Isolamento, caracterização e avaliação da atividade antimicrobiana de uma nova lectina do peixe Talassophryne nattereri

Abstract

Lectins are proteins that have the ability to bind reversibly to carbohydrates and exhibit a wide variety of biological activities. Furthermore, these proteins are present in almost all living organisms, several lectins were isolated and subsequently characterized in various fish. The Thalassophryne nattereri is a venomous fish that inhabits the North and Northeast Brazil and is a rich source of lectin, which can be found in its venom. Among the biological activities that have lectins is antimicrobial activity, which is the ability to inhibit the growth of microorganisms. Thus, this research aimed to purify and characterize a new lectin found in T. naterreri fish and evaluated the antimicrobial activity of lectin on microorganisms of medical importance. The lectin called TnSL was isolated by filtration gel chromatography (FPLC, Sephacryl S-100, 50mM Tris-HCl 0,5M NaCl pH8,0) from the crude extract of the fish mucus, obtained by scraping the fish skin. The presence of protein in the sample was verified by hemagglutination activity (HA). TnSL was characterized by polyacrylamide gel electrophoresis containing sodium dodecyl sulfate (SDS-PAGE 12%), as well as carbohydrate inhibition test, thermal stability and evaluation of stability at various pH and ion values. The antimicrobial activity of the lectin on the growth of the microorganisms was evaluated by determining the minimum inhibitory concentration (MIC) in bacteria and fungi. Filtration gel chromatography showed a single protein peak with hemagglutinating activity and 12% SDS-PAGE revealed a single band of approximately 20kDa. TnSL presented thermal stability and at different values of pH. It was a Ca-independent lectin with bacteriostatic activity, but did not showed antifungal activity against the yeasts tested. In this context, a single chromatographic step resulted in a new lectin present in this fish species, which was isolated for the first time through this work, whose antimicrobial and biotechnological potential is under study.