Exam 2 AA metabolism Flashcards
- What are ketogenic and glucogenic amino acids?
Ketogenic AA are metabolized to Acetyl CoA or acetoacetate.
Glucogenic AA are metabolized to pyruvate, 3-phosphoglycerate α-ketoglutarate, oxaloacetate, fumarate or Succinyl CoA
- What are essential and non-essential amino acids?
Essential AA cannot be synthesized by the body (Pvt Tim Hall acronym)
Name the mandatory keto acid and an amino acid in the transanimation reaction.
α-ketoglutarate is the mandatory keto acid.
Glutamate is the mandatory amino acid.
Describe the role of pyridoxal phosphate (vitamin B6) in the transanimation reaction.
Pyridoxal phosphate is the coenzyme involved in the transanimation reaction. In this reaction, the amino group is transferred from the amino acid to the coenzyme, which transports it to the α-keto acid, forming a new amino acid and regenerating the original coenzyme aldehyde.
- Describe the role of glutamine with reference to nitrogen catabolism.
Glutamine is the transporter of excess nitrogen from the tissues to the liver for the Urea cycle.
What are the substrates and products of glutaminase?
Glutaminase → Glutamate + Ammonia
(glutaminase)
- Name the two cellular compartments where the urea cycle operates.
Mitochondrial matrix and cytosol
. Name a drug that is used for treatment of a urea cycle enzyme deficiency.
carbamoylglutamate
In an exercising muscle, name the cycle that utilizes an amino acid and converts it into glucose.
Glucose-Alanine cycle
Name 2 neurotransmitters that are derived from tyrosine
dopamine
epinephrine
Name 3 types of reactions that are involved in producing a neurotransmitter from an amino acid precursor.
Decarboxylation
Hydroxylation
SAM-dependant methylation
Name 3 catacholamines
dopa, NE , Epi
Name the rate-limiting step in the biosynthesis of catacholamines.
Tyrosine + O2 + THB → DOPA + DHB
(Tyrosine hydroxylase)
Name the cofactor that is required for tyrosine hydroxylase.
Tetrahydrobiopterin
Catecholamine release is stimulated by the neurotransmitter ________?
Acetylcholine
Name two enzymes that are involved in catecholamine catabolism
Catecholamine O-methyltransferase (COMT) Monoamine oxidase (MAO)
Name few functions of catecholamines.
TO prepare the body for the “fight or flight” response:
Increase cardiac output, glycogen degradation, triglyceride hydrolysis and release of fatty acids from adipose tissue.
Decrease peripheral resistance to blood flow.
Discuss the connection between Parkinson’s disease and dopamine and the drug that is used for patients.
Parkinson’s disease is due to a lack of dopamine synthesis. It can be treated by L-DOPA, a precursor of dopamine that can cross the blood-brain barrier.
- Name 2 neurotransmitter compounds derived from tryptophan
Serotonin and melatonin
What are the substrates and products of carbamoyl phosphate synthase.
NH4+ + HCO3- + 2 ATP →
Carbamoyl phosphate + 2 ADP+Pi
(Carbamoyl phosphate synthase I / CPS-I)
Name the allosteric affector of carbamoyl phosphate synthase I
N-acetyl glutamate
What is the hormone that is involved in circadian rhythms?
melatonin
effect of prozac
inhibits reuptake of serotonin
If you suffer from jet lag, what pathway would you target for drug therapy?
melatonin
Name the enzyme that catalyzes the formation of histamine.
histidine carboxylase
Name 3 functions of histamines
Mediate allergic and inflamatory reactions
Vasodiolation
Constriction of bronchioles
Stimulates excretion of HCl
What are the substrates and products of glutamate decarboxylase?
Glutamate → GABA
glutamate decarboxylase
. In general, decarboxylases require the coenzyme ________?
Pyridoxal Phosphate
L-DOPA is used for _______ disease treatment?
Parkinson’s
Name a synthetic compound that limits serotonin reuptake
prozac
Describe pheochromocytoma.
Tumors of chromaffin tissue that produce large amounts of catecholines.
Describe the clinical correlation between Huntington’s disease and GABA metabolism.
Low levels of GABA and GABAnergic neurons result in the uncontrolled movements of Huntington’s disease
Melanins are synthesized in _______?
Melanocytes
Tyrosinase deficiency causes _____?
albinism
Under oxidative conditions, in order to maintain reducing environment inside the cell, which compound is invoked?
glutathione
Name the methyl group donor compound that is used in the majority of methyl transfer reactions
S-adenosylmethionene (SAM)
Name 2 functions of glutathione.
Maintains protein sulfhydral groups in reduced form. Detoxifies xenobiotics (peroxides and free radicals)
Nitric oxide is derived from the amino acid _____?
Arginine
Name the substrate and products of acetylcholinesterase
Acetylcholine + H2O → Acetate + Choline
(Acetylcholine esterase)
40 Explain the action of DIPF on acetylcholinesterase:
DIPF is a component of nerve gas. It covalently modifies acetylcholinesterase and knocks the enzyme activity.
Name some xenobiotics that inhibit acetylcholinesterase.
hysostigmine
Neostigmine
Name the channel that is opened up by acetylcholine.
Na+ / K+ ion channels
Name three excitatory and three inhibitory neurotransmitters:
Excitatory: acetylcholine aspartate dopamine histamine norepinephrine epinephrine glutamate 5-hydroxy tryptamine
Inhibitory:
glycine
taurine
4-aminobutyrate
Name three stages of nerve transmission:
Resting
Excitation
Termination
What is the function of phenobarbital?
Inhibits action potentials when bound to GABA receptors.
Name the catabolic products of GABA.
Succinate semialdehyde
Succinate
What is an ion-gated channel?
A channel that allows ions to pass through when a neurotransmitter binds to its receptor.Name two ion channels.
name two ion channels
Cholingeric nicotinic receptors
GABA receptors
(More generally, Na+ and K+ ion channels)
Diisopropylphosphoflouridate (DIPF) inhibits the enzyme___________.
acetylcholinesterase
Name two inhibitors of the acetylcholine receptor.
Tubocurarine
α-bungarotoxin
Cobra toxin
What is the action GABA?
GABA is an inhibitory neurotransmitter. Upon binding to its β subunits, it increases membrane permeability of postsynaptic membranes to chloride ion. This can lead to hyperpolarization and increased threshold of triggering an action potential.
