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

Electrophoretic variation of the enzymes glucose phosphate isomerase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase and glutamate dehydrogenase (NADP-dependent) has been studied in the African murine malaria parasites Plasmodium berghei, P. yoelii, P. vinckei and P. chabaudi and their subspecies. Horizontal starch gel electrophoresis was used throughout. The number of isolates examined in each subspecies varied from 1 (P. y. nigeriensis) to 24 (P. c. chabaudi). Extensive enzyme variation was found among isolates of most of the subspecies from which more than two such isolates were available for study. It is clear that the phenomenon of enzyme polymorphism is of common occurrence among malaria parasites. With the exception of P. berghei and P. yoelii, of which all isolates share an identical electrophoretic form of lactate dehydrogenase, no enzyme forms are shared between any of the 4 species of murine plasmodia. By contrast, within each species common enzyme forms are shared among each of the subspecies. The subspecies are nevertheless, distinguished from each other by the electrophoretic forms of at least one enzyme. The distribution and reassortment of enzyme variation among isolates of a single subspecies is in accordance with the concept of malaria parasites as sexually reproducing organisms. The study of variation among parasites present in individual wild-caught rodent hosts demonstrates that natural malarial infections usually comprise genetically heterogeneous populations of parasites. Nevertheless, the number of genetically distinct types of parasite of any one species present in a single infected host appears to be small. Generally not more than 2 or 3 clones of parasite of distinct genetic constitution are present in a single infected animal.
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PMID:Studies on enzyme variation in the murine malaria parasites Plasmodium berghei, P. yoelii, P. vinckei and P. chabaudi by starch gel electrophoresis. 35 25

The multiplication of malaria parasites within red blood cells is energy dependent. Since these parasites lack a functional tricarboxylic acid cycle, the energy needs of the parasite are met by anaerobic glycolysis of exogenous glucose. High levels of glycolytic enzymes such as fructose-1,6-diphosphate aldolase, phosphoglycerate kinase and pyruvate kinase have been detected in infected erythrocytes. Here we report a 4-9 times increase in glucose phosphate isomerase (GPI) activity of infected erythrocytes over that of normal erythrocytes. This increase is of parasitic origin, as additional enzyme bands were observed in lysates of infected erythrocytes. The expression of GPI parallels parasite maturation and reaches a maximum at the trophozoite/schizont stage. Two distinct but closely related activity patterns consisting of 3-4 GPI isoenzymes (not shown in normal erythrocytes) with neutral to weakly acidic isoelectric points were observed in 6 P. falciparum isolates tested by isoelectric focusing. The purified P. falciparum GPI has an apparent size of 66 kDa. No size variation was observed in the 6 P. falciparum isolates studied. Furthermore, antiserum raised against this protein in BALB/c mice specifically inhibits parasite encoded GPI activity while no effect was observed on host enzyme activity.
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PMID:Identification and purification of glucose phosphate isomerase of Plasmodium falciparum. 143 56

185 isolates of Plasmodium vivax were collected from patients visiting the malaria clinic run by the National Malaria Eradication Programme, Delhi, India. Percoll gradient centrifugation was used to concentrate P. vivax parasites from 0.4 to 0.5 ml of blood collected by finger prick. The parasite concentrate from each isolate was electrophoretically analysed for lactate dehydrogenase (LDH), NADP-dependent glutamate dehydrogenase (GDH), glucose phosphate isomerase (GPI) and adenosine deaminase (ADA). Variations were observed in GPI, GDH and ADA systems. Four electrophoretic forms of GPI and 5 each of GDH and ADA were observed. Electrophoretic mobilities of the different isoenzymic forms in P. vivax were identical to those reported for P. falciparum, indicating that the 2 species cannot be differentiated on the basis of electrophoretic patterns of the 4 enzyme systems studied.
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PMID:Plasmodium vivax: enzyme polymorphism in isolates of Indian origin. 269 26

A new electrophoretic variant of glucose phosphate isomerase (GPI), which we now denote GPI-3, has been found in isolates of Plasmodium falciparum from 6 patients, all of whom acquired the infection in the same region (in or near Prachinburi province) of Thailand. In other regions, from which 453 isolates have been tested, only GPI-1 and/or GPI-2 have been found. Two isolates of P. malariae from patients at Kanchanaburi showed a band of GPI activity on cellulose acetate gels at a cathodal position quite distinct from that of any previously known GPI variants in other human malaria parasites. Thirty-nine isolates of P. vivax from 3 regions of Thailand have been examined for variants of GPI and lactate dehydrogenase (LDH). Three forms of GPI were found, corresponding approximately in band positions to GPI-1, 2 and 3 of P. falciparum. The position of the band of LDH activity in P. vivax was the same in all the isolates examined, and different from that of LDH-1 in P. falciparum.
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PMID:Electrophoretic variants of enzymes in isolates of Plasmodium falciparum, P. malariae and P. vivax from Thailand. 269 98

