Abstract

Alpha 1- antitrypsin (alpha 1AT) a 54 kDa glycoprotein is a protease inhibitor. In the absence of alpha 1AT, elastase released by lung macrophages, was not inhibited and lead to elastin breakdown and pulmonary problems such as emphysema or COPD. alpha 1AT has three site of N-glycosylation and a characteristic reactive central loop (RCL). As small-scale medicines are preferred for pulmonary drug delivery, in this study alpha 1ATs (1, 2, 3, 4 and 5) were engineered and shortened from the N-terminal region. In order to investigate the effect of different mutations and the deletion of 46 amino acids theoretical studies were performed. Homology modeling was performed to generate the 3D structure of alpha 1ATs. The 10 ns Molecular Dynamic (MD) simulations were carried out to refine the models. Results from MD and protein docking showed that alpha 1AT2 has the highest binding affinity for neutrophil elastase, provided the basis for the experimental phase in which sequences from the five alpha 1AT constructs were inserted into the expression vector pGAPZ alpha and expressed in the yeast Pichia pastoris. Although, the alpha 1AT2 construct has the highest inhibitory activity even more that the native construct (alpha 1AT5), results indicated the presence of protease inhibitory function of all the proteins' construct against elastase.