Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Through use of techniques for continuous erythrocyte culture and novel chromatographic procedures we have identified the major salvage pathways for metabolism of purine bases in P. falciparum infected human erythrocytes. The malaria parasitized erythrocyte (PRBC) differs from the unparasitized mature erythrocyte (RBC) in the following ways: PRBC primarily utilize hypoxanthine for synthesis of both adenylates and guanylates; PRBC incorporate the base guanine into guanylates at a higher rate than control RBC, PRBC do not appear to use adenine effectively due to an overwhelming competition for this base by the whole erythrocyte population; although PRBC cultures show an initial increase in [ATP] this change is interpreted to reflect a generalized RBC response to malaria infection and not a response restricted to PRBC. Our observations have identified a purine pathway involving adenylosuccinate (AMPs) present only in PRBC (HYP leads to IMP leads to AMPS leads to AMP). They also demonstrate the importance of guanylate synthesis to the malaria parasite. We have shown that the purine metabolism of unparasitized erythrocytes is perturbed during malaria infection, an effect reflected primarily by an increase in erythrocyte ATP. This increase in host erythrocyte ATP not only improves metabolic conditions for parasite growth but also places a demand on available purine resources that has implications for the severe disruption of normal erythrocyte function.
 ...
PMID:Purine metabolism during continuous erythrocyte culture of human malaria parasites (P. falciparum). 702 71

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is the key enzyme in purine base salvage in humans and in purine auxotrophs, including Plasmodium falciparum, the leading cause of malaria. Hydrogen/deuterium (H/D) exchange into amide bonds, quantitated by on-line HPLC and mass spectrometry, has been used to compare the dynamic and conformational properties of human HGPRT alone, the HGPRT-GMP-Mg(2+) complex, the HGPRT-IMP-MgPPi <==> HGPRT-Hx-MgPRPP equilibrating mixture, and the transition-state analogue complex HGPRT-ImmGP-MgPPi. The rate and extent of H/D exchange of 26 peptic peptides, spanning 91% of the primary structure, have been monitored. Human HGPRT has 207 amide H/D exchange sites. After 1 h in D2O, HGPRT alone exchanges 160, HGPRT-GMP-Mg(2+) exchanges 154, the equilibrium complex exchanges 139, and the transition-state analogue complex exchanges 126 of these amide protons. H/D exchange rates are correlated with structure for peptides in (1) catalytic site loops, (2) a connected peptide of the subunit interface of the tetramer, and (3) a loop buried in the catalytic site. Structural properties related to H/D exchange are defined from crystallographic studies of the HGPRT-GMP-Mg(2+) and HGPRT-ImmGP-MgPPi complexes. Transition-state analogue binding strengthens the interaction between subunits and tightens the catalytic site loops. The solvent exchange dynamics in specific peptides correlates with hydrogen bond patterns, solvent access, crystallographic B-factors, and ligand exchange rates. Solvent exchange reveals loop dynamics in the free enzyme, Michaelis complexes, and the complex with the bound transition-state analogue. Proton transfer paths, rather than dynamic motion, are required to explain exchange into a buried catalytic site peptide in the complex with the bound transition-state analogue.
 ...
PMID:A transition-state analogue reduces protein dynamics in hypoxanthine-guanine phosphoribosyltransferase. 1143 73

In the absence of the de novo purine nucleotide biosynthetic pathway in parasitic protozoa, purine salvage is of primary importance for parasite survival. Enzymes of the salvage pathway are, therefore, good targets for anti-parasitic drugs. Adenylosuccinate synthetase (AdSS), catalysing the first committed step in the synthesis of AMP from IMP, is a potential target for anti-protozoal chemotherapy. We report here the crystal structure of adenylosuccinate synthetase from the malaria parasite, Plasmodium falciparum, complexed to 6-phosphoryl IMP, GDP, Mg2+ and the aspartate analogue, hadacidin at 2 A resolution. The overall architecture of P. falciparum AdSS (PfAdSS) is similar to the known structures from Escherichia coli, mouse and plants. Differences in substrate interactions seen in this structure provide a plausible explanation for the kinetic differences between PfAdSS and the enzyme from other species. Additional hydrogen bonding interactions of the protein with GDP may account for the ordered binding of substrates to the enzyme. The dimer interface of PfAdSS is also different, with a pronounced excess of positively charged residues. Differences highlighted here provide a basis for the design of species-specific inhibitors of the enzyme.
 ...
PMID:Crystal structure of fully ligated adenylosuccinate synthetase from Plasmodium falciparum. 1472 41

