4850270
| Question | Answer |
| Rate limiting step? | Tyrosine hyroxylase converting Tyrosine to DOPA (Dihydroxyphenylalanine) |
| Which substance inhibits Tyrosine Hydroxylase? | a-methyl-para-tyrosine |
| Meaning of Rate-limiting step | A critical step in a synthesis/metabolic pathway which determines the rate at which the following reactions go i.e. if its slow they are going to be slow also and vice versa |
| Enzyme which converts DOPA to Dopamine | DOPA Decarboxylase (Aromatic amino acid decarboxylase) |
| DOPA Decarboxylase can be inhibited by? | MK-486 |
| Define a Catechol Ring | Two hydroxyl groups on a benzene ring |
| Dopamine converted to Noradrenaline by? | Dopamine-B-hydroxylase |
| All the enzymes require some sort of ____ for activity or for their reaction to proceed | Cofactor including metal ions |
| Phenylethanolamine-N-methyltrasferase does what? It uses what compound for this? | Converts Noradrenaline to Adrenaline using S-adenosylmethionine |
| From action of Phenylethanolamine-N-methyltransferase, its ____is converted to ______. | Cofactor, S-adenosyl-homocysteine |
| Name the enzymes involved in each step (including the ones not in image) | |
| MAO stands for what? | Monoamine Oxidase |
| MAO pathway of metabolism involves... | Converting Dopamine to an Aldehyde form, aldehyde dehydrogenase then converts this to DOPAC. Finally, COMT converts DOPAC to HVA |
| What does DOPAC stand for? | Dihydroxyphenyl acetic acid |
| What does HVA stand for? | Homovanillic acid |
| Final Product of MAO Dopamine Metabolism Pathway | HVA |
| COMT stands for..... | Catechol-O-methyltransferase |
| COMT Metabolism pathway of Dopamine involves.... | Converting Dopamine to O-methyl dopamine. Then this is converted to aldehyde form by MAO. This form is changed to HVA by action of Aldehyde dehydrogenase |
| Reserpine MOA | Blocks Vesicular Monoamine Transporter = dopamine and other monamines cannot be transported into vesicles for resynaptic release via exocytosis = less dopamine action |
| Amphetamine MOA | Enhances/Stimulates release of Dopamine from presynaptic vesicles |
| Iproniazid MOA | MAO inhibitor = prevent Dopamine metabolism = more dopamine available |
| Imipramine | Prevents re-uptake of Dopamine from synaptic cleft |
| What is an autoreceptor? | It is found on membranes of presynaptic nerve cells. It functions in a negative feedback loop i.e. stops further NT release. It is only sensitive neurotransmitters in which the nerve cell releases |
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