The cysteine S-H stretching mode reports on long-range conformational changes in pyruvate oxidase from E. coli.

The pyruvate oxidases from Escherichia coli (EcPOX) and Lactobacillus plantarum (LpPOX) are both thiamin-dependent flavoenzymes. Their sequence and structure are closely related, and they catalyse similar reactions-but they differ in their activity pattern: LpPOX is always highly active, EcPOX only when activated by lipids or limited proteolysis, both involving the protein's C-terminal 23 residues (the 'α-peptide'). Here, we relate the redox-induced infrared (IR) difference spectrum of EcPOX to its unusual activation mechanism.

A Triplet Label Extends Two-Dimensional Infrared Spectroscopy from Pico- to Microseconds.

In conventional two-dimensional infrared (2D-IR) spectroscopy, the inherently short vibrational lifetimes limit the time window to observe molecular dynamics typically to tens of picoseconds. The rather complex dynamics of organized molecular systems (e.g.

Proton-Coupled Electron Transport in Two Distinct CYBASC Paralogs of : A Comparative Characterization of Highly Conserved Tyrosine and Lysine Residues.

CYBASC proteins are ascorbate (AscH) reducible, diheme -containing integral membrane cytochrome proteins (cyt), which are proposed to be involved in AscH recycling and facilitation of iron absorption. Two distinct CYBASC paralogs from the plant , cyt-A (A-paralog) and cyt-B (B-paralog), have been found to differ in their visible-spectral characteristics and their interaction with AscH and ferric iron chelates. A previously determined crystal structure of the B-paralog provides the first insights into the structural organization of a CYBASC member and implies hydrogen bonding between the substrate AscH and the conserved lysine residues at positions 77 (B-K77) and 81 (B-K81).

Triptans for Acute Migraine Headache: Current Experience With Triptan Use and Prescription Habits in a Tertiary Care Headache Outpatient Clinic: An Observational Study.

Background: Triptans are recommended as first-line therapy in the acute phase of a migraine attack. We describe patterns of triptan use in a tertiary care headache outpatient clinic, particularly addressing factors that are associated with triptan discontinuation.

Methods: From December 2009 until August 2012, demographic and clinical data of consecutive patients with migraine were collected.

Caged CO(2) for the direct observation of CO(2)-consuming reactions.

CO(2)-consuming reactions, in particular carboxylations, play important roles in technical processes and in nature. Their kinetic behavior and the reaction mechanisms of carboxylating enzymes are difficult to study because CO(2) is inconvenient to handle as a gas, exists in equilibrium with bicarbonate in aqueous solution, and typically yields products that show no significant spectroscopic differences from the reactants in the UV/Vis range. Here we demonstrate the utility of 3-nitrophenylacetic acid and related compounds (caged CO(2)) in conjunction with infrared spectroscopy as widely applicable tools for the investigation of such reactions, permitting convenient measurement of the kinetics of CO(2) consumption.

Mucinous cystadenoma arising in a completely isolated infected ileal duplication cyst.

Gastrointestinal duplications are uncommon congenital lesions that can occur anywhere along the alimentary tract, and the symptoms of which generally develop during infancy or childhood. Completely isolated duplication cysts are an extremely rare variant of duplication, where no communication between the cyst and the adjacent bowel segment is present. We report the unique case of an adult who presented with right lower abdominal pain and systemic signs of inflammation caused by infection of a completely isolated ileal duplication cyst.

Brain-derived neurotrophic factor in primary headaches.

Brain derived neurotrophic factor (BDNF) is associated with pain modulation and central sensitization. Recently, a role of BDNF in migraine and cluster headache pathophysiology has been suspected due to its known interaction with calcitonin gene-related peptide. Bi-center prospective study was done enrolling four diagnostic groups: episodic migraine with and without aura, episodic cluster headache, frequent episodic tension-type headache, and healthy individuals.

