Amino acids that match the description: the r-groups of this classof amino acids are nonpolar and hydrophobic, and their side chains tend tocluster together within proteins, stabilizing protein structure by means ofhydrophobic interactions.1. lysine2. leucine3. isoleucine4. alanine

Leucine, isoleucine and alanine.

Explanation:

Leucine, isoleucine and alanine belong to a group of amino acids called nonpolar amino acids. They have R groups which are aliphatic in nature, which makes them hydrophobic (afraid of water). Proteins that contain these amino acids when present in aqueous solution, tend to fold into a three dimensional structure, burying the hydrophobic side chains in the inner part of the protein structure.

Lysine belongs to a group of amino acids called basic amino acids. Their side chains can accept a proton, thus basic.