Does Arginine Aggregate Formation in Aqueous Solutions Follow Two-Step Mechanism?

The formation of aggregates was studied in amino acid aqueous solutions. Regarding to arginine (Arg), the main driving force to form aggregates is hydrogen-bonds between the Arg molecules. The measurement of energy loss during this process, coupled with morphology data indicate that this aggregate is in solid state. The aggregation has two steps, with a liquid intermediate stage. An investigation of the effect of pH and solute concentration upon aggregate formation for other amino acid aqueous solutions verifies that aggregate formation is amino-acid specific, while small size of clusters formed by weak interactions lead to large size aggregation. Homochirality is observed in the aggregates; its existence sheds light on the origin of protein homochirality.