National Nuclear Energy Commission

About: National Nuclear Energy Commission is a government organization based out in Rio de Janeiro, Brazil. It is known for research contribution in the topics: Dosimetry & Laser. The organization has 3816 authors who have published 4694 publications receiving 59951 citations.

Detoxification of snake venom using ionizing radiation

Abstract: It is generally recognized that energy absorbed from ionizing radiation (gamma rays) can inactivate biological material in two ways. A direct effect occurs when the primary event, i. e., ionization, is produced in the molecule itself. This is the case when a compound is irradiated in dry state. When a compound is irradiated in a solution, the indirect effect joins the direct(9). Since water is the most abundant constituent of biological material, it is important to consider the species produced by excitation and ionization of water itself, and the reaction of these species with the target molecules of biological importance. This indirect effect results from the reactions among the studied molecules and the products of radiation interaction with water or other solvents. Highly reactive compounds, the so-called free radicals, which are formed undergo many reactions among themselves, with the dissolved gas, and with other molecules in the solution. With water, the excitation is less important than ionization which is followed within picoseconds by the formation of free hydroxyl radicals and hydrated electrons(2,4,16). Alexander & Hamilton(1) showed that irradiation of proteins has revealed damage to aminoacid side chains, production of new groups, splitting of peptide bonds and formation of intramolecular and intermolecular cross-links. With these results, it would be possible to use of ionizing radiation to change those protein molecules in order to improve some of their properties according to the necessity. On the other hand, it is recognized that venoms in general are poorly immunogenic, yet fairly toxic(15). This causes problems because serotherapy is the treatment of choice in snakebite envenomations, and horse antivenom availability is dependent upon immunogenicity.

Production and characterization of biologically active Ala-Ser-(His)6-Ile-Glu-Gly-Arg-human prolactin (tag-hPRL) secreted in the periplasmic space of Escherichia coli.

Abstract: Human prolactin (hPRL) cDNA was obtained by screening of a pituitary cDNA library with a synthetic 21-mer oligonucleotide and with rat PRL cDNA. For its expression, use was made of a vector, p3SN8, containing tac-promoter-controlled sequences for a bacterial cellulase leader joined to sequences coding for Ala-Ser, a chromatographic affinity site consisting of six histidines and a Factor Xa cleavage site. The hPRL cDNA was inserted at the 3' end of the cleavage-site sequences. Expression in Escherichia coli led to secretion in the periplasmic space of a fully bioactive hPRL variant constituting authentic hPRL with a peptide tag, i.e. Ala-Ser-(His)6-Ile-Glu-Gly-Arg, at its N-terminal. This tag-hPRL could be rapidly and efficiently purified by metal-chelate affinity chromatography. The correct processing and quality of tag-hPRL was monitored by SDS/PAGE, Western-blot analysis, immunoassay and Nb2-lymphoma-cell bioassay. Treatment with Factor Xa for tag removal was only partially successful. Periplasmic secretion of tag-hPRL of the order of 0.7 micrograms/ml per A600 unit and one-step purification indicate feasibility for tag-hPRL production for in vitro diagnostic and research applications. This is the first report describing periplasmic secretion of a bioactive form of hPRL.