Estudos conformacionais por RMN e cálculos teóricos das cadeias peptídicas da distinctina, peptídeo antimicrobiano isolado de Phyllomedusa distincta

Abstract

This work concerns the solid phase synthesis of Chain 1 and Chain 2 of distinctin, an heterodimeric antimicrobial peptide, isolated from the glands of Phyllomedusa distincta anurans. The synthesis herebyused took place, by the means of Fmoc (9-fluorenylmethoxicarbonyl) strategy. In order to obtain information regarding preferencial conformations of these peptides in mediums that mimetize bacterial membranes, some experimental techniques, such as Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) were used, as well as some theoretical methodologies like secondary structure prediction through protein data bases, molecular mechanics and semi-empirical minimizations, besides a wide array of computational techniques for conversion of NMR data into three-dimensional structural models.The CD analysis indicated, for both chains, a high content of -helical forms in aqueous solutions containing various TFE concentrations.The 2D NMR studies, by the usage of techniques such as TOCSY, NOESY, 1H 13C HSQC and 1H 15N HSQC in a 50% TFE aqueous solution, constituted in a part in which all the chemical shift signals wereassigned in these contour maps, based on the results yielded by CD analysis, and also in a part in which the data obtained from the previous step were used to calculate bundles of possible structure models for both chains. This study yielded highly detailed structures for both monomers.