EXPLORING PROTEIN STRUCTURE Discuss the properties of the following fibrous proteins in relation to their structure and function: Collagen Fibroin Keratin Some globular proteins, such as actin, can link together to form filaments. Discuss the importance of this property for cells. Discuss how the microtubules of the cell cytoskeleton form. Relate this structure to the function of the cell cytoskeleton. Enzymes are globular proteins that catalyse reactions in a highly specific manner. Discuss how catalase increases the rate of reaction for removing hydrogen peroxide from cells so it does not reach toxic levels.