Linked Life Data

12733906

Source:http://linkedlifedata.com/resource/pubmed/id/12733906

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
2003-5-7
pubmed:abstractText
Phenylalanine hydroxylase (PAH) is a tetrahydrobiopterin-dependent, nonheme iron enzyme that catalyzes the hydroxylation of L-Phe to L-Tyr in the rate-limiting step of phenylalanine catabolism. This reaction is tightly coupled in the wild-type enzyme to oxidation of the tetrahydropterin cofactor. Dysfunction of PAH activity in humans leads to the disease phenylketonuria (PKU). We have investigated two PKU-inducing mutants, Arg158Gln and Glu280Lys, using kinetic methods, magnetic circular dichrosim (MCD) spectroscopy, and X-ray absorption spectroscopy (XAS). Analysis of the products produced by the mutant enzymes shows that although both oxidize pterin at more than twice the rate of wild-type enzyme, these reactions are only approximately 20% coupled to production of L-Tyr. Previous MCD and XAS studies had demonstrated that the resting Fe(II) site is six-coordinate in the wild-type enzyme and converts to a five-coordinate site when both L-Phe and reduced pterin are present in the active site. Although the Arg158Gln mutant forms the five-coordinate site when both cosubstrates are bound, the Fe(II) site of the Glu280Lys mutant remains six-coordinate. These results provide insight into the PAH reaction and disease mechanism at a molecular level, indicating that the first step of the mechanism is formation of a peroxy-pterin species, which subsequently reacts with the Fe(II) site if the pterin is properly oriented for formation of an Fe-OO-pterin bridge and an open coordination position is available on the Fe(II).
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
125
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5677-86
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Spectroscopic and kinetic studies of PKU-inducing mutants of phenylalanine hydroxylase: Arg158Gln and Glu280Lys.
pubmed:affiliation
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.