The document discusses interactions between amino acids, specifically glutamic acid and lysine, which can form hydrogen bonds and van der Waals forces due to their differing polarities. Additionally, it examines phenylalanine and isoleucine, noting phenylalanine's hydrophobic nature and aromaticity which allows for unique noncovalent interactions that isoleucine cannot partake in. Overall, the focus is on the types of interactions based on the chemical properties of these amino acids.

1. Glutamic acid and Lycine: Hydrogen bonding could occur between the NH3+
group of Lysine and the COO- group of Glutamic acid; and Van der Waals (nonpolar-nonpolar)
forces/interactions could arise between the nonpolar methylene groups of both R groups.
Phenylalanine and Isoleucine: Phenylalanine is quite hydrophobic so it works in hydrophobic
reactions. Both have nonpolar R groups so the only interactions they could undergo would be the
weakly attractive Van der Waals forces between the methylene groups of both R groups.
However, Phenylalanine is an aromatic compound with an aromatic ring, which is capable of
undergoing noncovalent Pi-system interactions but not with Isoleucine because it is not polar
enough to distort the Pi system of the aromatic ring.
Solution
Glutamic acid and Lycine: Hydrogen bonding could occur between the NH3+
group of Lysine and the COO- group of Glutamic acid; and Van der Waals (nonpolar-nonpolar)
forces/interactions could arise between the nonpolar methylene groups of both R groups.
Phenylalanine and Isoleucine: Phenylalanine is quite hydrophobic so it works in hydrophobic
reactions. Both have nonpolar R groups so the only interactions they could undergo would be the
weakly attractive Van der Waals forces between the methylene groups of both R groups.
However, Phenylalanine is an aromatic compound with an aromatic ring, which is capable of
undergoing noncovalent Pi-system interactions but not with Isoleucine because it is not polar
enough to distort the Pi system of the aromatic ring.