Resumo

RUEDA DE ARVELO, Emma; RAMIS, Catalina  e  TRIANA ALONSO, Francisco. Ribonuclease Activity in Latex from Calotropis procera (Aiton) W.T. Aiton and Pedilanthus tithymaloides (L.) Poit. Rev. Fac. Nac. Agron. Medellín [online]. 2013, vol.66, n.2, pp.7057-7070. ISSN 0304-2847.

Ribonuclease enzymes (RNase) have been used effectively in the treatment of certain cancers and other properties that may be applicable in biotechnology. In order to identify the RNase activity in the latex of Calotropis procera and Pedilanthus tithymaloides, tropical plants samples were collected from adult plants located in the North State of Aragua, Venezuela. Soluble proteins were extracted with 50 mM sodium acetate pH 5 (16 mL/mg latex) and poliisoprenoide portion was removed by centrifugation at 16,000 x g for 15 min. RNase activity was estimated using a technique that involves the application of reaction mixture aliquots on polyacrylamide-urea gels and separated by electrophoresis. Substrate degradation was quantified by densitometry. Various substrates were tested (tRNAtotal, tRNA^phe and mRNA transcribed in vitro from plasmid DNA). The latex from both species showed RNase activity, with initial specific activities of 1.42 ± 0.74 mg of RNA hydrolyzed/min/mg protein, 0.45 ± 0.18 ng RNA hydrolyzed/min/ng protein and 0.28 ± 0.07 ng RNA hydrolyzed/min/ng protein for the tRNAtotal, mRNA transcribed and tRNA^phe, respectively, for C. procera; and 0.02 ± 0.001 ng RNA hydrolyzed/min/ng protein for the mRNA transcribed and tRNA^phe in P. tithymaloides. This is the first report of RNases enzymes in the latex from these species.

Palavras-chave : Laticifer enzyme; crude extract; RNA; tropical plants.

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