Navegando por Autor "Monteiro, Norberto K.V."
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Artigo CvL, a lectin from the marine sponge Cliona varians: Isolation, characterization and its effects on pathogenic bacteria and Leishmania promastigotes(Elsevier, 2006) Queiroz, Alexandre F.S.; Moura, Raniere M.; Fook, Jacy M.S.L.L.; Dias, Anny S.F.; Monteiro, Norberto K.V.; Ribeiro, Jannisson K.C.; Moura, Gioconda E.D.D.; Macedo, Leonardo L.P.; Santos, Elizeu A.; Sales, Maurício P.CvL, a lectin from the marine sponge Cliona varians was purified by acetone fractionation followed by Sepharose CL 4B affinity chromatography. CvL agglutinated papainized treated human erythrocytes with preference for type A erythrocytes. The lectin was strongly inhibited by monosaccharide D-galactose and disaccharide sucrose. CvL is a tetrameric glycoprotein of 28 kDa subunits linked by disulphide bridges with a molecular mass of 106 kDa by SDS-PAGE and 114 kDa by Sephacryl S300 gel filtration. The lectin was Ca2+ dependent, stable up to 60 °C for 60 min, with optimum pH of 7.5. CvL displays a cytotoxic effect on gram positive bacteria, such as Bacillus subtilis and Staphylococcus aureus. However, CvL did not affect gram negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa. Leishmania chagasi promastigotes were agglutinated by CvL up to 28 titer. These findings are indicative of the physiological defense roles of CvL and its possible use in the antibiosis of bacteria and protozoa pathogenic.Artigo QTAIM and NCI analysis of intermolecular interactions in steroid ligands binding a cytochrome P450 enzyme – Beyond the most obvious interactions(Computational And Theoretical Chemistry, 2017-04-17) Firme, Caio Lima; Monteiro, Norberto K.V.; Silva, Sérgio R.B.The 17a-hydroxylase-17,20-lyase (CYP17) is a cytochrome P450 enzyme which participates in steroid hormones metabolism. Pregnenolone (PREG) is its natural steroid substrate and abiraterone (ABE) is a well-known steroid inhibitor. In this paper, QTAIM and NCI analysis indicate many non-familiar inter- molecular interactions in CYP17-ABE and CYP17-PREG complexes beyond the obvious interactions in these systems. These obvious interactions are two H-bonds in CYP17-PREG and NAFe interaction in CYP17-ABE. Docking, molecular dynamics and ONIOM protocol was used to obtain the low-lying geome- tries for further topological analysis. QTAIM analysis from xB97XD/6-311G++(d,p) wave function indi- cated the existence of H-bonds in CYP17-PREG complex and also showed three moderately strong intermolecular interactions in CYP17-ABE complex (besides the strong pyridine N-HEME Fe interaction): (O)HAH (Ile205) interaction, (C)HAN interaction (Arg239) and HAH bond (Asp298), indicating that these interactions play a secondary role on molecular recognition of ABE by CYP17. QTAIM also indicated that HAH bonds are important in molecular recognition since they made up half of all pairwise interactions, although being weaker than other usual interaction (hetereoatom-H intermolecular interaction), with two exceptions (which are closer than other HAH bonds). Further NCI results give further evidence that ABE pyridine-HEME interaction has multiple interactions besides the obvious NAFe interaction which might decrease the flexibility of the yet rigid ABE backbone in order make H-bonds from its (C3)- hydroxyl group with CYP17 binding pocket