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William L. Smith - One of the best experts on this subject based on the ideXlab platform.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123-129 and residues 510-515. In cases where one monomer is fully occupied with an NSAID and the partner monomer is incompletely occupied, an alternate conformation of the loop involving residues 123-129 is seen in the partially occupied monomer. We propose, on the basis of this observation and previous cross-linking studies, that cross-talk between monomers involves this mobile 123-129 loop, which is located at the dimer interface. In ovine PGHS-1 crystallized in the absence of an NSAID, there is an alternative route for substrate entry into the COX site different than the well-known route through the membrane binding domain.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123−129 and residues 510−515. In cases where one monomer is fully o...
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selective inhibition of prostaglandin endoperoxide synthase 1 Cyclooxygenase 1 by valerylsalicylic acid
Archives of Biochemistry and Biophysics, 1995Co-Authors: D K Bhattacharyya, M Lecomte, J Dunn, D J Morgans, William L. SmithAbstract:Aspirin causes a time-dependent inhibition of prostaglandin endoperoxide H synthases (PGHS)-1 and -2 by acetylating active site serines present in both isozymes. In the case of PGHS-1, aspirin acetylation blocks Cyclooxygenase activity, apparently by preventing arachidonate binding to the Cyclooxygenase active site. With PGHS-2, acetylation does not block substrate binding but rather alters the enzyme in such a way that the acetylated form of PGHS-2 produces 15R-hydroxy-eicosatetraenoic acid (15R-HETE) instead of the usual prostaglandin endoperoxide product. Based on these differences between PGHS-1 and PGHS-2, we reasoned that a salicylate ester containing an acyl group somewhat larger than the acetyl group of aspirin might be a selective inhibitor of PGHS-2. Accordingly, we prepared and tested eight different acyl salicylates as inhibitors of human (h) PGHS-1 and -2 expressed transiently in cos-1 cells. Valeryl(pentanoyl)salicylate (VSA) was the only compound in this series which showed isozyme selectivity, and, surprisingly, VSA inhibited hPGHS-1 much more effectively than hPGHS-2. Inhibition of hPGHS-1 by VSA was time-dependent. VSA also inhibited ovine PGHS-1 but did not inhibit the S530A mutant of ovine PGHS-1. This latter mutant, which lacks the active site serine hydroxyl group, is also refractory to inhibition by acetylsalicylate. Thus, we conclude that VSA acylates the active site serine of PGHS-1, VSA inhibited prostanoid synthesis by serum-starved murine NIH 3T3 cells which express only PGHS-1; in contrast, VSA caused only partial inhibition of prostanoid synthesis by serum-stimulated 3T3 cells which express both PGHS isozymes. Our results establish that VSA can be used as a reasonably selective inhibitor of PGHS-1.
Ranjinder S Sidhu - One of the best experts on this subject based on the ideXlab platform.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123−129 and residues 510−515. In cases where one monomer is fully o...
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123-129 and residues 510-515. In cases where one monomer is fully occupied with an NSAID and the partner monomer is incompletely occupied, an alternate conformation of the loop involving residues 123-129 is seen in the partially occupied monomer. We propose, on the basis of this observation and previous cross-linking studies, that cross-talk between monomers involves this mobile 123-129 loop, which is located at the dimer interface. In ovine PGHS-1 crystallized in the absence of an NSAID, there is an alternative route for substrate entry into the COX site different than the well-known route through the membrane binding domain.
Jullia Y Lee - One of the best experts on this subject based on the ideXlab platform.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123-129 and residues 510-515. In cases where one monomer is fully occupied with an NSAID and the partner monomer is incompletely occupied, an alternate conformation of the loop involving residues 123-129 is seen in the partially occupied monomer. We propose, on the basis of this observation and previous cross-linking studies, that cross-talk between monomers involves this mobile 123-129 loop, which is located at the dimer interface. In ovine PGHS-1 crystallized in the absence of an NSAID, there is an alternative route for substrate entry into the COX site different than the well-known route through the membrane binding domain.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123−129 and residues 510−515. In cases where one monomer is fully o...
