Linked Life Data

16042374

Source:http://linkedlifedata.com/resource/pubmed/id/16042374

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
30
pubmed:dateCreated
2005-7-26
pubmed:abstractText
The Streptomyces R61 dd-peptidase, a functional model for penicillin-binding proteins, catalyzes the hydrolysis and aminolysis of d-alanyl-d-alanine-terminating peptides by specific amines. In vivo, this reaction completes bacterial cell wall biosynthesis. For in vitro studies of this enzyme to date, various nonspecific acyl-donor substrates have been employed. Recently, however, a peptidoglycan-mimetic peptide substrate, glycyl-l-alpha-amino-epsilon-pimelyl-d-alanyl-d-alanine, has been described that is much more specific for this enzyme. In this paper, we describe the synthesis and kinetic characterization of an analogous thiolester substrate, 3-(N-glycyl-l-cysteinyl)-propanoyl-d-alanyl-d-thiolactate, that the enzyme hydrolyzes and aminolyzes very efficiently (k(cat)/K(m) = 1.0 x 10(7) s(-)(1) M(-)(1)). Direct or indirect, by means of a thiol trap, spectrophotometric monitoring of the reactions of this substrate is readily achieved. Deacylation of the enzyme is rate-determining under substrate saturation conditions, and therefore the aminolysis reaction can be directly studied. The results show that d-amino acids and certain Gly-l-Xaa dipeptides and tripeptides may act as acyl acceptors at the active site of the enzyme. d-Phenylalanine and Gly-l-Phe were the most effective d-amino acid and dipeptide acceptors, respectively. On the basis of the dual specificity of the active site for acceptors (d-amino acids and Gly-l-Xaa peptides), "dual function" acceptors were designed and synthesized. Two of these, aminomalon-(N-ethyl)amide and aminomalon-(N-phenethyl)amide, were particularly effective. It did seem, however, that the observed rates of reaction of these very effective acceptors may be limited by some common, possibly physical, step. More extended, peptidoglycan-like, acceptors were found to be essentially unreactive. The reasons for this counterintuitive behavior are discussed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Chromogenic Compounds, http://linkedlifedata.com/resource/pubmed/chemical/Dipeptides, http://linkedlifedata.com/resource/pubmed/chemical/Esters, http://linkedlifedata.com/resource/pubmed/chemical/N-glycylalanine, http://linkedlifedata.com/resource/pubmed/chemical/Oligopeptides, http://linkedlifedata.com/resource/pubmed/chemical/Peptidyl Transferases, http://linkedlifedata.com/resource/pubmed/chemical/Serine-Type D-Ala-D-Ala..., http://linkedlifedata.com/resource/pubmed/chemical/Sulfhydryl Compounds, http://linkedlifedata.com/resource/pubmed/chemical/glycyl-L-alpha-amino-epsilon-pimelyl..., http://linkedlifedata.com/resource/pubmed/chemical/glycyl-alanyl-phenylalanine, http://linkedlifedata.com/resource/pubmed/chemical/glycylleucine, http://linkedlifedata.com/resource/pubmed/chemical/glycylphenylalanine
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
2
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9971-9
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Transpeptidation reactions of a specific substrate catalyzed by the streptomyces R61 DD-peptidase: characterization of a chromogenic substrate and acyl acceptor design.
pubmed:affiliation
Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, N.I.H., Extramural