Molecular mechanism of uncaging CO2 from nitrophenylacetate provides general guidelines for improved ortho-nitrobenzyl cages.

Femtosecond spectroscopy and quantum chemical calculations provide detailed insights into the specificities of the uncaging mechanism of CO2 from ortho-, meta-, and para-nitrophenylacetate. The emerging general principles allow a rational design of improved ortho-nitrophenyl cages for chemical and biological applications.

New insights into structure-function relationships of oxalyl CoA decarboxylase from Escherichia coli.

The gene yfdU from Escherichia coli encodes a putative oxalyl coenzyme A decarboxylase, a thiamine diphosphate-dependent enzyme that is potentially involved in the degradation of oxalate. The enzyme has been purified to homogeneity. The kinetic constants for conversion of the substrate oxalyl coenzyme A by the enzyme in the absence and presence of the inhibitor coenzyme A, as well as in the absence and presence of the activator adenosine 5'-diphosphate, were determined using a novel continuous optical assay.

[Implementation of thrombolysis in acute stroke--10-year results of the Innsbruck stroke registry].

Background: Randomized controlled trials have yielded evidence for the efficacy and safety of intravenous alteplase in the therapy of acute ischemic stroke. A large patient registry has recently confirmed the safe implementation of this therapy in the clinical routine setting.

Methods: Between January 1998 and December 2007 302 stroke patients were treated with 0.

Phenotypical variability of post-partum reversible cerebral vasoconstriction syndrome.

Reversible cerebral vasoconstriction syndrome is recognized increasingly as a complication of the postpartum period. Our series of four cases illustrates its phenotypical variability, summarizes the diagnostic work-up, and outlines potential treatment strategies for this usually benign but sometimes disabling and life-threatening disease.

Covalently bound substrate at the regulatory site of yeast pyruvate decarboxylases triggers allosteric enzyme activation.

The mechanism by which the enzyme pyruvate decarboxylase from two yeast species is activated allosterically has been elucidated. A total of seven three-dimensional structures of the enzyme, of enzyme variants, or of enzyme complexes from two yeast species, three of them reported here for the first time, provide detailed atomic resolution snapshots along the activation coordinate. The prime event is the covalent binding of the substrate pyruvate to the side chain of cysteine 221, thus forming a thiohemiketal.

[Juvenile stroke--results from the Austrian Stroke Registry].

In recent years, many aspects of juvenile stroke have been addressed in medium-sized case series. We have analyzed stroke severity, etiology, risk factors, and outcome in different age groups in the large dataset of the Austrian Stroke Unit Registry. In the nationwide Austrian Stroke Unit Registry 13,440 men and women with ischemic stroke or transient ischemic attack were recorded between March 2003 and February 2007.

Crystallization and preliminary X-ray diffraction analysis of full-length and proteolytically activated pyruvate oxidase from Escherichia coli.

The thiamine diphosphate- and flavin-dependent peripheral membrane enzyme pyruvate oxidase from Escherichia coli (EcPOX) has been crystallized in the full-length form and as a proteolytically activated C-terminal truncation variant which lacks the last 23 amino acids (Delta23 EcPOX). Crystals were grown by the hanging-drop vapour-diffusion method using either protamine sulfate (full-length EcPOX) or 2-methyl-2,4-pentanediol (Delta23 EcPOX) as precipitants. Native data sets were collected at a X-ray home source to a resolution of 2.

Strain and near attack conformers in enzymic thiamin catalysis: X-ray crystallographic snapshots of bacterial transketolase in covalent complex with donor ketoses xylulose 5-phosphate and fructose 6-phosphate, and in noncovalent complex with acceptor aldose ribose 5-phosphate.

Transketolase is a prominent thiamin diphosphate-dependent enzyme in sugar metabolism that catalyzes the reversible transfer of a 2-carbon dihydroxyethyl fragment between a donor ketose and an acceptor aldose. The X-ray structures of transketolase from E. coli in a covalent complex with donor ketoses d-xylulose 5-phosphate (X5P) and d-fructose 6-phosphate (F6P) at 1.

