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Subunit Present (subunit + present)
Selected AbstractsHighly Enantioselective Organocatalytic syn - and anti -Aldol Reactions in Aqueous MediumADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Monika Raj Abstract We have synthesized chiral diamines that efficiently catalyze the syn - and anti -aldol reactions in aqueous medium with high diastereo- and enantioselectivities. The product, thus obtained, was further reduced selectively to give syn -configured 1,2,3-triol, an important subunit present in various monosaccharides and natural products such as (+)-boronolide. [source] THE , SUBUNITS OF PHYCOERYTHRIN FROM A RED ALGA: POSITION IN PHYCOBILISOMES AND SEQUENCE CHARACTERIZATIONJOURNAL OF PHYCOLOGY, Issue 1 2001Kirk E. Apt Aglaothamnion neglectum Feldman-Mazoyer has two , subunits, ,31 and ,33, that are associated with phycoerythrin in the light-harvesting phycobilisomes. We demonstrate that these subunits are spatially separated within the phycobilisome, with the ,31 subunit present at the distal end of phycobilisome rods and the ,33 subunit present on the proximal end. These subunits are thought to link phycoerythrin hexamers together in the rod substructure, serving a role analogous to that of linker polypeptides of cyanobacteria (although unlike the cyanobacterial linker polypeptides they are chromophorylated). The sequencing of tryptic polypeptides of the , subunits enabled us to prepare oligonucleotides encoding different regions of ,31. These oligonucleotides were used as primers to generate a probe for isolating a ,31 cDNA clone. Characterization of the cDNA clone predicts a polypeptide of 280 amino acids with a 42 amino acid presequence that is characteristic of a transit peptide, the peptide that targets proteins to chloroplasts of vascular plants. The ,31 subunit has 50% similarity to the previously characterized ,33 subunit but has no identifiable similarity to functionally related polypeptides present in cyanobacterial phycobilisomes or to any other polypeptides in the databases. A repeat of 95 amino acids is present in the red algal , subunit sequences, suggesting that these proteins were generated by a gene duplication followed by fusion of the duplicate sequences. [source] Mg2+ and memantine block of rat recombinant NMDA receptors containing chimeric NR2A/2D subunits expressed in Xenopus laevis oocytesTHE JOURNAL OF PHYSIOLOGY, Issue 1 2008David C. Wrighton N -methyl- d -aspartate receptors (NMDARs) display differences in their sensitivity to the channel blockers Mg2+ and memantine that are dependent on the identity of the NR2 subunit present in the receptor,channel complex. This study used two-electrode voltage-clamp recordings from Xenopus laevis oocytes expressing recombinant NMDARs to investigate the actions of Mg2+ and memantine at the two NMDARs displaying the largest differences in sensitivity to these blockers, namely NR1/NR2A and NR1/NR2D NMDARs. In addition, NR2A/2D chimeric subunits have been employed to examine the effects of pore-forming elements and ligand-binding domains (LBD) on the potency of the block produced by each of these inhibitors. Our results show that, as previously documented, NR2D-containing NMDARs are less sensitive to voltage-dependent Mg2+ block than their NR2A-containing counterparts. The reduced sensitivity is determined by the M1M2M3 membrane-associated regions, as replacing these regions in NR2A subunits with those found in NR2D subunits results in a ,10-fold reduction in Mg2+ potency. Intriguingly, replacing the NR2A LBD with that from NR2D subunits results in a ,2-fold increase in Mg2+ potency. Moreover, when responses mediated by NR1/NR2A NMDARs are evoked by the partial agonist homoquinolinate, rather than glutamate, Mg2+ also displays an increased potency. Memantine block of glutamate-evoked currents is most potent at NR1/NR2D NMDARs, but no differences are observed in its ability to inhibit NR2A-containing or NR2A/2D chimeric NMDARs. We suggest that the potency of block of NMDARs by Mg2+ is influenced not only by pore-forming regions but also the LBD and the resulting conformational changes that occur following agonist binding. [source] Inflammatory Pain Reduction In Rats By Local Treatment With oATP, A Selective Inhibitor Of P2X7 ATP ReceptorJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2001G Dell'Antonio Peptide neurotransmitters, as substance P or ATP, are released during inflammatiory processes by the nerve endings of sensory fibers. ATP is also released from the cytoplasm of damaged cells at the site of inflammation. It acts at the level of many P2X subtypes of purinoreceptors. The receptor for extracellular ATP named P2Z/P2X7 is selectively blocked by the periodate oxidized ATP (oATP). We have hypothesized that P2X subunits present on peripheral sensory nerve terminals, able to initiate a nociceptive signal, could be blocked by local treatment with oATP, so inducing pain relief. Male inbred Fisher rats weighing about 250 g were used. Unilateral inflammation into rat hind paw was induced by intraplantar injection of Freund's complete adjuvant (FCA). The following signs of inflammation, from 3 to 48 h after FCA injection, were detected: increased paw volume, increased paw temperature and hyperalgesia. The latter was evaluated using an algesiometric test wich measured the paw pressure threshold (PPT, expressed in g). We treated some rats, bearing paw inflammation by 12 h, with local injection of 56 ,M oATP. We showed a significant reduction of hyperalgesia in treated rats (PPT = 190 ± 2.3 in inflamed paw of oATP treated vs. PPT = 60 ± 1.6 in inflamed paw of untreated rats, at 60 min following oATP innoculation). We showed also that treatment with oATP was more efficient than treatment with diclofenac in reducing local inflammatory pain (PPT expressed as percentage of the maximum possible effect = 60 ± 0.5, at 120 min following intraplantar administration of oATP, vs. 25 ± 1.9 at the same time following intraplantar administration of diclofenac). The use of polyclonal antibody anti P2X7 receptor to perform immunohistochemical analysis of inflamed tissue, showed a reduction of receptor expression at the level of nerve endings in sections obtained from rat paw treated with oATP with respect to sections obtained from untreated rats. Such an effect was independent on the recruitment of immunocytes in inflamed tissue. Our results demonstrate that ATP exerts a key role in the pathophysiology of peripheral inflammation and that oATP may be effective in treating inflammatory pain. [source] | ||||||||||