Linked Life Data

7138813

Source:http://linkedlifedata.com/resource/pubmed/id/7138813

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
1983-1-19
pubmed:abstractText
D-beta-Hydroxybutyrate dehydrogenase (BDH), purified as soluble, lipid-free apoenzyme (inactive) from either beef heart or rat liver mitochondria, can be reactivated by short-chain lecithins in the monomeric state. The enzyme was reactivated with dihexanoyl- [PC(6:0)], diheptanoyl- [PC(7:0)], and dioctanoyllecithins [PC(8:0)]. The titration curves of enzyme activity as a function of the phospholipid concentration are consistent with a model in which the enzyme contains two identical, noninteracting lecithin binding sites. The simultaneous occupation of these sites (via an equilibrium random mechanism) is required to activate the apoenzyme. Similar results were obtained with both rat liver and beef heart apoenzymes. The maximal velocities obtained with the different lecithins were similar [110-140 mumol of NAD+ reduced min-1 (mg of protein)-1]. The KL values (the apparent dissociation constants of the lecithin-site complexes) were 1.2 X 10(-4) M [PC(8:0)], 1.5 X 10(-3) M [PC(7:0)], and 4.5 X 10(-3) M [PC(6:0)] at 37 degrees C. This was confirmed by using phospholipase A2 to compete with the dehydrogenase for the lecithin monomers. Comparison of the delta G degrees values for complex formation with the different lecithins shows an average contribution of approximately 2.4 kJ/mol (0.9RT) per CH2 group. The interaction of the apolar moiety of lecithin with the protein seems to be essential for effective binding of phosphatidylcholine to apoBDH. The delta G degrees values, when combined with the estimated delta H degrees values, suggest that the binding of lecithin to the apoenzyme is approximately 60% enthalpy and approximately 40% entropy driven.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
3
pubmed:volume
21
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3899-908
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Reactivation of D-beta-hydroxybutyrate dehydrogenase with short-chain lecithins: stoichiometry and kinetic mechanism.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't