Navegando por Palavras-chave "proteinase"
Agora exibindo 1 - 2 de 2
Resultados por página
Opções de Ordenação
- ItemSomente MetadadadosCathepsin B carboxydipeptidase specificity analysis using internally quenched fluorescent peptides(Portland Press, 2002-11-15) Cezari, Maria Helena S [UNIFESP]; Puzer, Luciano [UNIFESP]; Juliano, Maria Aparecida [UNIFESP]; Carmona, Adriana Karaoglanovic [UNIFESP]; Juliano, Luiz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)We have examined in detail the specificity of the subsites S-1, S-2, S-1' and S-2' for the carboxydipeptidase activity of cathepsin B by synthesizing and assaying four series of internally quenched fluorescent peptides based on the sequence Dnp-GFRFW-OH, where Drip (2,4-dinitrophenyl) is the quenching group of the fluorescence of the tryptophan residue. Each position, except the glycine, was substituted with 15 different naturally occurring amino acids. Based on the results we obtained, we also synthesized efficient and sensitive substrates that contained o-aminobenzoic acid and 3-Dnp-(2,3-diaminopropionic acid), or epsilon-amino-Dnp-Lys, as the fluorescence donor-receptor pair. the higher kinetic parameter values for the carboxydipeptidase compared with the endopeptidase activity of cathepsin B allowed an accurate analysis of its specificity. the subsite S-1 accepted preferentially basic amino acids for hydrolysis; however, substrates with phenylalanine and aliphatic side-chain-containing amino acids at P-1 had lower K-m values. Despite the presence of Glu(245) at S-2, this subsite presented clear preference for aromatic amino acid residues, and the substrate with a lysine residue at P-2 was hydrolysed better than that containing an arginine residue. S-1' is essentially a hydrophobic subsite, and S-2' has particular preference for phenylalanine or tryptophan residues.
- ItemSomente MetadadadosPoliovirus 3C proteinase inhibition by organotelluranes(Walter de Gruyter & Co, 2011-04-01) Gouvea, Iuri E. [UNIFESP]; Santos, Jorge A. N. [UNIFESP]; Burlandy, Fernanda M.; Tersariol, Ivarne L. S.; Silva, Edson E. da; Juliano, Maria A. [UNIFESP]; Juliano, Luiz [UNIFESP]; Cunha, Rodrigo L. O. R. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Inst Oswaldo Cruz; Univ Mogi das Cruzes; Universidade Federal do ABC (UFABC)The 3C proteinase, essential for human poliovirus (PV) replication, has unique characteristics as its three-dimensional structure resembles chymotrypsin, but its catalytic nucleophile is a cysteine SH group rather than the OH group of serine. Here, we describe the use of tellurium compounds as inhibitors of PV3C proteinase. A rapid, stoichiometric and covalent inactivation of PV3C was observed with both a chloro-telluroxetane and a bis-vinylic organotellurane. These compounds also inhibit human cathepsins B, L, S, and K with second order rate constants higher than those obtained for PV3C. Chloro-telluroxetane inhibits replication of PV in human embryonic rhabdomyosarcoma cells in the low micromolar range and below the toxic level for the host cells. Bis-vinylic organotellurane is more effective as antiviral agent but reduces the cell viability by 20% at 10 mM, a concentration almost completely inhibiting virus growth. This is the first description of inhibition of viral 3C proteinase with antiviral property by this class of compounds.