Why Dipeptides Cannot or Will Not Answer Biuret Test for Proteins

Here is an explanation of the Biuret test for Proteins The Biuret reagent works because the Cu2+ cupric ions form a chelating complex with peptides. And it's shaped such that 4 peptide bond Nitrogens donates their electron pair to Copper. This is possible when there are two polypeptides acting from opposite sides. With dipeptides, the orientation can never be right because there'd be just one electron pair per molecule, thus 4 molecules would be required, and these bulky molecules can't huddle together around the Cu