Authors:M. S. Casare, P. Spencer, L. A. Campos, and N. Nascimento
Crotoxin is a 23 kDa neurotoxin from Crotalus durissus terrificus and is composed of a 9 kDa acidic subunit (crotapotin) and a 14 kDa basic subunit (phospholipase A2). Crotamine is 4882 Da, basic polypeptide with myotoxic activity. These toxins, when submitted to gamma-rays, in aqueous
solution, present structural modifications, preserving their immunogenic properties. In the present work, we investigated
some structural modifications on both crotoxin and crotamine after gamma-radiation using various doses, in the presence or
not of “scavenger” substances. Our results indicate that irradiation leads to progressive changes in the structure of the
toxin, which could explain the lower toxicity observed.
Authors:J. A. Baptista, P. J. Spencer, J. E. Oliveira, M. S. Casare, and N. Nascimento
In the present work, we investigated the immunological behavior of bothropstoxin-1, a K49 phospholipase from Bothrops jararacussu, and of ovalbumin before and after irradiation with 60Co g-rays. Isogenic mice were immunized with either native or irradiated proteins. The circulating antibodies were isotyped
and titrated by ELISA. Results indicate that irradiated proteins were immunogenic and the antibodies elicited by them were
able to recognize the native proteins in ELISA. Data also indicate that the irradiated protein induced higher titers of IgG2a
and IgG2b, suggesting that Th1 cells were predominantly involved in the immune response. Structural modifications of the proteins
were investigated by SDS-PAGE, mass spectrometry and size exclusion chromatography. According to our data, irradiation promoted
structural modifications on both proteins, characterized by higher molecular weight forms (aggregates and oligomers). When
analyzed by mass spectrometry, the irradiated bothropstoxin appeared in several oxidized forms. These results indicate that
irradiation of toxic proteins can promote significant modifications in their structures, but still retain many of the original
antigenic and immunological properties of native form.
Authors:J. Baptista, D. Vieira, A. Galisteo-Júnior, P. Caproni, M. Casare, H. de Andrade-Júnior, P. Spencer, and N. Nascimento
We investigated the immunological behavior of BTHX-1, before and after irradiation. SDS-PAGE showed that BTHX-1 irradiated
in the presence of NaNO3, had its structure preserved. Animals’ plasma immunized with native BTHX-1 had high IgG1 titers. The irradiated protein induced
high titers of IgG2b. When the toxin was irradiated with t-butanol, there was a slight decrease in the production of IgG2b.
Real-time PCR showed that both the IL-2 as for IL4 was more expression from the cells of the animals immunized with BTHX-1
irradiated. These results indicate that irradiation of proteins leads to significant structural modifications.
Authors:J. Baptista, D. Vieira, A. Galisteo Júnior, O. Higa, M. Casare, C. Yonamine, P. Caproni, L. Campos, H. de Andrade Júnior, P. Spencer, and N. Nascimento
In this work, the authors investigated the immunological behavior of bothropstoxin-I (BTHX-1), before and after irradiation
process, and also the influence of scavengers substances on protein alterations induced by free radical production. Structural
modifications were investigated by SDS-PAGE in reducing or non-reducing conditions. In vitro cytotoxicity assay was performed
to test average toxic activities of BTHX-I. BALB/c Isogenic mice were immunized with irradiated or non-irradiated (native)
forms of BTHX-I and antibody titers and isotypes were determined by ELISA method. Expression of murine cytokines was analyzed
by using expression data obtained by quantitative real-time PCR (qPCR) assays. The results indicate that irradiation of proteins
leads to significant structural modifications, and also changes the cytokines profile during immunization process, regarding
a suitable approach to new immunogenic production.