Neurochemistry Flashcards
Rate limiting step in dopamine metabolism
Tyrosine hydoxylase
Converts L-tyrosine to L-DOPA
L-phenylalanine–>L-tyrosine–>L-DOPA–>dopamine
In dopamine metabolism, L-phenylalanine is converted to L-tyrosine by which enzyme?
Phenylalanine hydroxylase
L-tyrosine is converted to L-DOPA by which enzyme?
Tyrosine hydroxylase
L-DOPA is converted to dopamine by which enzyme?
DOPA decarboxylase (with pyridoxal phosphate as cofactor)
Dopamine is a precursor in the synthesis of which neurotransmitters?
Noradrenaline and adrenaline
Dopamine is converted to noradrenaline by which enzyme?
Dopamine β-hydroxylase
Noradrenaline is converted to adrenaline by which enzyme?
Phenylethanolamine N-methyl transferase (PNMT)
S-adenosyl-L-methionine (SAM) is the cofactor
Dopamine is broken down to inactive metabolites by monoamine oxidase (MAO-B), aldehyde dehydrogenase (ALDH), and which other enzyme?
Catechol-O-methyl transferase (COMT)
Rate limiting step in manufacture of glycine
Serine trans-hydroxymethylase
Glycine is biosynthesized in the body from which amino acid?
Serine
The enzyme serine hydroxymethyltransferase catalyses this transformation via the cofactor pyridoxal phosphate.
Rate limiting step in manufacture of GABA
Glutamate decarboxylase
GABA is synthesized from glutamate using the enzyme L-glutamic acid decarboxylase (GAD) and pyridoxal phosphate (which is the active form of vitamin B6) as a cofactor. GABA is converted back to glutamate by a metabolic pathway called the GABA shunt.
This enzyme breaks down noradrenaline to adrenaline
Phenylethanolamine N-methyl transferase (PNMT)
What is the rate limiting step in serotonin synthesis?
Tryptophan hydroxylase
Converts L-Tryptophan to 5hydroxy L-Tryptophan (5HTP
L-Tryptophan–>5hydroxy L-Tryptophan–>Serotonin)
Serotonin is broken down to 5-Hydroxyindoleacetic acid (5-HIAA) by which enzyme?
MAO-A