Proteins in malaria parasites (Plasmodium falciparum) isolated from a patient in Thailand before treatment, and after recrudescence of infection subsequent to mefloquine treatment, were compared by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) analysis. Nine 'pre-treatment' and six 'recrudescent' clones were studied. Variants of the enzyme glucose phosphate isomerase were also noted and mefloquine susceptibility of each clone was measured by in vitro tests. The 'pre-treatment' isolate was found to contain at least four genetically distinct clones, all sensitive to mefloquine, while the 'recrudescent' isolate contained at least two other types of clone, both showing increased tolerance to mefloquine. These two more tolerant types of clone differed from all the sensitive ones studied in regard to several different protein variants as shown by 2D-PAGE analysis. It is concluded that at least two (and probably more) genetically distinct clones of parasites with increased tolerance to mefloquine were present in the parasite population before mefloquine treatment was given, and were selected under mefloquine pressure.
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PMID:Polymorphism of proteins in malaria parasites following mefloquine treatment. 355 40

Three taxa of the malaria mosquito Anopheles balabacensis complex representing three geographical regions (Thailand, Peninsular Malaysia and Sabah) in Southeast Asia, were analysed for genetic variation at 15 gene-enzyme systems. The Sabah taxon was monomorphic for all the 15 gene-enzyme systems. Only two gene-enzyme systems (esterase and glucose phosphate isomerase) were variable in the Thailand and Peninsular Malaysia taxa. The average heterozygosity or gene diversity was 0.007 for the Thailand taxon and 0.028 for the Peninsular Malaysia (Perlis) taxon. There were no unique gene-enzyme markers in the three taxa studied. The average values of genetic identities (0.933-0.997) and genetic distances (0.003-0.069) indicate that these three taxa are of subspecific status.
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PMID:Biochemical genetic relationship in three taxa of the malaria mosquito Anopheles balabacensis complex. 664 Nov 78

The gene encoding dihydrofolate reductase-thymidylate synthase of the human malaria parasite, Plasmodium vivax, was isolated by polymerase chain reaction from genomic DNA and cloned. The sequences of the dihydrofolate reductase domain of 30 clinical isolates originating from various geographic areas were compared. Interstrain analysis revealed several genotypic variations, including short tandem repeat arrays which produced length polymorphism between different parasite isolates and point mutations in the putative dihydrofolate reductase active site cavity corresponding to those associated with pyrimethamine resistance in P. falciparum and rodent malaria parasites. Amino acid substitutions Ser-->Asn-117 and Ser-->Arg-58 were associated with decreased level of in vitro pyrimethamine sensitivity. These findings suggest that the P. vivax dihydrofolate reductase domain is characterized by polymorphism that has not been observed in P. falciparum and may explain the resistance of some P. vivax isolates to pyrimethamine. Nucleotide sequence data reported in this paper are available in the EMBL, GenBank and DDJB databases under the accession numbers X98123 (isolate ARI/Pakistan), AJ003050 (isolate CNC/Thailand), AJ003051 (isolate COU/unknown geographic origin), AJ003052 (isolate DUF/French Guiana), AJ003053 (isolate GRO/Madagascar), AJ003054 (isolate HRT/Comoros Islands), AJ003071 (isolate LFT/Cambodia), AJ003072 (isolate LGF/'India), AJ003073 (isolate MAN/Comoros Islands), AJ003074 (isolate MAT/Surinam), AJ003075 (isolate PHI/Djibouti), AJ003076 (isolate PIT/Madagascar), AJ003077 (isolate YTZ/Indonesia), AJ222630 (isolate Burma-1), AJ222631 (isolate Burma-151), AJ222632 (isolate Burma-5), AJ222633 (isolate Burma-6), AJ222634 (isolate Burma-98).
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PMID:Sequence variations in the Plasmodium vivax dihydrofolate reductase-thymidylate synthase gene and their relationship with pyrimethamine resistance. 965 31