Purification and Partial Characterization of Lectins from leaves and bark of Caesalpinia ferrea
Nascimento-Silva, S., Paes-Barreto, R.S., Ximenes, N.C.A., Coelho, L.C.B.B., Correia, M.T.S.
Departamento de Bioquímica, CCB, UFPE, Av. Prof. Moraes Rego, S/N, Recife - PE, CEP: 50670-910, Brasil. E-mail:snascimento-@hotmail.com
Lectins are proteins that bind specifically and reversibly to carbohydrates. These purified proteins have been used in biological and medical investigations. Caesalpinia ferrea Mart. is a legume (jucá, pau-ferro, iron-wood) broadly distributed at North and Northeast Regions of Brazil. Different C. ferrea tissues have been used in popular medicine, which waked the interest to isolate and purify these plant lectins. C. ferrea pod lectin (CfePL), previously purified, showed a potent antimicrobial activity. The aim of this work was a comparative evaluation of extraction, purification and partial characterization from C. ferrea leaf and bark lectins with CfePL. Extracts of leaves (10 %) in citrate phosphate buffer, pH 6.5 and of bark (10 %) in 0.15M NaCl, were ammonium sulphate fractionated (0-80 %) and chromatographed on chitin column; leaves (CfeLL) and bark (CfeBL) lectins were eluted with 1.0 M acetic acid (pH 4.0). Hemagglutinating activity (HA) of preparations was evaluated with different erythrocytes, ions (Ca2+ and Mg2+), pH values (2 – 12), carbohydrates and glycoproteins, as well as temperatures (30 – 100 °C, 30 min). CfeLL and CfeBL were evaluated by PAGE for basic protein, as well as under denatured and reduced conditions. CfeLL and CfeBL showed a chromatographed profile similar to that obtained for CfePL purification. The lectins did not show specificity to human erythrocytes and differently from CfePL were not stimulated by ions solutions. HA of CfeLL, CfeBL and CfePL were partially inhibited by glycoproteins (fetuin, rabbit and fetal serum); activities were stable at temperature treatments (maintained the activity even after heating to 100 °C for 1 h) and in the presence of pH values. Both lectins were basic proteins and showed an electrophoretic pattern similar to CfePL. In conclusion, C. ferrea leaf and bark lectins were purified by chitin column using a low cost eluent solution and had similar characteristics to CfePL; they will be assayed as potential antimicrobial agents.
Supported by: CNPq, FACEPE and CAPES.
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