Linked Life Data

10529244

Source:http://linkedlifedata.com/resource/pubmed/id/10529244

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
42
pubmed:dateCreated
1999-11-24
pubmed:abstractText
Porphobilinogen synthases (PBGS) are metalloenzymes that catalyze the first common step in tetrapyrrole biosynthesis. The PBGS enzymes have previously been categorized into four types (I-IV) by the number of Zn(2+) and/or Mg(2+) utilized at three different metal binding sites termed A, B, and C. In this study Pseudomonas aeruginosa PBGS is found to bind only four Mg(2+) per octamer as determined by atomic absorption spectroscopy, in the presence or absence of substrate/product. This is the lowest number of bound metal ions yet found for PBGS where other enzymes bind 8-16 divalent ions. These four Mg(2+) allosterically stimulate a metal ion independent catalytic activity, in a fashion dependent upon both pH and K(+). The allosteric Mg(2+) of PBGS is located in metal binding site C, which is outside the active site. No evidence is found for metal binding to the potential high-affinity active site metal binding sites A and/or B. P. aeruginosa PBGS was investigated using Mn(2+) as an EPR probe for Mg(2+), and the active site was investigated using [3,5-(13)C]porphobilinogen as an NMR probe. The magnetic resonance data exclude the direct involvement of Mg(2+) in substrate binding and product formation. The combined data suggest that P. aeruginosa PBGS represents a new type V enzyme. Type V PBGS has the remarkable ability to synthesize porphobilinogen in a metal ion independent fashion. The total metal ion stoichiometry of only 4 per octamer suggests half-sites reactivity.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13976-82
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Pseudomonas aeruginosa contains a novel type V porphobilinogen synthase with no required catalytic metal ions.
pubmed:affiliation
Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't