Protein/Urea Flashcards
What are the digestive enzyme release by the stomach?
What activates it?
Pepsinogen
Activated to Pepsin by HCL
What are the enzymes release by the pancreas?
Trypsin, Chymotrypsin, Proelastase (Elastase), Carboxy-peptidase.
What activates/unleashes the proteolytic cascade?
Enteropeptidase unleashes the proteolytic cascade, since it coverts trypsinogen into trypsin, by doing so unleashes a cascade of proteolytic activity, because typsin is the common activator of all pancreatic zymogens.
What bonds does trypsin cleaves?
Trypsin cleave in specifically Arginine and Lysine bonds.
What happens in Cystinuria?
It is the inability to reabsorb CYSTINE, which leads to accumulation and subsequent precipitation of stones of cystine in the urinary tract.
This is a disorder of the proximal tubule’s reabsorption of filtered cystine and dibasic amino acids. COAL ( cystine, ornithine, Arginine, Lysine). Hence we will see this AA in the urine.
How are free amino acids taken by enterocytes?
How are Di-and Tripepetides taken up?
They are taken up by Na-linked secondary transport system.
Di-and Tripepetides are taken up by a H-linked transport system. There, the peptides are hydrolyzed in the cytosol to amino acids before being released into the portal system.
Only free amino acids are bound in the portal vein after a meal containing protein.
What happens with defects in the transport of tryptophan (and other neutral amino acids)?
It can result in the Hartnup disorder, and pellagra-like (pellagra-deficiency in niacin causing diarrhea, dermatitis, mental disorders) dermatologic and neurologic symptoms.
What keeps Amino acids from oxidative breakdown?
Alpha-amino group keeps amino acids safely locked away from oxidative breakdown. Removing the alpha-amino group is essential for producing energy from any amino acid, and is an obligatory step in the catabolism of amino acids.
What happens in transamination?
This is the first step in the catabolism of most amino acids. It is the transfer of their alpha-amino group to alpha-ketoglutarate, thus becoming glutamate.
All amino acids, with the exception of two, participate in transamination at some point in their catabolism.
Which amino acids do not participate?
Lysine and Threonine.
What does ALT enzyme catalyses?
Alanine aminotransferase (ALT) enzyme catalyzes the transfer of the amino group of alanine to alpha-ketoglutarate, resulting in the formation of pyruvate and glutamate.
What does AST enzyme catalyses?
Aspartate Aminotransferase (AST) is an exception to the rule that aminotransferases funnel amino groups to form glutamate.
AST transfers amino groups from glutamate to Oxaloacetate (OAA), forming aspartate, which is used as a source of nitrogen in the urea cycle.
All aminotransferases require a coenzyme, which is covalently linked to the epselon-amino group of a specific lysine reside at the active site of the enzyme.
The coenzyme is?? A derivative of ??
The coenzyme is Pyridoxal phosphate, a derivate of vitamin B6.
What happens when plasma aminotransferases are elevated?
Normally there are low levels of aminotransferases in plasma. The presence of elevated plasma levels of these indicates damage to cells rich in these enzymes.
Plasma ALT and AST are elevated in nearly all liver diseases, but are particularly high in conditions that cause extensive cell necrosis, such as severe viral hepatitis, toxic injury, and prolonged circulatory collapse. (36hrs. after increase, billirubin increases as well).
What are the nonhepatic diseases where aminotransferases may be elevated?
Myocardial infarction and muscle disorders.
