Linked Life Data

3132206

Source:http://linkedlifedata.com/resource/pubmed/id/3132206

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1988-7-15
pubmed:abstractText
Reaction of Bacillus cereus phosphonoacetaldehyde hydrolase (phosphonatase) with phosphonoacetaldehyde or acetaldehyde in the presence of NaBH4 resulted in complete loss of enzymatic activity. Treatment of phosphonatase with NaBH4 in the absence of substrate or product had no effect on catalysis. Inactivation of phosphonatase with [3H]NaBH4 and phosphonoacetaldehyde, NaBH4 and [14C]acetaldehyde, or NaBH4 and [2-3H]phosphonoacetaldehyde produced in each instance radiolabeled enzyme. The nature of the covalent modification was investigated by digesting the radiolabeled enzyme preparations with trypsin and by separating the tryptic peptides with HPLC. Analysis of the peptide fractions revealed that incorporation of the 3H- or 14C-radiolabel into the protein was reasonably selective for an amino acid residue found in a peptide fragment observed in each of the three trypsin digests. Sequence analysis of the 3H-labeled peptide fragment isolated from the digest of the [2-3H]phosphonoacetaldehyde/NaBH4-treated enzyme identified N epsilon-ethyllysine as the radiolabeled amino acid. The ability of the phosphonatase competitive inhibitor (Ki = 230 +/- 20 microM) acetonylphosphonate to protect the enzyme from phosphonoacetaldehyde/NaBH4-induced inactivation suggested that the reactive lysine residue is located in the enzyme active site. Comparison of the relative effectiveness of phosphonoacetaldehyde and acetaldehyde as phosphonatase inactivators showed that the N-ethyllysine imine that is reduced by the NaBH4 is derived from the corresponding N-(phosphonoethyl) imine. On the basis of these findings, a catalytic mechanism for for phosphonatase is proposed in which phosphonoacetaldehyde is activated for P-C bond cleavage by formation of a Schiff base with an active-site lysine. Accordingly, an N-ethyllsysine enamine rather than the high-energy acetaldehyde enolate anion is displaced from the phosphorus.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2229-34
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Investigation of the Bacillus cereus phosphonoacetaldehyde hydrolase. Evidence for a Schiff base mechanism and sequence analysis of an active-site peptide containing the catalytic lysine residue.
pubmed:affiliation
Department of Chemistry and Biochemistry, University of Maryland, College Park 20742.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't