Lightbody Lecture 12 Flashcards Preview

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Flashcards in Lightbody Lecture 12 Deck (37):
1

E stores in typical body

135000kcal fats (85% of body's stored E), 24000kcal prot, 720kcal glycogen, 80kcal blood glucose (gluc can last 1 day)

2

beta oxidation

ox of FAs; takes place in mito matrix; FAs broken down into 2C frags (aCoA) which enter TCA or conv to ketone bodies in liver

3

ATGL - adipocyte TAG lipase

hydrolyzes only TAG

4

HSL - hormone sensitive lipase

hydrolyzes TAG and DAG; + by isoproteronol (stims adren receps), + by phos by PKA and PKG (translocates from cyto to perilipin-cont droplets, - by insulin)

5

MGL - monoglyceride lipase

hydrolyzes only MAG

6

acyl CoA synthetase

takes R-COO- FA and ATP, becomes acyl-adenylate intermed, then use again w/CoASH to become acyl-CoA + AMP

7

key process in fat metab

hydrolytic cleavage of stored TAG w/gen of FA and glycerol and their release from adipocytes where they're transported, complexed w/albumin, to various tissues to be used as E

8

perilipin

coats lipid droplets in adipocytes; acts as protective coating agst lipases; non-phos (coats lipid droplet) or phos (by PKA and PKG, changes conf, exposing stored lipids to HSL)

9

carnitine acyltransferase I

in carnitine shuttle; - by malonyl CoA, makes O-acylcarnitine from L-carnitine, then O-acylcarnitine gets translocated and acyls transferred to move L-carnitine into cell

10

FA activation

after leave adipocytes, transported (att to albumin) to other tissue (m, heart, liver); short and med chain (<12) can x mito memb, activated in matrix; long (12-20) activ at outer mito memb, transported into mito by carnitine shuttle

11

b-oxidation

dehydrogenase w/FAD as e- acceptor, then hydration, then dehydrogenase w/NAD as e- acceptor, then cleave CC bond (thiolase)-->acetyl-CoA and new fatty acyl-CoA w/2 fewer C units

12

b-oxid of palmitic acid (C16)

7 cycles; 131-2 = 129 ATP from activation; in mito matrix

13

2 mito systems of b oxidation

1) fam of memb-bd enz's spec for long-chain FAs; 2) soluble enz's in matrix spec for short and med chain FAs; as long shortens, moves from memb-bd complex to soluble matrix enz's (maj of FAs entering mito are long-chain)

14

metab of odd-chain FAs

propionyl-CoA-carboxylase->D-methylmalonyl-CoA-racemase->L-methylmalonyl-CoA-mutase->succinyl-CoA-->TCA

15

oxid of unsat FAs

almost all unsat FAs cont only cis DBs; hydratase acts only on trans, so need isomerase (oleoyl-CoA; eventually become acetyl-CoA, but need an isomerase to make cis-->trans, then use hydratase

16

carnitine cycle mito fat oxid disorders

involves LCFA transport thru inner mito memb

17

disorders of mito fat oxid in general lead to

cardiomyopathy, hypoglycemia, hypokeosis, myopathy, encephalopathy; defs in carnitine cycle or inner memb can be partially overcome by giving MCFA or SCFA (milk)

18

inner memb sys mito fat oxid disorders

mainly shortening of LCFAs thru b-oxid

19

mito matrix fat oxid disorders

oxids FAs of shorter length, doesn't involve carnitine

20

artificially induced trans fatty acids

hydrogenate polyunsat cis oils-->bonds that don't reduce change from cis to trans (margarines) - not oxidized easily, so reduce rancidity, inc shelf life; cont no animal fats; raise LDL, lower HDL; contrib to coron heart dis, cancer, diab, obesity, liver dysfxn

21

ketone bodies

FAs metab to acetyl-CoA by b-ox, then condense to form KBs; synth ONLY in liver mito; secreted into blood, transported to other tissue (heart, m, kidney, brain), reconv to acetyl-CoA, used as E; liver cannot metabolize them!; synth small quant all the time, but in starvation, unctrl'd diab I synth in lg quants

22

synth of ketone bodies

acetyl-CoA-->acetoacetylCoA-->3-hydroxy-3-methylglutaryl-CoA (HMG-CoA--also in chol synth)-->acetoacetate-->acetone + b-hydroxybutarate

23

metab of ketone bodies

water sol equiv of FAs; brain can use in starvation

24

thiophorase

needed to metab KBs; liver deficient in this, so can only synth, not metab!

25

fasting, starvation, severe T1D

OAA (via malate) leaves mito, used for glucose synth (GNG)-->shuts down TCA; at time, liver prod A-CoA by b-ox of FAs, but has nowhere to go, so condenses to KBs; glc levels maint by glycerol, RBC lactate, AA brkdn (major source)

26

KB utilization

rel into systemic blood (acetone elim in urine, exhaled; acetoacetate and b-hydroxybutarate used as fuels); convert to E (b-hydroxybut and acetoacetate conv to acetoacetyl CoA using succ CoA from TCA; cleaved to 2-acetyl-CoA); range of tissues can use (brain when starved, thiophorase induced after 4d of starvation, derive 50% of E from KB); excess-->acidosis, relieved thru elim of KBs thru urine

27

Atkins

high fat, low carbs-->fat mobil and KBs in urine; active fat metab and GNG; check for KB in urine-->sign that fat metab; discouraged b/c metabolic acidosis

28

KBs and T1D

diab-->high glc in blood; transport into tissues reduced; resp by inc GNG in liver, inc TAG brkdn in adipocytes; FAs transp to liver for ox, consuming most of OAA; no OAA, so excess a-CoA condenses-->KBs (detect acetone on breath)

29

peroxisomes

synth bile acids, lipids, H peroxide, detox; live a few days; brkdn VLCFAs (C22-30), both sat and unsat; cont all b-oxid enz's (enz that activates VLCFA (acylCoA synthetase) only in this organelle); have sep transporter, so don't need carnitine; b-oxid only goes a few cycles, then rel'd to mito for further oxid

30

catalase

degrades H2O2 in peroxisome; 2H2O2-->2H2O + O2; don't prod ATP

31

FADH2 in peroxisome

gen'd by b-oxid; reox-->H peroxide; difers from mito where this enters e-transport chain (FADH2 + O2 --> FAD + H2O2)

32

NADH formed in peroxisome

can't be reox here, so has to be exported out

33

A-CoA formed in peroxisome

must transfer out b/c TCA cycle enz's absent

34

X-ALD

dec in abil for peroxisomes to degrade VLCFAs, so build up in adrenal, brain, plasma, fibroblasts-->interfere w/abil of adrenal to conv chol into steroid, demyelin nn in brain; appear @4-10yo (behav /\, bad vision, hearing, coord); death 2-4y later

35

X-ALD defect

ATP bdg ABCD1 transporter prot (ALDP), crucial for transport of VLCFAs into peroxisomes; treat w/Lor oil or stem cell therapy

36

Lorenzo's Oil

4:1 mix of oleic acid and erucic acid from olive and rapeseed oil; must give before symps present, low fat diet; retard disease (maj of VLCFAs accum are sat FAs from diet and synth)

37

elongase

synth saturated VLCFAs; elongates both sat and unsat FAs; monounsat FAs compete for this enz, lowering synth of sat VLCFAs