Norepinephrine, adrenaline from biosynthesis

In addition to their well known role in protein structure, amino acids also act as precursors to a number of other important biological molecules. For example, the synthesis of haem (see also Section 5.3.1), which occurs in, among other tissues, the liver begins with glycine and succinyl-CoA. The amino acid tyrosine which maybe produced in the liver from metabolism of phenylalanine is the precursor of thyroid hormones, melanin, adrenaline (epinephrine), noradrenaline (norepinephrine) and dopamine. The biosynthesis of some of these signalling molecules is described in Section 4.4. 

Thyroliberin, thyrotropin-releasing hormone, TRH, pGlu-His-Pro-NH2, produced in the paraventricular nucleus of the hypothalamus, stimulates biosynthesis and secretion of thyrotropin (TSH) from the anterior pituitary. It is central in regulating the hypothalamic-pituitary-thyroid (HPT) axis. Furthermore, TRH influences the release of other hormones, e.g., prolactin, growth hormone, vasopressin, insulin, and also the classic neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline). In addition, it is... 

Dopamine (4) serves as key intermediate in the biosynthesis of the stress hormone adrenaline (7). Two different routes are available for the biosynthesis of 4 from tyrosine (1). Hydroxylation of the aromatic ring, catalyzed by tyrosine hydroxylase, affords l-DOPA (2), which is converted to dopamine (4) via a decarboxylation step. Alternatively, tyrosine decarboxylase-mediated decarboxylation of tyrosine delivers tyramine that can be hydroxylated to afford the important bioactive intermediate 4. Hydroxylation of the benzylic position in 4 then leads to the formation of norepinephrine, also known as noradrenaline (6), which upon methylation of the amine is converted to epinephrine (adrenaline, 7) [1]. 

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