Complex sentence: The amino acids and sugars presumably help to decrease the ice content colligatively; however, they probably also have a direct protective effect on membranes and proteins via direct interaction or by modifying the water layer with the closest proximity to the molecules.
Split into simpler sentences: The amino acids and sugars presumably help to decrease the ice content colligatively. However, they probably also have a direct protective effect on membranes and proteins via direct interaction or by modifying the water layer with the closest proximity to the molecules.