Abstract:
:The codon for serine residue 108 of the Plasmodium falciparum dihydrofolate reductase gene was replaced with those for the other 19 amino acids. Except for the Lys108 mutant, which was not expressed, all other substitutions yielded DHFR mutants which were expressed in Escherichia coli as inactive inclusion bodies. Nine of the mutants--Asn108, Thr108, Gly108, Ala108, Gln108, Cys108, Val108, Leu108, and Met108--yielded active DHFR upon refolding of the protein from the inclusion bodies. The remaining mutants--IIe108, Arg108, Pro108, Asp108, His108, Tyr108, Phe108, Trp108, and Glu108--did not exhibit detectable DHFR activity on refolding. The Asn108 mutant had almost unperturbed kinetic parameters but conferred resistance to pyrimethamine and cycloguanil; other active mutants showed poorer DHFR activity. We purified and characterized four mutants which produced highest DHFR activity, i.e., the Gln108, Gly108, Cys108, and Ala108 mutants. These mutant enzymes had kcat/K(m) values ranging from 7 to 22% of the wild-type enzyme. While DHFRs from Gly108, Cys108, and Ala108 mutants were as susceptible to pyrimethamine and cycloguanil as the wild type, the Gln108 mutation conferred high resistance to both inhibitors. Our data suggest that residue 108 is important for antifolate binding, and that the Ser108 to Asn108 mutation was selected in nature because of (i) the need for only a single base change, (ii) its good activity, and (iii) its resistance to antifolates.
journal_name
Exp Parasitoljournal_title
Experimental parasitologyauthors
Sirawaraporn W,Yongkiettrakul S,Sirawaraporn R,Yuthavong Y,Santi DVdoi
10.1006/expr.1997.4221subject
Has Abstractpub_date
1997-11-01 00:00:00pages
245-52issue
3eissn
0014-4894issn
1090-2449pii
S0014-4894(97)94221-1journal_volume
87pub_type
杂志文章abstract::The release of beta-glucuronidase and lysozyme from human polymorphonuclear leukocytes (PMN) engaged in phagocytosis and lysis of Trypanosoma cruzi epimastigotes was studied in the presence or absence of chagasic serum. Lysosomal enzyme release was enhanced when parasites were sensitized with serum from a chronic Chag...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(83)90069-3
更新日期:1983-10-01 00:00:00
abstract::The Plasmodium vivax merozoite surface protein-1 (PvMSP-1) has been considered a candidate for a malaria vaccine against erythrocytic stages. PvMSP-1 is immunogenic during natural infections and exhibits antigenic polymorphism. The extent of genetic polymorphism in a region between the so-called interspecies conserved...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1006/expr.2000.4534
更新日期:2000-07-01 00:00:00
abstract::Extramedullar proliferation of eosinophil granulocytes can be induced in mice chronically infected with Schistosoma mansoni, by intraperitoneal implants of glass coverslips. Immature eosinophils are located in discrete foci on glass implants; they are not correlated with the eosinophil population of the peritoneal cav...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(86)90041-x
更新日期:1986-12-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1006/expr.1997.4148
更新日期:1997-03-01 00:00:00
abstract::Trichomonas vaginalis is a human urogenital pathogen that causes trichomoniasis, the most common nonviral, parasitic sexually transmitted infection in the world. At present, little is known regarding the degree of strain variability of T. vaginalis. A classification method for T. vaginalis strains would be a useful to...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2015.10.011
更新日期:2015-12-01 00:00:00
abstract::Though parasite cyclophilins are promising new drug targets, Eimeria tenella cyclophilins have not been characterized yet. Here, we describe an 89kDa cyclophilin, designated EtCYP89. It is expressed throughout the developmental cycle of E. tenella, both in the intracellular stages in chicken and in extracellular sporu...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2007.07.013
更新日期:2008-02-01 00:00:00
abstract::Among the wide variety of clinicopathological manifestations of intestinal amebiasis, amebomas occur rarely and their pathogenesis is not well understood. When cholesterol-fed, 2- to 4-week-old guinea pigs were infected intracecally with a virulent, monoaxenic strain of Entamoeba histolytica, gross and histologically ...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(92)90151-y
更新日期:1992-05-01 00:00:00
abstract::Leishmaniasis, a neglected tropical disease (NTD) causes major health problems in the tropical and subtropical world. Most of the antileishmanial modern therapies with different formulations of pentavalent antimonials, Miltefosine, Amphotericin B etc. are not satisfactory in recent times due to high toxicity to the ho...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2014.08.009
更新日期:2014-11-01 00:00:00
abstract::This study presents the first genetic characterization of five Trypanosoma rangeli isolates from Minas Gerais, in the southeast of Brazil and their comparison with Colombian populations by minicircle classification, RAPD-PCR and LSSP-PCR analyses. Our results demonstrated a homogenous T. rangeli population circulating...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2007.03.007
更新日期:2007-09-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2016.10.007
更新日期:2016-12-01 00:00:00
abstract::Leishmaniasis are globally widespread parasitic diseases which often leads to death if left untreated. Currently available drugs present different drawbacks, so there is an urgent need to develop new, safe and cost-effective drugs against leishmaniasis. In this study we tested a small library of trans-stilbene and ter...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2016.03.007
