be proteolytically cleaved to give rise to the other, with subunit Mr 63 000, during the purification procedure. The two species have identical catalytic activities (on a per heme basis) when reduced methylviologen (MV+) or ferredoxin (Fdr) is used as electron donor for sulfite reduction, and they exhibit nearly identical optical and EPR spectra. Both enzyme forms exist in 50 mM phosphate buffer (pH 7.7) primarily as dimers at 20 degrees C. Spinach SiR contains 1 mol of siroheme and one Fe4S4 center per subunit. The heme iron is the high spin Fe3+ state in the enzyme as isolated. Near quantitative reduction of the Fe4S4 center by dithionite could be achieved if SiR was either converted to the CO complex or treated with 80% dimethyl sulfoxide. Spinach SiR and nitrite reductase (NiR) both catalyze Fdr-or MV+-de-pendent six-electron reductions of SO3(2)- and NO2-, as well as the two electron reduction of NH2OH. Vmax values are highest with the nitrogenous substrates. However, the Km of SiR for So3(2-), and of NiR for NO2-, is at least 2 orders of magnitude less than with either of the other substrates. Rates of reduction with Fdr as electron donor are greater than with MV+ as donor, No immunological cross-reaction could be detected between spinach SiR and Escherichia coli SiR or between spinach SiR and NiR.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
21
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2892-904
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Spinach siroheme enzymes: Isolation and characterization of ferredoxin-sulfite reductase and comparison of properties with ferredoxin-nitrite reductase.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.