Peptide hormones are a class of hormones composed of amino acids linked together by peptide bonds, making them a type of protein. They function as chemical messengers, transmitting signals from one group of cells to another to regulate physiological and behavioral activities.
Peptide hormones are distinct from steroid hormones, which are derived from cholesterol. While both act as messengers, they perform different functions within the body due to their different chemical structures and mechanisms of action. Peptide hormones are generally water-soluble and bind to receptors on the surface of target cells.
A prominent example of a peptide hormone is insulin. Insulin is crucial for regulating blood glucose levels by signaling cells to take up glucose from the bloodstream. It consists of two peptide chains linked by disulfide bridges.
The behavior of these hormones can be influenced by the pH of their environment, similar to the properties of their constituent amino acids.