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coxibs interfere with the action of aspirin by binding tightly to one monomer of Cyclooxygenase 1
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Gilad Rimo, Ranjinde S Sidhu, Adam D Lauve, Jullia Y Lee, Naraya Sharma, Chong Yua, Rya A Friele, Raymond C Trievel, Enedic R LucchesiAbstract:Pain associated with inflammation involves prostaglandins synthesized from arachidonic acid (AA) through Cyclooxygenase-2 (COX-2) pathways while thromboxane A2 formed by platelets from AA via Cyclooxygenase-1 (COX-1) mediates thrombosis. COX-1 and COX-2 are both targets of nonselective nonsteroidal antiinflammatory drugs (nsNSAIDs) including aspirin whereas COX-2 activity is preferentially blocked by COX-2 inhibitors called coxibs. COXs are homodimers composed of identical subunits, but we have shown that only one subunit is active at a time during catalysis; moreover, many nsNSAIDS bind to a single subunit of a COX dimer to inhibit the COX activity of the entire dimer. Here, we report the surprising observation that celecoxib and other coxibs bind tightly to a subunit of COX-1. Although celecoxib binding to one monomer of COX-1 does not affect the normal catalytic processing of AA by the second, partner subunit, celecoxib does interfere with the inhibition of COX-1 by aspirin in vitro. X-ray crystallographic results obtained with a celecoxib/COX-1 complex show how celecoxib can bind to one of the two available COX sites of the COX-1 dimer. Finally, we find that administration of celecoxib to dogs interferes with the ability of a low dose of aspirin to inhibit AA-induced ex vivo platelet aggregation. COX-2 inhibitors such as celecoxib are widely used for pain relief. Because coxibs exhibit cardiovascular side effects, they are often prescribed in combination with low-dose aspirin to prevent thrombosis. Our studies predict that the cardioprotective effect of low-dose aspirin on COX-1 may be blunted when taken with coxibs.
Chong Yuan - One of the best experts on this subject based on the ideXlab platform.
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123−129 and residues 510−515. In cases where one monomer is fully o...
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comparison of Cyclooxygenase 1 crystal structures cross talk between monomers comprising Cyclooxygenase 1 homodimers
Biochemistry, 2010Co-Authors: Ranjinder S Sidhu, Jullia Y Lee, Chong Yuan, William L. SmithAbstract:Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called Cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123-129 and residues 510-515. In cases where one monomer is fully occupied with an NSAID and the partner monomer is incompletely occupied, an alternate conformation of the loop involving residues 123-129 is seen in the partially occupied monomer. We propose, on the basis of this observation and previous cross-linking studies, that cross-talk between monomers involves this mobile 123-129 loop, which is located at the dimer interface. In ovine PGHS-1 crystallized in the absence of an NSAID, there is an alternative route for substrate entry into the COX site different than the well-known route through the membrane binding domain.
Shinichi Kawai - One of the best experts on this subject based on the ideXlab platform.
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Cyclooxygenase 1 and Cyclooxygenase 2 selectivity of non steroidal anti inflammatory drugs investigation using human peripheral monocytes
Journal of Pharmacy and Pharmacology, 2010Co-Authors: Miyako Kato, Shinichi Nishida, Hidero Kitasato, Natsue Sakata, Shinichi KawaiAbstract:Since the pharmacological profiles of various non-steroidal anti-inflammatory drugs (NSAIDs) might depend on their differing selectivity for Cyclooxygenase 1 (COX-1) and 2 (COX-2), we developed a new screening method using human peripheral monocytes. Monocytes from healthy volunteers were separated, and the cells were incubated with or without lipopolysaccharide (LPS). Monocytes without LPS stimulation exclusively expressed COX-1 on Western blotting analysis, whereas LPS stimulation induced COX-2 expression. Unstimulated monocytes (COX-1) and LPS-stimulated monocytes (COX-2) were then used to determinethe COX selectivity of various NSAIDs. The respective mean IC50 values for COX-1 and COX-2 IC50 (microM), and the COX-1/COX-2 ratio of each NSAID were as follows: celecoxib, 82, 6.8, 12; diclofenac, 0.076, 0.026, 2.9; etodolac, > 100, 53, > 1.9; ibuprofen, 12, 80, 0.15; indometacin, 0.0090, 0.31, 0.029; meloxicam, 37, 6.1, 6.1; 6-MNA (the active metabolite of nabumetone), 149, 230, 0.65; NS-398, 125, 5.6, 22; piroxicam, 47, 25, 1.9; rofecoxib, > 100, 25, > 4.0; S-2474, > 100, 8.9, > 11; SC-560, 0.0048, 1.4, 0.0034. The percentage inhibition of COX-1 activity at the IC50 of COX-2 also showed a wide variation among these NSAIDs. The bioassay system using human monocytes to assess the inhibitory effects of various NSAIDs on COX-1 and COX-2 may become a clinically useful screening method.
