Linked Life Data

21261288

Source:http://linkedlifedata.com/resource/pubmed/id/21261288

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
2011-3-15
pubmed:abstractText
Phenylalanine hydroxylase is a mononuclear non-heme iron protein that uses tetrahydropterin as the source of the two electrons needed to activate dioxygen for the hydroxylation of phenylalanine to tyrosine. Rapid-quench methods have been used to analyze the mechanism of a bacterial phenylalanine hydroxylase from Chromobacterium violaceum. Mo?ssbauer spectra of samples prepared by freeze-quenching the reaction of the enzyme-(57)Fe(II)-phenylalanine-6-methyltetrahydropterin complex with O(2) reveal the accumulation of an intermediate at short reaction times (20-100 ms). The Mo?ssbauer parameters of the intermediate (? = 0.28 mm/s, and |?E(Q)| = 1.26 mm/s) suggest that it is a high-spin Fe(IV) complex similar to those that have previously been detected in the reactions of other mononuclear Fe(II) hydroxylases, including a tetrahydropterin-dependent tyrosine hydroxylase. Analysis of the tyrosine content of acid-quenched samples from similar reactions establishes that the Fe(IV) intermediate is kinetically competent to be the hydroxylating intermediate. Similar chemical-quench analysis of a reaction allowed to proceed for several turnovers shows a burst of tyrosine formation, consistent with rate-limiting product release. All three data sets can be modeled with a mechanism in which the enzyme-substrate complex reacts with oxygen to form an Fe(IV)?O intermediate with a rate constant of 19 mM(-1) s(-1), the Fe(IV)?O intermediate hydroxylates phenylalanine with a rate constant of 42 s(-1), and rate-limiting product release occurs with a rate constant of 6 s(-1) at 5 °C.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
22
pubmed:volume
50
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1928-33
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Evidence for a high-spin Fe(IV) species in the catalytic cycle of a bacterial phenylalanine hydroxylase.
pubmed:affiliation
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural