Linked Life Data

7929130

Source:http://linkedlifedata.com/resource/pubmed/id/7929130

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
1994-11-4
pubmed:abstractText
The non-enzymatic deamidation at residues Asn-12 and Asn-38 of Escherichia coli phosphocarrier protein, HPr, and the repair of the resulting L-isoaspartyl (or beta-aspartyl) derivatives, HPr-1 and HPr-2, by recombinant human S-adenosylmethionine-dependent L-isoaspartate-(D-aspartate) O-methyltransferase (EC 2.1.1.77) were investigated. HPr is a component of the bacterial phosphoenolpyruvate:sugar phosphotransferase system that is involved in the concomitant translocation and phosphorylation of many hexose sugars. The major products of the deamidation reaction, L-isoaspartyl (or beta-aspartyl) residues at positions 12 and 38, were found to be substrates for the L-isoaspartate-(D-aspartate) O-methyltransferase, an enzyme active on a wide variety of peptides and proteins containing these abnormal residues. This enzyme has been shown to catalyze the first step in a process that can convert L-isoaspartyl residues in peptides to normal L-aspartyl residues. The affinity of a recombinant human methyltransferase for HPr-1, a form deamidated at Asn-38, was relatively poor (Km = 3.6 mM), while a greater affinity was found for HPr-2, a form deamidated at both Asn-12 and Asn-38 (Km = 197 microM). When HPr-2 was incubated with S-adenosylmethionine and the methyltransferase, the bulk of the L-isoaspartyl residues at position 12 was converted to L-aspartyl residues. The major-by-product was the D-isoaspartyl form. The conversion of L-isoaspartyl residues at position 38 to L-aspartyl residues was less complete, reflecting the lower affinity of the methyltransferase for this site. The phosphohydrolysis activity of the repaired form was found to be midway between the form containing only L-aspartyl residues at positions 12 and 38 and the deamidated HPr-2 form.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
269
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
24586-95
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Repair of spontaneously deamidated HPr phosphocarrier protein catalyzed by the L-isoaspartate-(D-aspartate) O-methyltransferase.
pubmed:affiliation
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569.
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