Estudo in silico das interações da protease NS3-NS2B de DENV-2 com o inibidor peptídico Bz-nKRR-H com finalidades terapêuticas

Dengue virus is an important patogen that causes Dengue desease in all world, and belongs to Flavivirus gender. The virus consists of enveloped RNA with a single strand positive sense, 11Kb genome. The RNA is translated into a polyprotein precursor, wich is cleaved into 3 structural proteins (C, prM e E) and 7 non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B e NS5). The NS3 is a multifunctional protein, that besides to promote the polyprotein precursor cleavage, also have NTPase, helicase and RTPase activity. The NS3 needs a hydrophilic segment of 40 residues from the transmembrane NS2B protein (who acts like cofator) to realize this functions. Actually, there's no vacines available on the market, and the treatment are just symptomatic. The tetrapeptide inhibitor Bz-Nle-Lys-Arg-Arg-H (Ki de 5,8-7,0 M) was showed as a potent inhibitor μ for NS3prot in Dengue virus. That is a inteligent alternative to treat the dengue desease. The present work aimed analyse the interactions of the ligand bounded to the activity site to provid a clear and depth vision of that interaction. For this purpouse, it was conducted an in silico study, by using quantum mechanical calculations based on Density Functional Theory (DFT), with Generalized Gradient approximation (GGA) to describe the effects of exchange and correlation. The interaction energy of each amino acid belonging to the binding site to the ligand was calculated the using the method of molecular fragmentation with conjugated caps (MFCC). Besides energy, we calculated the distances, types of molecular interactions and atomic groups involved. The theoretical models used were satisfactory and show a more accurate description when the dielectric constant = 20 ε and 80 was used. The results demonstrate that the interaction energy of the system reached convergence at 13.5 A. Within a radius of 13,5A the most important residues were identified. Met49, Met84 and Asp81 perform interactions of hydrogen with the ligant. The Asp79 and Asp75 residues present high energy of attraction. Arg54, Arg85 and Lys 131 perform hydrogen interactions with the ligand, however, appear in BIRD graph having high repulsion energy with the inhibitor. The data also emphasizes the importance of residue Tyr161 and the involvement of the catalytic triad composed by Asp75, His51 and Ser135

Alterações nos genes da E-caderina e β-catenina em adenoma pleomórfico e carcinoma adenóide cístico: estudo molecular e imuno-histoquímico

Pleomorphic adenoma and adenoid cystic carcinoma represent a benign and malignant salivary gland neoplasm, respectively, that shares the same histological origin, however with distinct biological behavior. The aim of the present study was identify the -160 C/A polymorphism in the gene CDH1, mutational analysis of CTNNB1 gene and evaluation the expression of the E-cadherin and β-catenin in pleomorphic adenomas and adenoid cystic carcinomas. Furthermore, it was proposed correlate the immunochemistry staining patterns with the polymorphism and mutations. Twenty-four pleomorphic adenomas and 24 adenoid cystic carcinomas were retrieved. The polymorphism analysis was performed by restriction fragment length polymorphism (RFLP), using the restriction enzymes HphI or AflIII and the mutational screening was performed by PCR-single strand conformational polymorphism (PCR-SSCP). The immunohistochemical analysis was taken by the counting of cells, recorded as the Hscore index, and considering the presence or absence, intensity, distribution and localization of proteins expression. Comparing the two neoplasms, the results demonstrated statistically significant difference for the E-cadherin and β-catenin expression, with pleomorphic adenoma presenting weaker immunostaining. Was observed statistical correlation between E-cadherin and β-catenin expression. CDH1 heterozigotic polymorphism was seen in two cases and 13 cases displayed abnormal mobility electrophoretic shifts, suggesting CTNNB1 gene mutation. The immunohistochemical expression was not statistically correlated with the polymorphism or suggested mutations. In conclusion this study supports that the E-cadherin/β-catenin complex immunohistochemical expression might be related with the myoepithelial component amount and differentiation neither the tumor biological behavior. The cases that showed E-cadherin gene polymorphism presented reduced protein expression and, moreover, CTNNB1 suggested mutations seem not influence in the β-catenin protein expression