更新日期:2016-07-01 00:00:00
abstract::This study investigated the genetic characteristics of Toxoplasma gondii samples collected from 62 patients with toxoplasmosis in Sao Paulo State, Brazil. DNA samples were isolated from blood, cerebrospinal fluid and amniotic fluids of 25 patients with cerebral toxoplasmosis and AIDS, two patients with acute toxoplasm...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2011.06.002
更新日期:2011-10-01 00:00:00
abstract::Twenty-one Trypanosoma cruzi stocks isolated from Triatoma infestans and humans of the Chilean Andean highlands were studied at the genotypic level by schizodeme and molecular karyotype analyses, which allowed a clear distinction of the parasites from those hosts. A phenotypical characterization was performed by prote...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1006/expr.1995.1100
更新日期:1995-08-01 00:00:00
abstract::Serine proteases have been identified as important molecules that are involved in many parasitic infections, and these molecules have also been suggested to play important roles in Trichinella spiralis infections. In the present study, the antigenic serine protease gene Ts-ADSp-7, which was screened from a cDNA librar...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2018.09.009
更新日期:2018-12-01 00:00:00
abstract::High-throughput drug screening methods against the intracellular stage of Leishmania have been facilitated by the development of in vitro models of infection. The use of cell lines rather than primary cells facilitates these methods. Peripheral blood mononuclear cell (PBMC) derived macrophages and THP-1 cells were inf...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2010.06.007
更新日期:2010-12-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2005.12.006
更新日期:2006-06-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2010.04.018
更新日期:2010-10-01 00:00:00
abstract::The aim of this study was to analyze the antioxidant status and oxidative profile in serum and liver of rats experimentally infected with Fasciola hepatica and its relationship with pathological findings. Twenty-four rats were divided into two groups: group A consisted of 12 healthy rats and group B of 12 rats infecte...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2015.08.008
更新日期:2015-12-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2012.01.009
更新日期:2012-04-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2011.01.011
更新日期:2011-04-01 00:00:00
abstract::The sequential changes in the histology in scabietic lesions were investigated for hosts (rabbits) during sensitization and reinfestation with Sarcoptes scabiei. Experimentally infested naive hosts developed heavy scabies infestations but 65% of the hosts showed induced immunity (resistance) to reinfestation. All host...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1006/expr.1994.1005
更新日期:1994-02-01 00:00:00
abstract::An active Trypanosoma cruzi transmission cycle maintained by wild rodents in the Andean valleys of Cochabamba Bolivia is described. Wild and domestic Triatoma infestans with 60% infection with T. cruzi were found and was evidenced in 47.5% (rodents) and 26.7% (marsupial) by parasitological and/or serologycal methods. ...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2006.04.010
更新日期:2006-12-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(90)90007-y
更新日期:1990-07-01 00:00:00
abstract::The possible involvement of protein kinase C and Ca2+ metabolism in the proteolytic enzyme release from schistosome cercariae was studied. Cercariae were placed in dechlorinated tap water containing 0.37 mM calcium in the small glass petri dish and exposed to the stimuli (linoleic acid, phorbol esters, and Ca2+ ionoph...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(91)90151-l
更新日期:1991-04-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(89)90009-x
更新日期:1989-01-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/0014-4894(90)90026-9
更新日期:1990-08-01 00:00:00
abstract::An NADP-linked glutamate dehydrogenase (EC 1.4.1.4) was found in the soluble fraction of Trichomonas vaginalis. Its molecular weight was about 230,000 (gel filtration). The enzyme, partially purified by diafiltration and hydroxyapatite column chromatography, was heat stable (1 hr at 57 C). It catalyzed both the aminat...
journal_title:Experimental parasitology
pub_type: 杂志文章
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更新日期:1988-10-01 00:00:00
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journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2012.09.018
更新日期:2012-12-01 00:00:00
abstract::The differential effect of fox and pig bile and its corresponding low molecular weight fraction (LMW) was investigated on the in vitro invasion of MDCK-AA7 epithelial cell monolayers by Trichinella spiralis muscle larvae. Seven invasion experiments were performed and a total of 274 cell monolayers were examined. Fox a...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2010.05.013
更新日期:2010-12-01 00:00:00
abstract::Complex life cycle parasites can manipulate the behavior of intermediate hosts in order to reduce their fitness and increase the chance of completing life cycle. In order to understand the effects of the trematode parasites of the genus Clinostomum on host fish Loricariichthys platymetopon, a filmed experiment was car...
journal_title:Experimental parasitology
pub_type: 杂志文章
doi:10.1016/j.exppara.2020.107916
更新日期:2020-09-01 00:00:00