Week 4 Day 1: Urea, AAs, and Heme Flashcards
Name the two main enzymes likely to be deficient in the urea cycle leading to hyperammonemia. And what is so special about the most common deficiency?
Carbomyl phosphate synthetase I (CPSI)
Ornithine trans-carbomylase (OTC)
The most common deficiency is OTC and it’s X-linked recessive.
Where does histamine originate from and what coenzyme does it require?
What’s histamine’s function?
Histamine originates from HISTIDINE and requires pyridoxal phosphate (PLP).
Histamine is:
1. released during allergic reactions
2. binds to H2 receptor to promote HCl secretions in GI
Where does GABA originate from and what coenzyme does it require?
What’s GABA’s function?
GABA originates from GLUTAMATE and requires pyridoxal phosphate (PLP).
GABA is an inhibitory neurotransmitter
Where does serotonin originate from and what coenzyme does it require?
What’s serotinin’s function?
Serotinin originates from TRYPTOPHAN and requires pyridoxal phosphate (PLP).
Serotonin is a neurtransmitter and alters mood. The enzyme monoamine oxidase (MAO) is used to make 5-HIAA.
Where does nitric oxide (NO) originate from?
What’s NO’s function?
NO originates from ARGININE.
NO decreases plasma concentrations of Ca2+ to promote a decrease in the forcefulness of cardiac contraction and promotes vascular relaxation.
Where do the thyroid hormones originate from? What’s their function?
T3 and T4 originate from tyrosine. They increase metabolic rate and increase growth and maturation, etc.
Where does melanin originate from? What’s its function?
Melanin originates from tyrosine. Its involved with color of hair, eyes, and skin
Where do the catecholamines originate from? What’s their function?
Catecholamines: dopamine, norepinephrine and epinephrine originate from tyrosine. D is a NT and rewards the brain. NE and E are our fight or flight responses.
What is the essential enzyme involved in the production of T3 and T4? What is it’s specific function? A dysfunction in this enzyme results in what?
Thyroid peroxidase and its function is to convert iodide to iodine.
A dysfunction in this enzyme results in hypothyroidism bc the iodide is never converted to go and attach itself to the protein.
Describe homocystinuria. What are the clinical consequences?
Homocystinuria is an autosomal recessive defect in the cystathionine synthase enzyme which converts homocystine –> cytathionine –> cysteine, which is an essential amino acid for the body. As a result, homocysteine and other toxic byproducts build up in the body.
Clinical consequences:
1. blood clots in brain and lungs
2. Elevated risk for heart disease and arteriosclerosis
3. Damage to vascular endothelium and smooth muscle.
Describe phenylketonuria (PKU). What are the clinical consequences?
PKU is an autosomal recessive defect in the phenylalanine hydroxylase enzyme preventing the conversion of phenylalanine --> tyrosine. Causing an increase and phenylalanine and deficiency in tyrosine. Remember, many tyrosine is the originator of many mediators used by the body. Clinical consequences: 1. Mental retardation 2. light skin 3. fair hair 4. Poor memory 5. Difficulty with concentration
What enzyme can convert creatine –> phosphocreatine and be used to diagnose MIs?
Creatine kinase!
What is the result of a spontaneous reaction from phosphocreatine and what can it measure?
Creatinine! And can be used to measure renal function (more specifically glomerular filtration rate)
Remember glutathione? What does it’s reduced form do?
Glutathione (GSH) protects cells from oxidative damage from toxic peroxides.
What two enzymes does lead poisoning inhibit?
Lead Poisoning
- Delta-aminolevulinic dehydratase (ALAD)
- Ferrochelatase
