Proteins

Proteins: the workhorse biomolecule

Proteins are the single most abundant class of biomolecule in any living system. They are found in every tissue and every part of the body, and they underpin both the structure and the function of life — muscle, skin, hair and connective tissue are built from them, enzymes that drive metabolic reactions are proteins, hormones that regulate the body are proteins, antibodies that fight infection are proteins, and haemoglobin that transports oxygen is a protein. The body's growth and day-to-day maintenance depend on an adequate protein supply, which is why milk, cheese, pulses, peanuts, fish and meat — all rich protein sources — form a staple part of the diet.

The name itself is telling: "protein" comes from the Greek proteios, meaning "primary" or "of first importance" — a fitting name for a molecule this central to biology. …