Staphylococcus aureus uses IsdG and IsdI to convert heme into a mixture of staphylobilin isomers, 15-oxo-β-bilirubin and 5-oxo-δ-bilirubin, formaldehyde, and iron. The highly ruffled heme found in the heme-IsdI and IsdG complexes has been proposed to be responsible for the unique heme degradation products. We employed resonance Raman (RR) and electron paramagnetic resonance (EPR) spectroscopies to examine the coordination and electronic structures of heme bound to IsdG and IsdI. Heme complexed to IsdG and IsdI is coordinated by a neutral histidine. The trans ligand is hydroxide in the ferric alkaline form of both proteins. In the ferric neutral form at pH 6.0, heme is six-coordinated with water as the sixth ligand for IsdG and is in the mixture of the five-coordinated and six-coordinated species for IsdI. In the ferrous CO-bound form, CO is strongly hydrogen bonded with a distal residue. The marker lines, ν2 and ν3, appear at frequencies that are distinct from other proteins having planar hemes. The EPR spectra for the ferric hydroxide and cyanide states might be explained by assuming the thermal mixing of the d-electron configurations, (dxy)2(dxz,dyz)3 and (dxz,dyz)4(dxy)1. The fraction for the latter becomes larger for the ferric cyanide form. In the ferric neutral state at pH 6.0, the quantum mechanical mixing of the high and intermediate spin configurations might explain the peculiar frequencies of ν2 and ν3 in the RR spectra. The heme ruffling imposed by IsdG and IsdI gives rise to unique electronic structures of heme, which are expected to modulate the first and subsequent steps of the heme oxygenation.

• MeSH
• bakteriální proteiny chemie   MeSH
• elektronová paramagnetická rezonance MeSH
• hem chemie   MeSH
• lidé MeSH
• oxid uhelnatý chemie   MeSH
• oxygenasy se smíšenou funkcí chemie   MeSH
• oxygenasy chemie   MeSH
• Ramanova spektroskopie MeSH
• stafylokokové infekce mikrobiologie   MeSH
• Staphylococcus aureus chemie   MeSH
• vodíková vazba MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Lytic polysaccharide monooxygenases (LPMOs) are industrially important oxidoreductases employed in lignocellulose saccharification. Using advanced time-resolved mass spectrometric techniques, we elucidated the structural determinants for substrate-mediated stabilization of the fungal LPMO9C from Neurosporacrassa during catalysis. LPMOs require a reduction in the active-site copper for catalytic activity. We show that copper reduction in NcLPMO9C leads to structural rearrangements and compaction around the active site. However, longer exposure to the reducing agent ascorbic acid also initiated an uncoupling reaction of the bound oxygen species, leading to oxidative damage, partial unfolding, and even fragmentation of NcLPMO9C. Interestingly, no changes in the hydrogen/deuterium exchange rate were detected upon incubation of oxidized or reduced LPMO with crystalline cellulose, indicating that the LPMO-substrate interactions are mainly side-chain mediated and neither affect intraprotein hydrogen bonding nor induce significant shielding of the protein surface. On the other hand, we observed a protective effect of the substrate, which slowed down the autooxidative damage induced by the uncoupling reaction. These observations further complement the picture of structural changes during LPMO catalysis.

• MeSH
• celulosa chemie   MeSH
• fungální proteiny chemie   MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• hmotnostní spektrometrie MeSH
• katalytická doména MeSH
• katalýza MeSH
• koncentrace vodíkových iontů MeSH
• konformace proteinů MeSH
• kyslík chemie   MeSH
• lignin chemie   MeSH
• měď chemie   MeSH
• Neurospora crassa enzymologie   MeSH
• oxidační stres MeSH
• oxidoreduktasy chemie   MeSH
• oxygenasy se smíšenou funkcí chemie   MeSH
• polysacharidy chemie   MeSH
• reaktivní formy kyslíku chemie   MeSH
• substrátová specifita MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Biogenic amines are common biologically active substances extended within the whole animal kingdom where they play vital roles as signal transducer as well as regulator of cell functions. One of these biogenic amines called octopamine (OA) is synthesized from tyramine (TA) by the catalysis of tyramine-β-hydroxylase (TβH) originated in the insect nervous system. Both TA and OA act as neurotransmitters, neurohormones and neuromodulators in the arthropod nervous system. Herein, the inhibitory activity of 1-arylimidazole-2(3H)-thiones (AITs) was tested on cloned Drosophila tyramine-β-hydroxylase (DmTβH) expressed in Bombyx mori strain. Radiolabelled (3)H-TA was used to analyze the activity of AITs exhibited inhibitory effects on DmTβH, whose ID50 values range from 0.02 to 2511nM where DmTβH was inhibited in a dose-dependent manner at pH 7.6 and 25°C during a 30min of incubation. To understand the catalytic role of the TβH, a three dimensional structure of the TβH from Drosophila melanogaster was constructed by homology modeling using the Phyre2 web server with 100% confidence. The modeled three-dimensional structure of TβH was used to perform the docking study with AITs. This may give more insights to precise design of inhibitors for TβH to control insect's population.

• MeSH
• Drosophila melanogaster enzymologie   MeSH
• inhibitory enzymů chemie   MeSH
• katalytická doména MeSH
• konformace proteinů, beta-řetězec MeSH
• oxygenasy se smíšenou funkcí antagonisté a inhibitory   chemie   MeSH
• proteiny Drosophily antagonisté a inhibitory   chemie   MeSH
• sekvence aminokyselin MeSH
• simulace molekulární dynamiky MeSH
• simulace molekulového dockingu MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Structural analysis of the orientations of heme vinyl side chains was carried out using the published crystallographic data for different cytochromes P450. Torsional angles (tau, C(alpha)C(beta)-C(a)C(b)) show different distributions for the vinyls in positions 2 and 4. Whereas the orientation of 2-vinyls is rather restricted (tau between -120 degrees and -180 degrees ), the 4-vinyls have a much higher mobility over almost the entire conformational space. On the basis of the empirical correlation recently reported for peroxidases (M.P. Marzocchi, G. Smulevich, Relationship between heme vinyl conformation and the protein matrix in peroxidases, J. Raman Spectrosc. 34 (2003), 725-736), an attempt has been made to compare the observed vinyl orientations with the experimental frequencies of the vinyl stretching vibrational modes. The data for P450 proteins do not exactly match the peroxidase-derived function, although a qualitatively similar relationship is likely to exist. Differences between P450 forms suggest a variability in heme-region flexibility and in communication with the rest of enzyme.

• MeSH
• 5-monooxygenasa kafru chemie   MeSH
• bakteriální proteiny chemie   MeSH
• financování organizované MeSH
• hem chemie   MeSH
• izoenzymy chemie   MeSH
• konformace proteinů MeSH
• NADPH-cytochrom c-reduktasa MeSH
• oxygenasy se smíšenou funkcí chemie   MeSH
• Ramanova spektroskopie MeSH
• systém (enzymů) cytochromů P-450 chemie   MeSH