Plasmodium falciparum, the causative agent of the fatal form of malaria, synthesizes GMP primarily from IMP and, hence, needs active GMPS (GMP synthetase) for its survival. GMPS, a G-type amidotransferase, catalyses the amination of XMP to GMP with the reaction occurring in two domains, the GAT (glutamine amidotransferase) and ATPPase (ATP pyrophosphatase). The GAT domain hydrolyses glutamine to glutamate and ammonia, while the ATPPase domain catalyses the formation of the intermediate AMP-XMP from ATP and XMP. Co-ordination of activity across the two domains, achieved through channelling of ammonia from GAT to the effector domain, is the hallmark of amidotransferases. Our studies aimed at understanding the kinetic mechanism of PfGMPS (Plasmodium falciparum GMPS) indicated steady-state ordered binding of ATP followed by XMP to the ATPPase domain with glutamine binding in a random manner to the GAT domain. We attribute the irreversible, Ping Pong step seen in initial velocity kinetics to the release of glutamate before the attack of the adenyl-XMP intermediate by ammonia. Specific aspects of the overall kinetic mechanism of PfGMPS are different from that reported for the human and Escherichia coli enzymes. Unlike human GMPS, absence of tight co-ordination of activity across the two domains was evident in the parasite enzyme. Variations seen in the inhibition by nucleosides and nucleotide analogues between human GMPS and PfGMPS highlighted differences in ligand specificity that could serve as a basis for the design of specific inhibitors. The present study represents the first report on recombinant His-tagged GMPS from parasitic protozoa.
 ...
PMID:Kinetic and biochemical characterization of Plasmodium falciparum GMP synthetase. 1786 38

12B75, 274150; Abacavir sulfate/lamivudine, Abatacept, Ad2/HIF-1alpha, Adalimumab, Adefovir, Adefovir dipivoxil, AGN-201904-Z, AIDSVAX, Albinterferon alfa-2b, Alemtuzumab, Aliskiren fumarate, Alvimopan hydrate, Amlodipine besylate/atorvastatin calcium, Amlodipine besylate/Olmesartan medoxomil, Ammonium tetrathiomolybdate, Amodiaquine, Apaziquone, Aprepitant, Arsenic trioxide, Artesunate/Amodiaquine, Ascorbic acid, Atazanavir sulfate, Atazanavir/ritonavir, Atomoxetine hydrochloride, Atrigel-Leuprolide, Axitinib; Bevacizumab, Binodenoson, Bortezomib, Bovine lactoferrin; Calcipotriol/betamethasone dipropionate, Carisbamate, Certolizumab pegol, Ciclesonide, Conivaptan hydrochloride, CP-690550, CP-751871, Cypher; Dapivirine, Darbepoetin alfa, Darunavir, Dasatinib, del-1 Genemedicine, Denosumab, Desloratadine, Dexlansoprazole, DiabeCell, Drospirenone/ethinylestradiol, DTaP-HepB-IPV, Duloxetine hydrochloride, Dutasteride; Eculizumab, Eldecalcitol, Eletriptan, Emtricitabine, Entecavir, Eritoran tetrasodium, Ertapenem sodium, Escitalopram oxalate, Eslicarbazepine acetate, Esomeprazole magnesium, Estradiol acetate, Eszopiclone, ETEC vaccine, Etoricoxib, Exenatide, Ezetimibe; Fluticasone furoate, Fosmidomycin, Fosmidomycin/clindamycin; Glutamine; Heat Shock Protein 10, Hepatitis B hyperimmunoglobulin, HIV vaccine, Hochuekki-to, Human Albumin, Human papillomavirus vaccine; Immune globulin subcutaneous [human], IMP-321, Interferon omega, ISIS-301012, Istaroxime; Japanese encephalitis virus vaccine; Latanoprost/timolol maleate, Lenalidomide, Linaclotide acetate, Lumiracoxib, LY-517717; Malaria vaccine, MAS-063D, Meningitis B vaccine, Mepolizumab, Methylnaltrexone bromide, Micafungin sodium, MK-0822A, Morphine glucuronide, Morphine hydrochloride, Mycophenolic acid sodium salt; Natalizumab, Nesiritide, Norelgestromin/ethinyl estradiol, NT-201; Oblimersen sodium, Olmesartan medoxomil, Olmesartan medoxomil/hydrochlorothiazide, Omalizumab, Otamixaban; Paclitaxel nanoparticles, Panitumumab, Panobinostat, Parathyroid hormone (human recombinant), Parecoxib sodium, Pegfilgrastim, Peginterferon alfa-2a, Peginterferon alfa-2b, Pegvisomant, PI-88, Pimecrolimus, Pneumococcal 7-valent conjugate vaccine, Pneumococcal 9-valent conjugate vaccine, Pneumococcal conjugate vaccine, Poloxamer-188, Prasugrel, Pregabalin, Prulifloxacin; R-109339, Ramipril/amlodipine, Ranolazine, Rasburicase, rHA influenza vaccine, Ro-50-3821, Rosuvastatin calcium, Rotavirus vaccine, Rotigotine, Ruboxistaurin mesilate hydrate; Satavaptan, SC-75416, Solifenacin succinate, Sorafenib, Sugammadex sodium, Sunitinib malate, Synthetic conjugated estrogens B; Tadalafil, Talnetant, Taxus, Tegaserod maleate, Telbivudine, Temsirolimus, Tenofovir disoproxil fumarate, Tetomilast, Tiotropium bromide, Tipifarnib, Tofimilast, Tremelimumab, Trimethoprim; Udenafil, Urocortin 2; Valdecoxib, Vernakalant hydrochloride; XP-828L.
 ...
PMID:Gateways to clinical trials. 1798 11