Download Amino Acid-Derived Hormones

Amino Acid-Derived Hormones
Of the amino acid-derived hormones, some circulate for only a few
minutes while others may circulate for days. The amino acid tyrosine is
the precursor for two groups of hormones: the thyroid hormones,
produced in the thyroid gland; and the catecholamines (epinephrine and
norepinephrine), produced in the adrenal medullae. The amino acid
tryptophan is the precursor for the hormone melatonin, secreted by the
pineal gland, and the hormone serotonin, which is quite widespread in
the body. Some of these hormones have a circulating half-life of a few
days (thyroid hormones) while some are rapidly degraded
(catecholamines).