Linked Life Data

15958186

Source:http://linkedlifedata.com/resource/pubmed/id/15958186

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2005-6-16
pubmed:abstractText
We report a new continuous spectrophotometric assay for human cystathionine beta-synthase (hCBS). This assay relies upon the finding that hCBS will take cysteamine in place of L-homocysteine, thereby producing thialysine. Thialysine is, in turn, decarboxylated by lysine decarboxylase, releasing CO2 that is monitored by the sequential action of phosphoenolpyruvate carboxylase and L-malate dehydrogenase. The decrease in absorbance at 340 nm is monitored as reduced nicotinamide adenine dinucleotide is consumed. Using this four-enzyme couple, we find that Km(app) = 1.2+/-0.2 mM for L-serine and 5.6+/-2.2 mM for cysteamine, with kcat = 1.3+/-0.1s(-1) for the formation of thialysine by hCBS. For comparison purposes, the same hCBS reaction was monitored via a radioactive single time point assay using 14C-(C-1)-labeled L-serine and cysteamine as substrates, counting the thialysine product, following ion exchange chromatography. This assay yielded Km(app) = 2.2+/-0.5 mM for L-serine and 6.6+/-2.2 for cysteamine, with kcat = 2.5+/-0.4 s(-1). These numbers indicate that, although it possesses a shortened carbon chain and lacks a carboxyl group, cysteamine displays a catalytic efficiency (kcat/Km) with hCBS that is within an order of magnitude of that observed with its natural thiol cosubstrate, L-homocysteine.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0003-2697
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
342
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
103-10
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
A continuous spectrophotometric assay for human cystathionine beta-synthase.
pubmed:affiliation
Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Evaluation Studies