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)

Human malaria infected erythrocytes show a dramatic increase in adenosine deaminase activity in vitro. Using recently developed culture techniques, adenosine deaminase-deficient human erythrocytes were infected in vitro with the major human pathogen Plasmodium falciparum. Adenosine deaminase activity was undetectable in the uninfected host red cells, but increased by 2-fold over normal levels in these cells with an 8% parasitemia. The enzyme in these cells appeared unique in that its activity was markedly elevated over that of other parasite purine enzymes, was not cross-reactive with antibody against human erythrocyte adenosine deaminase, and though inhibited competitively by deoxycoformycin was relatively insensitive to erythro-9-(2-hydroxy-3-nonyl) adenine. The use of adenosine deaminase-deficient erythrocytes for the in vitro cultivation of Plasmodium provides a unique system for the study of parasite enzyme and allows further insight into the purine metabolism of the intraerythrocytic malaria parasite.
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PMID:Human malaria parasite adenosine deaminase. Characterization in host enzyme-deficient erythrocyte culture. 636 11

Adenosine deaminase (ADA) activities in serum samples, erythrocytes, leukocytes and plasma hemoglobin concentrations were investigated in 50 patients with vivax malaria and compared with control group. ADA activity was determined by Bertholet reaction. Student's t-test and correlation analyses methods were used for statistical analyses. Serum ADA activity in patients with vivax malaria 49.20 +/- 29.02 IU/I, in control 21.15 +/- 8.04 IU/I (p = 0.005), erythrocyte ADA activity in patients 2.91 +/- 1.23 U/gr Hb, in control 1.65 +/- 0.59 U/gr (p = 0.001), leukocyte specific ADA activity in patients 26.23 +/- 20.21 U/mg protein, in control 25.84 +/- 9.19 U/gr Hb were determined (P > 0.05). Plasma hemoglobin concentration in patients 29.25 +/- 28.10 ml/dl, in control 9.80 +/- 13.14 mg/dl were also determined. There is no significant correlation among mentioned parameters. Erythrocyte purine salvage pathway is accelerated by Plasmodium to provide preformed purine source which can not be synthesized by Plasmodium to provide preformed purine source which can correlation between plasma hemoglobin concentration and serum ADA activity suggests that increased serum ADA activity may develop secondarily to the disease independently from the hemolyses. No higher ADA activity level than expected value of leukocytes may reflect immunosuppression of leukocytes.
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PMID:Serum erythrocyte and leukocyte adenosine deaminase activities in patients with vivax malaria in Turkey. 925 83

Adenosine deaminases (ADAs) from human, bovine, and Plasmodium falciparum sources were analyzed by kinetic isotope effects (KIEs) and shown to have distinct but related transition states. Human adenosine deaminase (HsADA) is present in most mammalian cells and is involved in B- and T-cell development. The ADA from Plasmodium falciparum (PfADA) is essential in this purine auxotroph, and its inhibition is expected to have therapeutic effects for malaria. Therefore, ADA is of continuing interest for inhibitor design. Stable structural mimics of ADA transition states are powerful inhibitors. Here we report the transition-state structures of PfADA, HsADA, and bovine ADA (BtADA) solved using competitive kinetic isotope effects (KIE) and density functional calculations. Adenines labeled at [6-13C], [6-15N], [6-13C, 6-15N], and [1-15N] were synthesized and enzymatically coupled with [1'-14C] ribose to give isotopically labeled adenosines as ADA substrates for KIE analysis. [6-13C], [6-15N], and [1-15N]adenosines reported intrinsic KIE values of (1.010, 1.011, 1.009), (1.005, 1.005, 1.002), and (1.004, 1.001, 0.995) for PfADA, HsADA, and BtADA, respectively. The differences in intrinsic KIEs reflect structural alterations in the transition states. The [1-15N] KIEs and computational modeling results indicate that PfADA, HsADA, and BtADA adopt early SNAr transition states, where N1 protonation is partial and the bond order to the attacking hydroxyl nucleophile is nearly complete. The key structural variation among PfADA, HsADA, and BtADA transition states lies in the degree of N1 protonation with the decreased bond lengths of 1.92, 1.55, and 1.28 A, respectively. Thus, PfADA has the earliest and BtADA has the most developed transition state. This conclusion is consistent with the 20-36-fold increase of kcat in comparing PfADA with HsADA and BtADA.
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PMID:Transition-state variation in human, bovine, and Plasmodium falciparum adenosine deaminases. 1753 4