The crystal structure of pyruvate decarboxylase from Kluyveromyces lactis. Implications for the substrate activation mechanism of this enzyme.

The crystal structure of pyruvate decarboxylase from Kluyveromyces lactis has been determined to 2.26 A resolution. Like other yeast enzymes, Kluyveromyces lactis pyruvate decarboxylase is subject to allosteric substrate activation.

The catalytic cycle of a thiamin diphosphate enzyme examined by cryocrystallography.

Enzymes that use the cofactor thiamin diphosphate (ThDP, 1), the biologically active form of vitamin B(1), are involved in numerous metabolic pathways in all organisms. Although a theory of the cofactor's underlying reaction mechanism has been established over the last five decades, the three-dimensional structures of most major reaction intermediates of ThDP enzymes have remained elusive. Here, we report the X-ray structures of key intermediates in the oxidative decarboxylation of pyruvate, a central reaction in carbon metabolism catalyzed by the ThDP- and flavin-dependent enzyme pyruvate oxidase (POX)3 from Lactobacillus plantarum.

Radical phosphate transfer mechanism for the thiamin diphosphate- and FAD-dependent pyruvate oxidase from Lactobacillus plantarum. Kinetic coupling of intercofactor electron transfer with phosphate transfer to acetyl-thiamin diphosphate via a transient FAD semiquinone/hydroxyethyl-ThDP radical pair.

The thiamin diphosphate (ThDP)- and flavin adenine dinucleotide (FAD)-dependent pyruvate oxidase from Lactobacillus plantarum catalyses the conversion of pyruvate, inorganic phosphate, and oxygen to acetyl-phosphate, carbon dioxide, and hydrogen peroxide. Central to the catalytic sequence, two reducing equivalents are transferred from the resonant carbanion/enamine forms of alpha-hydroxyethyl-ThDP to the adjacent flavin cofactor over a distance of approximately 7 A, followed by the phosphorolysis of the thereby formed acetyl-ThDP. Pre-steady-state and steady-state kinetics using time-resolved spectroscopy and a 1H NMR-based intermediate analysis indicate that both processes are kinetically coupled.

The role of Val-265 for flavin adenine dinucleotide (FAD) binding in pyruvate oxidase: FTIR, kinetic, and crystallographic studies on the enzyme variant V265A.

In pyruvate oxidase (POX) from Lactobacillus plantarum, valine 265 participates in binding the cofactor FAD and is responsible for the strained conformation of its isoalloxazine moiety that is visible in the crystal structure of POX. The contrasting effects of the conservative amino acid exchange V265A on the enzyme's catalytic properties, cofactor affinity, and protein structure were investigated. The most prominent effect of the exchange was observed in the 2.

Investigation of the pathway for inter-copper electron transfer in peptidylglycine alpha-amidating monooxygenase.

Peptidylglycine alpha-amidating monooxygenase catalyzes the oxidative cleavage of glycine extended peptides at their terminus. In the course of the reaction, there is a requisite long-range electron transfer between the two copper centers (CuH and CuM) located in the hydroxylating domain. This communication presents data that argue against the participation of the extended peptide backbone of substrate in the long-range electron transfer.

Redox-triggered FTIR difference spectra of FAD in aqueous solution and bound to flavoproteins.

Flavin adenine dinucleotide (FAD) and three different flavoproteins in aqueous solution were subjected to redox-triggered Fourier transform infrared difference spectroscopy. The acquired vibrational spectra show a great number of positive and negative peaks, pertaining to the oxidized and reduced state of the molecule, respectively. Density functional theory calculations on the B3LYP/6-31G(d) level were employed to assign several of the observed bands to vibrational modes of the isoalloxazine moiety of the flavin cofactor in both its oxidized and, for the first time, its reduced state.