Peptide Drug Discovery refers to the use in human medicine of short chains of amino acids, called polypeptides, that have a biological activity that is therapeutic value in man. Among the best known of the naturally-occurring polypeptides of this nature are enkephalins and endorphins. Synthetic analogues of the substances manufactured within the body have been discovered to have therapeutic value as drugs.
Endorphins are morphine-like molecules that are made in the body. They are referred to as endogenous opioid peptides; endogenous because they are produced internally and opioid because they are similar to drugs made by the opium poppy. Drugs that actually come from the opium poppy, such as heroin, codeine and morphine, are referred to as opiates. Both opiates and opioids work on systems in the brain responsible for emotion, appetite control, pain and stress.
Another group of small polypeptides, about five amino acids in length, are the tachykinin polypeptides. These include Kassinin, Neurokinins A and B, Eledoisin and Substance P. They get their name from the facility with which they cause smooth muscle tissue in the gut to rapidly contract. Another group, the vasoactive intestinal peptides, contain around 28 amino acids, making them considerably larger molecules than the tachykinins. Along with vasoactive intestinal peptide itself, the group includes pituitary adenylate cyclase activating peptide (PACAP), growth hormone releasing hormone (GHRF), secretin, glucagon and PHI, or peptide histidine isoleucine.
The calcitonin peptides form a fourth group of this type of molecule. These include calcitonin itself, along with AGG01 and Amylin. Within the human body, calcitonin is manufactured in the thyroid gland by the parafollicular cells. It counters the effects of parathyroid hormone by decreasing the amount of circulating calcium ions. Calcitonin derived from salmon is used as a treatment in postmenopausal women for osteoporosis. It is also used in the general population to treat phantom limb pain, bone metastases, Paget's disease and hypercalcemia (elevated plasma calcium levels).
The pancreatic polypeptide-related peptides include neuropeptide Y (NPY), PYY (peptide YY), APP (avian pancreatic polypeptide) and PPY (pancreatic polypeptide). Pancreatic polypeptide consists of about 36 amino acids and has a molecular weight of 4200 Daltons (a dalton is a unit of molecular mass and is equivalent to 1 g/mol).
Pancreatic polypeptide controls hepatic glycogen levels, modulates secretions in the digestive tract and controls the secretory functions in the pancreas. These secretions may be endocrine, acting on the pancreas itself, or exocrine, acting on distant organs. PP is secreted by the pancreas in response to a protein meal, fasting, exercising or during a bad attack of hypoglycemia. Ingesting glucose can reverse these effects.
Two very small groups of therapeutic polypeptides are the lactotripeptides and basic natriuretic peptide (BNP). The lactotripeptides consist of two polypeptides, each only three amino acid residues in length. They occur naturally in milk and have been credited with a possible activity in reducing blood pressure. BNP, also called B-type natriuretic peptide, is made up of 32 amino acids.
Peptide drug discovery is a promising area of medicine because it is relatively simple to manufacture short amino acids in the laboratory. Calcitonin that is used medically is derived from salmon. Because the molecules are so short, they are not long enough to generate an immune response and so it is possible to use animal-derived versions. So far, we have been able to synthesize drugs that operate on the thyroid, pancreas and central nervous system. The lactotripeptides may one day help to control hypertension.
Endorphins are morphine-like molecules that are made in the body. They are referred to as endogenous opioid peptides; endogenous because they are produced internally and opioid because they are similar to drugs made by the opium poppy. Drugs that actually come from the opium poppy, such as heroin, codeine and morphine, are referred to as opiates. Both opiates and opioids work on systems in the brain responsible for emotion, appetite control, pain and stress.
Another group of small polypeptides, about five amino acids in length, are the tachykinin polypeptides. These include Kassinin, Neurokinins A and B, Eledoisin and Substance P. They get their name from the facility with which they cause smooth muscle tissue in the gut to rapidly contract. Another group, the vasoactive intestinal peptides, contain around 28 amino acids, making them considerably larger molecules than the tachykinins. Along with vasoactive intestinal peptide itself, the group includes pituitary adenylate cyclase activating peptide (PACAP), growth hormone releasing hormone (GHRF), secretin, glucagon and PHI, or peptide histidine isoleucine.
The calcitonin peptides form a fourth group of this type of molecule. These include calcitonin itself, along with AGG01 and Amylin. Within the human body, calcitonin is manufactured in the thyroid gland by the parafollicular cells. It counters the effects of parathyroid hormone by decreasing the amount of circulating calcium ions. Calcitonin derived from salmon is used as a treatment in postmenopausal women for osteoporosis. It is also used in the general population to treat phantom limb pain, bone metastases, Paget's disease and hypercalcemia (elevated plasma calcium levels).
The pancreatic polypeptide-related peptides include neuropeptide Y (NPY), PYY (peptide YY), APP (avian pancreatic polypeptide) and PPY (pancreatic polypeptide). Pancreatic polypeptide consists of about 36 amino acids and has a molecular weight of 4200 Daltons (a dalton is a unit of molecular mass and is equivalent to 1 g/mol).
Pancreatic polypeptide controls hepatic glycogen levels, modulates secretions in the digestive tract and controls the secretory functions in the pancreas. These secretions may be endocrine, acting on the pancreas itself, or exocrine, acting on distant organs. PP is secreted by the pancreas in response to a protein meal, fasting, exercising or during a bad attack of hypoglycemia. Ingesting glucose can reverse these effects.
Two very small groups of therapeutic polypeptides are the lactotripeptides and basic natriuretic peptide (BNP). The lactotripeptides consist of two polypeptides, each only three amino acid residues in length. They occur naturally in milk and have been credited with a possible activity in reducing blood pressure. BNP, also called B-type natriuretic peptide, is made up of 32 amino acids.
Peptide drug discovery is a promising area of medicine because it is relatively simple to manufacture short amino acids in the laboratory. Calcitonin that is used medically is derived from salmon. Because the molecules are so short, they are not long enough to generate an immune response and so it is possible to use animal-derived versions. So far, we have been able to synthesize drugs that operate on the thyroid, pancreas and central nervous system. The lactotripeptides may one day help to control hypertension.
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