... sheets. On the other hand, globular proteins have a tertiary structure that is important as is it bent and folded into a 3D spherical shape. Another difference is that fibrous proteins are insoluble in water, whereas globular proteins are soluble in water. Examples of fibrous include keratin and collagen and examples of globular proteins include enzymes (amylase, globulins and insulin), antibodies and hormones. There are also other types of proteins such as simple proteins (albumen, globulins, histones and scleroproteins) and conjugated proteins that have a non-protein group imbedded inside them (glycoproteins, nucleoproteins, chromoproteins and flavoproteins). The first function of proteins is that they can be used for movement animal bodies. Myosin and Actin are filamentous protein molecules contained in muscles. Movement is achieved in the presence of calcium ions because myosin and actin will slide past each other and form a "cross-bridge" structure which contracts the muscle. Muscles are vital ...

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