Linked Life Data

10787404

Source:http://linkedlifedata.com/resource/pubmed/id/10787404

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
27
pubmed:dateCreated
2000-8-16
pubmed:abstractText
The photoreceptor cGMP phosphodiesterase (PDE6) plays a key role in vertebrate vision, but its enzymatic mechanism and the roles of metal ion co-factors have yet to be determined. We have determined the amount of endogenous Zn(2+) in rod PDE6 and established a requirement for tightly bound Zn(2+) in catalysis. Purified PDE6 contained 3-4-g atoms of zinc/mole, consistent with an initial content of two tightly bound Zn(2+)/catalytic subunit. PDE with only tightly bound Zn(2+) and no free metal ions was inactive, but activity was fully restored by Mg(2+), Mn(2+), Co(2+), or Zn(2+). Mn(2+), Co(2+), and Zn(2+) also induced aggregation and inactivation at higher concentrations and longer times. Removal of 93% of the tightly bound Zn(2+) by treatment with dipicolinic acid and EDTA at pH 6.0 resulted in almost complete loss of activity in the presence of Mg(2+). This activity loss was blocked almost completely by Zn(2+), less potently by Co(2+) and almost not at all by Mg(2+), Mn(2+), or Cu(2+). The lost activity was restored by the addition of Zn(2+), but Co(2+) restored only 13% as much activity, and other metals even less. Thus tightly bound Zn(2+) is required for catalysis but could also play a role in stabilizing the structure of PDE6, whereas distinct sites where Zn(2+) is rapidly exchanged are likely occupied by Mg(2+) under physiological conditions.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
275
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
20572-7
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:10787404-3',5'-Cyclic-GMP Phosphodiesterases, pubmed-meshheading:10787404-Animals, pubmed-meshheading:10787404-Binding Sites, pubmed-meshheading:10787404-Cations, Divalent, pubmed-meshheading:10787404-Cattle, pubmed-meshheading:10787404-Chelating Agents, pubmed-meshheading:10787404-Cyclic Nucleotide Phosphodiesterases, Type 6, pubmed-meshheading:10787404-Enzyme Activation, pubmed-meshheading:10787404-Enzyme Stability, pubmed-meshheading:10787404-Eye Proteins, pubmed-meshheading:10787404-Kinetics, pubmed-meshheading:10787404-Metalloproteins, pubmed-meshheading:10787404-Picolinic Acids, pubmed-meshheading:10787404-Protein Binding, pubmed-meshheading:10787404-Retinal Rod Photoreceptor Cells, pubmed-meshheading:10787404-Spectrophotometry, Atomic, pubmed-meshheading:10787404-Zinc
pubmed:year
2000
pubmed:articleTitle
Multiple zinc binding sites in retinal rod cGMP phosphodiesterase, PDE6alpha beta.
pubmed:affiliation
Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't