Aggregation characteristics of non-aromatic polar amino acids and its association to amyloids

Aggregation of amino acids to amyloid like structures is known to have implications in the pathophysiology of single amino acids based inborn-errors of metabolism (IEMs). Studying the aggregation properties of amino acids is of crucial interest also to understand the association of these IEMs to amyloid associated diseases. Hence, herein we have studied the self-assembly of different non-aromatic charged/uncharged polar amino acids namely L-Glutamine (Gln), L-Aspartic acid (Asp), L-Glutamic acid (Glu) L-Histidine (His), L-Arginine (Arg), L-Serine (Ser) and L-Threonine (Thr) whose amyloid characteristics have still not been explored by ageing them for varying time intervals from 0-15 days in aqueous solution. The structure formation by the self-assembly of these amino acids were then studies by microscopy., Notably, of all amino acids glutamine revealed amyloid like febrile morphologies as observed in case of aromatic amino acids. The MTT assay also revealed a relatively more cytotoxic nature of glutamine assemblies as compared to other amino acid aggregates and suggests it may have amyloid like characteristics. Along with Gln, Asp and Glu also revealed formation of some unique self-assembled structures. The thioflavin T assay suggests these aggregates may have amyloid nature. Hence, the aggregation studies of these amino acids may have important implication in the pathogenesis of disease caused by the accumulation of glutamine, aspargine and aspartic acid.