Navegando por Palavras-chave "Periplaneta americana"

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    Cockroach allergens and asthma in Brazil: Identification of tropomyosin as a major allergen with potential cross-reactivity with mite and shrimp allergens
    (Mosby-year Book Inc, 1999-08-01) Santos, ABR; Chapman, M. D.; Aalberse, R. C.; Vailes, L. D.; Ferriani, VPL; Oliver, C.; Rizzo, M. C.; Naspitz, C. K.; Arruda, L. K.; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Netherlands Red Cross; Univ Virginia
    Background: Cockroaches produce several proteins that induce IgE antibody responses. Although cockroaches are abundant in warm and humid areas, sensitization to cockroach allergens has not been investigated in Brazil.Objective: the aims of this study were to investigate the frequency of cockroach allergy among patients with asthma, rhinitis, or both in Brazil and to identify American cockroach allergens.Methods: Skin tests using cockroach extracts were performed on children and young adults with asthma, rhinitis, or both. A Periplaneta americana complementary (c)DNA library was screened by using IgE antibodies from Brazilian patients allergic to cockroaches. Reactivity of an mAb directed to Dermatophagoides pteronyssinus tropomyosin against cockroach tissue was examined by immunofluorescence.Results: Cockroach allergy was present in 55% and 79% of the patients, as determined by using skin prick tests alone or combined prick and intradermal tests, respectively. Five cDNA clones reacted with IgE antibody and contained the same sequence. A representative clone (1300 bp), pa12, coded for a protein that reacted with 50% of the sera from patients allergic to cockroaches on plaque immunoassay and showed a high degree of homology to tropomyosins, particularly those from invertebrates. P americana tropomyosin showed 80%, 81%, and 82% sequence identity to tropomyosins from D pteronyssinus, D farinae, and shrimp, respectively, which have been previously defined as important allergens. An mAb directed against D pteronyssinus tropomyosin, which also recognizes shrimp tropomyosin, showed binding to cockroach striated muscle.Conclusion: Our results support the recommendation that cockroach extracts should be routinely used for the evaluation of patients with asthma, rhinitis, or both in Brazil. the identification of P americana tropomyosin as an important allergen Hill make it possible to investigate cross-reactivity among cockroaches, mites, and food derived from invertebrates.
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    Subsites of trypsin active site favor catalysis or substrate binding
    (Elsevier B.V., 2002-01-11) Marana, SR; Lopes, A. R.; Juliano, L.; Juliano, M. A.; Ferreira, C.; Terra, W. R.; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)
    Enzymes enhance chemical reaction rates by lowering the activation energy, the energy barrier of the reaction leading to products. This occurs because enzymes bind the high-energy intermediate of the reaction (the transition state) more strongly than the substrate. We studied details of this process by determining the substrate binding energy (DeltaG(g), calculated from K-m values) and the activation energy (DeltaG(T), determined from k(cat)/K-m values) for the trypsin-catalyzed hydrolysis of oligopeptides. Plots of DeltaG(T) versus DeltaG(g) for oligopeptides with 15 amino acid replacements at each of the positions P-1', P-1, and P-2 were straight lines, as predicted by a derived equation that relates DeltaG(T) and DeltaG(g). the data led to the conclusion that the trypsin active site has subsites that bind moieties of substrate and of transition state in characteristic ratios, whichever substrate is used. This was unexpected and means that each subsite characteristically favors substrate binding or catalysis. (C) 2002 Elsevier Science.