Linked Life Data

10995249

Source:http://linkedlifedata.com/resource/pubmed/id/10995249

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
38
pubmed:dateCreated
2000-10-16
pubmed:abstractText
Bromonitromethane is an inefficient suicide substrate for glucose oxidase (in contrast to the case of CH(3)CCl=NO(2)(-) and D-amino acid oxidase) because, in the enzyme-substrate encounter step, the required ionization states of enzyme (EH(0)(+), pK(a) approximately 3.5) and substrate (CHBr=NO(2)(-), pK(a) approximately 8.3) cannot be highly populated simultaneously. Because reprotonation of CHBr=NO(2)(-) is rapid at the pH value used for the assay of glucose oxidase, presentation of the enzyme with the preformed anion could not be exploited in this case. We circumvent this difficulty by allowing the enzyme to reductively dehalogenate CHBr(2)NO(2), thereby generating the desired protonically unstable suicide substrate in situ (E(r) + CHBr(2)NO(2) --> E(o) + CHBr=NO(2)(-) + HBr + H(+)). Irreversible inactivation of the enzyme, because of the formation of a dead-end N-5 formylflavin adduct, is more than 100-fold faster when CHBr=NO(2)(-) is generated in situ than when it is externally applied. The remaining competitive fates of CHBr=NO(2)(-) at the active site are protonation and release or oxidation to HCOBr (or HCONO(2)). Strong support for these conclusions comes from (1) the brisk evolution of CH(3)CBr=NO(2)(-) (which is too bulky to act further as an efficient suicide substrate) from the enzyme-catalyzed reductive debromination of CH(3)CBr(2)NO(2), (2) the 1:1 stoichiometry of enzyme inactivation, and (3) the identification of the modified flavin as 5-formyl-1, 5-dihydro-FAD.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/2-nitropropane dioxygenase, http://linkedlifedata.com/resource/pubmed/chemical/Anions, http://linkedlifedata.com/resource/pubmed/chemical/Bromine, http://linkedlifedata.com/resource/pubmed/chemical/Dioxygenases, http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Inhibitors, http://linkedlifedata.com/resource/pubmed/chemical/Enzyme Precursors, http://linkedlifedata.com/resource/pubmed/chemical/Flavin-Adenine Dinucleotide, http://linkedlifedata.com/resource/pubmed/chemical/Glucose, http://linkedlifedata.com/resource/pubmed/chemical/Glucose Oxidase, http://linkedlifedata.com/resource/pubmed/chemical/Methane, http://linkedlifedata.com/resource/pubmed/chemical/Nitroparaffins, http://linkedlifedata.com/resource/pubmed/chemical/Oxygenases, http://linkedlifedata.com/resource/pubmed/chemical/Protons, http://linkedlifedata.com/resource/pubmed/chemical/flavin semiquinone, http://linkedlifedata.com/resource/pubmed/chemical/nitromethane
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11808-17
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Active site generation of a protonically unstable suicide substrate from a stable precursor: glucose oxidase and dibromonitromethane.
pubmed:affiliation
Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. djp39807@glaxowellcome.com
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't