<P> As the helices are interconnected, all helices in a crystal must have the same molecular handedness . This is determined when the crystal is nucleated and can thus be forced by seeding . The resulting crystals have been used to separate racemic mixtures . </P> <P> Urea dissolved in water is in equilibrium with the isomeric ammonium cyanate . The resulting activity of the isocyanic acid ions do result in carbamylation (formation of long - chain carbamides, liberating ammonia molecule as byproduct) of proteins if proteins are present in the solution too . The carbamylation reaction may occurs at elevated temperatures even without catalysts . At room temperature, water solutions of urea are prone to same decomposition reaction in the presence of urease . The isomerization of urea in solution at room temperature without catalysts is a slow process (taking days to reach equilibrium), and freshly prepared, unheated solutions had negligible carbamylation rates . </P> <P> Urea reacts with alcohols to form urethanes . </P> <P> Urea reacts with malonic esters to make barbituric acids . </P>

Where is urea produced in the human body