Enzyme Conversion

Full Answer Section

1. Hydroxylation: The enzyme Tyrosine hydroxylase converts Tyrosine to L-DOPA (L-3,4-dihydroxyphenylalanine) in the presence of a cofactor and oxygen.
2. Decarboxylation: The enzyme DOPA decarboxylase removes a carboxyl group from L-DOPA, forming Dopamine.

1. Hydroxylation: Same as Dopamine step 1, Tyrosine hydroxylase converts Tyrosine to L-DOPA.
2. N-methylation: The enzyme Phenylethanolamine N-methyltransferase (PNMT) adds a methyl group to L-DOPA, forming Dopamine.
3. Oxidation: The enzyme Dopamine beta-hydroxylase converts Dopamine to Norepinephrine in the presence of oxygen and a cofactor.

• Both Dopamine and Norepinephrine utilize Tyrosine as a precursor, but their pathways diverge after the initial hydroxylation step.
• Serotonin synthesis doesn't involve methylation, unlike Dopamine and Norepinephrine.

Sample Answer

Neurotransmitter Pathways:

Here's a breakdown of the chemical steps required to create each neurotransmitter, starting with their respective precursor substances:

Serotonin (Precursor: Tryptophan):

1. Hydroxylation: The enzyme Tryptophan hydroxylase converts Tryptophan to 5-Hydroxytryptophan (5-HTP) in the presence of a cofactor and oxygen.

2. Decarboxylation: The enzyme Aromatic L-amino acid decarboxylase removes a carboxyl group from 5-HTP, forming Serotonin.