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bio archindonic

Leukotrienes and lipoxins

QuestionAnswer
How do leukotrienes differ from prostaglandins, prostacyclins, and thromboxanes? linear eicosanoids, not cyclic
What is the role of leukotrienes? mediate allergy response, immunity, inflammation
What is the most serious leukotriene that causes a response 10,000 times (5 orders of magnitude) greater than histamine? peptidoluekotriene
Peptidoleukotrienes are known to be the active component of what mediator of intense, violent, often fatal allergic rxns? slow-reacting substances of anaphylayxis (SRS-A)
What is the common predominant precursor between cyclic eicosanoids and linear eicosanoids? arachidonic acid
The first step of Arachidonic acid metabolism is it's conversion by what to what? Lipoxygenases (LO) convert it to 5HPETE: hydroperoxyeicosatetraenoic acids
What final products do the three types of lipoxygenases create? 5-LO = leukotrienes, 15-LO = lipoxins, 12-LO = hepoxilin
AFter conversion to 5-HPETE, what does 5LO create in it's second catalyzation? 5-HPETE to Leukotriene A4 - the parent leukotriene
What must also be present to assist 5LO? FLAP - 5-lipoxygenase activating protein
What are the two reactions of 5LO? adds Ox to arachidic acid to make 5-HPETE then, acts as endoperoxidas to remove water and create an double attached Oxygen, peroxy? which is Leukotriene, A4
What special trait does LTB4 exhibit? Chemotactic, attracts immune cells to fight infections
What important antioxidant is needed as a substrate for LTA4 to convert to other actives such as LTC4, LTD4, LTE4 glutathione via glutathion-S-transferase
What do LTC4 and LTE4 do? peptidoleukotrienes - they are the actual bad ones - SRS-A's of astma and inflamation
What is important about omega-3 fatty acids in our diet? They form eicosapentaenoic acid (EPA) prostaglandins and leukotrienes derived from them are less physiologically active - decreased inflammation etc..
What are the Series Number associated with prostaglandins and leukotrienes derived from arachadonic acid? Prostaglandins = series 2 Leukotrienes = series 4
What are the Series Number associated with prostaglandins and leukotrienes derived from eicosapentanoic acid (EPA)? Prostaglanidin = series 3 Leukotriene = series 5
What are the Series Number associated with prostaglandins and leukotrienes derived from eicosatrienoic acid (ETA)? Prostaglandins = series 1 Leukotrienes= series 3
PGH2 synthase is a multifunctional enzyme with two active sites. What operates at each? One = cyclooxygenase (COX) Two = endoperoxidase
How are lipoxins different from other eicosanoids? The are ANTI-inflammatory agents
How do we synthesize lipoxins? 15-LO
Why do we still think of arachidonic acid in terms of inflammation if it also makes lipoxins? Prostaglandin synthesis is greater than lipoxin synthesis.
How does aspirin over come the prostaglandin/lipoxin imbalance? Aspirin is a suicide inhibitor of the PGH2 pathway. It ihibits COX 1 and COX2, but does not inhibit endoperoxidase at the second active site on PGH2-synthase. So 15-HPETE can make 15-epi-LXA4, which is a version of lipoxin.
What are aspirin-triggered epilipoxins? enantiomers of 15S-HPETE formed when aspirin blocks the COX active site, but does not affect the endoperoxidase site on PGH2-synthatse
The pharmaceutical industry produces an agent that targets receptors How? inhibit release of arachidonic acid from phosphatidyl insositol by steriods that block Phospholipase A.
What drugs target leukotriene action by inhibiting LTC4-receptors? Montelukast (singular) Zarfilukast (Accolate)
What drug inhibits 5-LO? zileuton (Zyflo)
What drug inhibits FLAP MK0886
Created by: El Diablo on 2010-02-22



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