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24 Cards in this Set

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  • Back
What forms are lipids absorbed from the gut?
1.Short-Medium chain FA(C4-C12)
3.2 monoacylglycerols
5.Fat soluble vitamins
What is a chylomicron remnant?
The portion of a chylomicron that remains in the blood after LPL action is known as a chylomicron remnant.
What lipoproteins are associated with chylomicrons, VLDL and what are their roles?
1.B-48 – synthesized in intestine (lipid carrier)
2.B-100 – synthesized in liver (VLDL carrier)
3.Apoprotein CII – activates LPL
4. Apoprotein E – receptor recognizes the Chylomicron clearance
What is the significance of lingual and gastric lipases?
1.Lingual lipase – enzyme that starts to digest lipids in the mouth
2.Gastric lipases – enzyme that digest lipids in the stomach
3.Both active on short – medium chain FA & more active in children
What are the actions of pancreatic lipase and colipase?
1.Pancreatic lipase – binds to and digest triglycerides (hydrolyzes FA leaving 2 monoacylglycerol)

2.Colipase – links fat to lipase
Triacylglycerols formation / reformation in the intestinal epithelial cell or liver cell use slightly different start points or backbones. Liver uses glycerol and intestine epithelial uses ________?
Fatty acids and 2-monoacylglycerols are condensed by enzymatic rx to form triacyglycerols.
What is the relationship between apoB48 and apoB100?
•Both coded by the same gene (48% of 100)
•Structurally and genetically related
•Both are major apoproteins associated with chylomicrons
Which form of cyclooxygenase is generally thought of as an inflammatory inducible enzyme?
Prostaglandin mediates the inflammatory response
What enzymes play a role in eicosanoids synthesis?
•Cyclooxygenase – (Prostaglandins & Thromboxanes)
•Lipoxygenase – (Leukotrienes, HETE, & Lipoxins)
•Cytochrome P450 – (diHETE & HETE)
Oxidative stress is s component of many diseases. What urinary metabolite can give an indication of the level of this type stress?
•Isoprostane – radical damage to a phospholipids on arachidonic acid residue
What are some of the major actions of each of the classes of eicosanoids?
a.(PGI2, PGE2, PGD2)
Increase -Vasodilation, cAMP
Decrease -Platelet aggregation, Leukocyte aggregation, IL-1a and IL-2,
T cell proliferation, Lymphocyte migration

b. PGF2
Increase - Vasoconstriction, Bronchoconstriction, Smooth muscle contraction

2. Thromboxanes
Increases :Vasoconstriction, Bronchoconstrition, smooth muscle contraction.

3. Leukotrienes
Increases -Vascular permeability, T-cell proliferation, Leukocyte aggregation, INF, IL-1 & IL 2

b. LTC4 and LTD4
Increases - Bronchoconstriction, Vascular permeability, INF
What are the enzymes, their sources, mechanism of activation utilized in protein degradation?
1. Pepsinogen- (Stomach chief cells) precursor to Pepsin (endopeptidase cleaves next to aromatic or acidic acidic AA)
2. Exocrine pancreas secretions:bicarb plus several zymogens / trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase
3. Enteropeptidase – (Brush border) cleaves trypsinogen to trypsin which activate other zymogens.
4. Exopeptidase-(intestinal epithelial cells) aminopeptidase located on the brush border cleave one amino acid at a time
zymogens (for each, give what activates it, and active form name)
1. pepsinogen
2. trypsinogen
3. chymotrypsin
4. proelastase
5. procarboxypeptidase
zymogen, activates, active enzymes
1. pepsinogen, H+, pepsin
2. trypsinogen, enteropeptidase, trypsin
3. chymotrypsin, trypsin, chymotrypsin
4. proelastase, trypsin, elastase
5. procarboxypeptidase, trypsin, carboxypeptidases
Which protease are associated with lysosomal degradation, proteasome degradation, apoptosis etc
Table 37.2 Mark's Biochemistry
What are the sources of N in the urea cycle?
*Glutamine to Glutamine RX. Produces NH4
*Aspartate to Fumarate RX. Produces NH4
Asparagine to Aspartate RX produces NH4
Serine to Pyruvate RX produces NH4
Histodine to Urocanate produces NH4
*Glutamate to Ketoglutarate produces NH4
Bacteria in Gut produces NH4
(also refer to figure 38.5 in Mark's Biochemistry)
How are BCAA metabolized in the brain?
•Neurotransmitter synthesis all come from AA precursors
•Brain astroglial cells use BCAA for production of glutamine via glutamine sythetase
•NH4 is used from deamination of AA and AMP in brain purine cycle
•Glutamine passes to neural cells and supports GABA production
•Aspartate synthesized with Glutamine using amino groups donated by BCAA (mainly Valine)
Why is there a need for continuous protein synthesis? How is this need met?
Proteins have continuous turnover in the body, and have variable t ½ (ex. Hemoglobin, muscle proteins, digestive enzymes, intestinal epith. Cells)

Lysosomal protein turnover (autophagy)
Ubiquiutin – target intracellular protein for degradation
What is ubiquitous role in protein degradation?
Ubiquitin targets intracellular protein for degradation by covalently binding to the amino group of lysine residues. A proteasome complex called proteasome then degrades the target protein and releases the ubiquitin intact to be recycled.
What are PEST sequences? CAP proteins?
PEST sequences are used to help target protein frequently degraded by the Proteasome Pathway such as (Praline, Glutamine, Serine, and Threonine)

CAP proteins – alter the specificity of the proteasome
-(PA700) – required for ubiquinated proteins
- (PA28) – targets only short peptide to the complex
What AA are the major N transporters in blood?
1. Glutamine
2. Glycine
3. Dopamine
4. Norepi
5. Epi
6. Serotonin
8. Acetylcholine
An increase ammonia load would have what effect on the urea cycle?
The urea cycle is regulated by substrate availability, the higher the rate of ammonia production, the higher the rate of urea formation.
What enzymes are important to formation of glutamine and its metabolism / catabolism?
Glutamine synthetase – (Brain) converts Glutamate to Glutamine

Glutamate deydrogenase – (Gut, Kidney) converts glutamine to α- ketoglutarate to be converted to glucose and used as fuel for the gut or kidney

BCAA Transaminase – (Brain, Heart, Kidney, skeletal muscle) – transamination of BCAA to α- keto acids to be converted to Glutamine.
What are the uses of glutamine in hypercatabolic states such as trauma etc..?
Mobilization of fats, carbs and AA to supply energy to mount immune response and wound healing

Skeletal muscle protein synthesis decreases and degradation increases.
Immune system prioritized release of AA

Increase glutamine delivery for energy sparing glucose (may see mild hyperglycemia as result)

Cytokine and hormone mediation of AA flux

Increase epi release, glucagons and insulin.

Note: You should also recognize the importance of glutamine / glutamate pathways
In sepsis, what causes high insulin resistance?
epi and glucocorticoids