What is the difference between fibrous and globular proteins?

Fibrous proteins have a long, rod-like shape and are insoluble in water, while globular proteins are spherical and water-soluble.

Fibrous proteins and globular proteins are two main classes of proteins that differ in their structure, solubility, and functions. Fibrous proteins, as the name suggests, have a fibrous structure, meaning they are elongated and rod-like. They are primarily structural proteins, providing support and shape to cells and tissues. Examples of fibrous proteins include collagen, which provides strength and flexibility to connective tissues, and keratin, which forms the structure of hair and nails. These proteins are generally insoluble in water due to the presence of a high proportion of amino acids with non-polar side chains.

On the other hand, globular proteins have a more compact, spherical shape. They are highly soluble in water, which is a result of the presence of many polar and charged amino acids on their surfaces that can form hydrogen bonds with water. Globular proteins play a wide variety of roles in biological processes. They can act as enzymes, speeding up chemical reactions, or as antibodies, fighting against foreign substances in the immune system. Examples of globular proteins include haemoglobin, which carries oxygen in the blood, and insulin, which regulates blood sugar levels.

In terms of structure, fibrous proteins usually have a repetitive sequence of amino acids and a simple, regular structure, such as a helix or a pleated sheet. This is in contrast to globular proteins, which have a more complex, irregular structure with several different regions, each with a different function. This complex structure is the result of the protein folding up on itself, with the hydrophobic (water-hating) parts on the inside and the hydrophilic (water-loving) parts on the outside.

In summary, fibrous proteins and globular proteins differ in their shape, solubility, and function. Fibrous proteins are long and rod-like, insoluble in water, and provide structural support, while globular proteins are spherical, water-soluble, and involved in a wide range of biological processes.