RESUMO
Latex, a milky fluid found in several plants, is widely used for many purposes, and its proteins have been investigated by researchers. Many studies have shown that latex produced by some plant species is a natural source of biologically active compounds, and many of the hydrolytic enzymes are related to health benefits. Research on the characterization and industrial and pharmaceutical utility of latex has progressed in recent years. Latex proteins are associated with plants' defense mechanisms, against attacks by fungi. In this respect, there are several biotechnological applications of antifungal proteins. Some findings reveal that antifungal proteins inhibit fungi by interrupting the synthesis of fungal cell walls or rupturing the membrane. Moreover, both phytopathogenic and clinical fungal strains are susceptible to latex proteins. The present review describes some important features of proteins isolated from plant latex which presented in vitro antifungal activities: protein classification, function, molecular weight, isoelectric point, as well as the fungal species that are inhibited by them. We also discuss their mechanisms of action.
Assuntos
Antifúngicos/farmacologia , Quitinases/farmacologia , Látex/química , Peptídeo Hidrolases/farmacologia , Peroxidases/farmacologia , Lectinas de Plantas/farmacologia , Proteínas de Plantas/farmacologia , Antifúngicos/classificação , Antifúngicos/isolamento & purificação , Botrytis/efeitos dos fármacos , Botrytis/crescimento & desenvolvimento , Candida albicans/efeitos dos fármacos , Candida albicans/crescimento & desenvolvimento , Quitinases/classificação , Quitinases/isolamento & purificação , Quitinases/fisiologia , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Ponto Isoelétrico , Testes de Sensibilidade Microbiana , Peso Molecular , Peptídeo Hidrolases/classificação , Peptídeo Hidrolases/isolamento & purificação , Peptídeo Hidrolases/fisiologia , Peroxidases/classificação , Peroxidases/isolamento & purificação , Peroxidases/fisiologia , Doenças das Plantas/microbiologia , Extratos Vegetais/química , Lectinas de Plantas/classificação , Lectinas de Plantas/isolamento & purificação , Lectinas de Plantas/fisiologia , Proteínas de Plantas/classificação , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/fisiologia , Plantas/químicaRESUMO
EPL-1 and EPL-2 represent lectins isolated from the green alga Enteromorpha prolifera. Both lectins are 20- to 22-kDa single-chain, nonglycosylated proteins. N-terminal sequence analysis of peptides representing over 70% of their primary structures shows that EPL-1 and EPL-2 represent novel proteins. Sedimentation-diffusion equilibrium experiments showed that EPL-1 and EPL-2 had average apparent molecular masses of 60000+/-6000 Da (EPL-1) and 59500+/-3000 Da (EPL-2), indicating that EPL-1 and EPL-2 have a tendency to self-associate into higher order aggregates, possibly homodimers and homotetramers, in equilibrium. The carbohydrate-binding specificity of EPL-2 was studied by enzyme-linked lectin assay and intrinsic fluorescence measurements. The results show that the combining site of EPL-2 is capable of accommodating both D-mannose and L-fucose, which share the conformation of the hydroxyl groups at positions 2 (axial) and 4 (equatorial), and includes subsites for the substituents at O1 and for branched mannose residues.