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Flashcards in AA Metaboilsm- week 4 Schmidt Deck (13):

Essential AA

PVT TIM HALL Pheylalanine (makes tyrosine) Valine Trypotophan Threonin Isoleucine Methionine Histamine Arginine (you can make ariginine, but not enough for growth in infants/children) Leucine Lysine


Discuss storage of AA

AA are usually not stored in the body so they must come from diet. IF not from diet then either de novo synthesis or recycling through degradation


Sturcutre of AA

ALpha Carbon attached to H, NH2, COOH, and an R gorup. The R varies in each AA and that's where the charge comes from. All AA are in the L-isomer except glycine because it has two H+ so it doesn't have a sterocenter


Where do we get AA from? How much from each source?

1. Diet (~100grams/day) 2. Degradation from own bodys protein (~400g/day) 3. Synthesis of AA-- varies Used for glucose, glycogen, ketone bodies, FA steroids, and biological molecules that contain N+


What side to most enzymes clip

Carboxyl end


What does the AA pool consist of

1. THe AA from the degradation of the body's proteins 2. THe AA from our diets that have left through the walls of the GI tract *through transport systems) and enter circulation


What happens when we aren't getting enough proteins in diet

It can lead to muscle wasting. When we don't get enough we rely on the source of AA from muscle to meet energy needs and this can lead to muscle wasting


Break down of proteins in GI

Stomach- HCl denatures protiens- unfolding Pepsin- breaks proteins into large fragments IN the SI trypsin (activated by the enterokinase of the SI) activates chymotrypsin, amono and carboxypeptidases. The resulting AA are absorbed by intestinal cells through AA specific transporters


General process of

AA from skeletal muscle are broken down and we transfer the aminoa on alanine or glutamine. THey are broken down in the liver releaseing the amnonia into the uric cycle. Where urea and glutamine can go to the kidney for excretion


Two ways of regulation of AA

1. Regulated synthesis- we get more by synthesizing more 2. Constitutive synthesis- synthesis is relatively constant and the seletive degradation process Total amount of protein should be relatively constant


Name the two ways of degrading proteins

What are the steps of the first?

Ubiquitin proteasome proteolytic pathway


1. Ubiquitin proteasome protoyltic pathway-- mainly intracellular proteins- requires ATP

2, Lysosomal protoelytic degradation- mainly extracellular, occurs at acid pH


1. Protein for degradation is tagged with 76 chain ubiquitin and this cost ATP

2. The cytolsic protreasomes recognize the ubiquitin and take in the protein in the their core were is is unfolded and degraded

3. Ubiquitin and AA are released and the ubiquitin is recycled




Eplain Cysturia

This is a common inherited disease and there is an error of AA transport. COAL (cystine, urithine, argine, and lysine are di basic) and there transporter is missing/defective so they build up in the proximal tubule of the kidney and since cystine is insoluble it starts to form stones that block the urinary tract 


Explain Hartups disease

This is a defect in the intestinal and renal absorptino of neutral AA. SO there is a deficiency in essential AA from the diet... Mainly trypotophan which is a precursor to melanin, serotonin, and naicin. 


HArtups patients have excess AA in urine and can be treated with B3 supplements- the deficienty in B3 causes pellegra- neuronal and skin problems