Complex sentence: The hydrophobic character of amino acids is believed by researchers to be the main driving force of protein folding and stability as it causes the non polar side chains to pack together in the protein interior to avoid contact with water.
Split into simpler sentences: The hydrophobic character of amino acids is believed by researchers to be the main driving force in protein folding. Hydrophobicity provides stability to the protein structure, because it causes the non polar side chains to pack together in the interior of the protein to avoid contact with water.