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comparison of Cyclooxygenase 1 and 2 inhibitory activities of various nonsteroidal anti inflammatory drugs using human platelets and synovial cells
European Journal of Pharmacology, 1998Co-Authors: Shinichi Kawai, Renzo Okamoto, Tomihisa Koshino, Shinichi Nishida, Miyako Kato, Yasuko Furumaya, Yutaka MizushimaAbstract:Recent studies have shown that Cyclooxygenase exists in two isozyme forms. Since differences in the pharmacological profiles of nonsteroidal anti-inflammatory drugs (NSAIDs) might be accounted for by varying degrees of selectivity for these isozymes, Cyclooxygenase-1 and -2, the relative potency of various NSAIDs in inhibiting their activities was examined in intact human cells. We used human platelets Cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell Cyclooxygenase-2 for measuring Cyclooxygenase selectivity. The presence of the enzymes was confirmed by immunoblotting and immunoprecipitation analysis, and by the reverse transcriptase-polymerase chain reaction. Mean IC50 values (microM) for human platelet Cyclooxygenase-1 and interleukin-1beta-stimulated human synovial cell Cyclooxygenase-2 and Cyclooxygenase-1/-2 IC50 ratio of various NSAIDs were as follows: aspirin, 3.2, 26, 0.12; diclofenac, 0.037, 0.00097, 38; etodolac, 122, 0.68, 179; ibuprofen, 3.0, 3.5, 0.86; indomethacin, 0.013, 0.044, 0.30; loxoprofen (active metabolite), 0.38, 0.12, 3.2; NS-398, 12, 0.0095, 1263; oxaprozin, 2.2, 36, 0.061; zaltoprofen, 1.3, 0.34, 3.8; respectively. Our bioassay system employing intact human cells to assess the Cyclooxygenase selectivity of NSAIDs may provide clinically useful information.
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aceclofenac blocks prostaglandin e2 production following its intracellular conversion into Cyclooxygenase inhibitors
European Journal of Pharmacology, 1997Co-Authors: Ryuta Yamazaki, Shinichi Kawai, Takeshi Matsuzaki, Shusuke Hashimoto, Teruo Yokokura, Renzo Okamoto, Tomihisa Koshino, Norimasa Kaneda, Yutaka MizushimaAbstract:Aceclofenac, 2-[(2,6-dichlorophenyl) amino] phenylacetoxyacetic acid, is a novel non-steroidal anti-inflammatory drug. We investigated the effects of aceclofenac on prostaglandin E2 production by several kinds of human cells. Aceclofenac inhibited interleukin-1β-induced prostaglandin E2 production by human rheumatoid synovial cells, but had no inhibitory effect on Cyclooxygenase-1 or Cyclooxygenase-2 activities by itself. We also observed that part of the aceclofenac was converted into diclofenac, the Cyclooxygenase-1 and Cyclooxygenase-2 inhibitor, when aceclofenac was incubated with human rheumatoid synovial cells. Aceclofenac was also converted into diclofenac and 4′-hydroxy diclofenac by human polymorphonuclear leukocytes and monocytes. 4′-Hydroxy diclofenac suppressed prostaglandin E2 production specifically by blocking Cyclooxygenase-2 activity. These findings suggested that aceclofenac can be metabolized to Cyclooxygenase inhibitors (diclofenac and/or 4′-hydroxy diclofenac) by these inflammatory cells. Although detailed examinations in non-inflammatory cells remain to be studied, we concluded that aceclofenac is shown to be a new type of non-steroidal anti-inflammatory drug which is intracellulary converted into active metabolites that inhibit the prostaglandin E2 production.
