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Biochemistry > FA Metabolism > Flashcards

FA Metabolism Flashcards

1
Q

Lipases in Body

A

lingual- small amt of fats
stomach- short chain
Pancreas- in duodenum, most fat, co lipase & BA= 2 monoacylglycerol

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2
Q

Lipoprotein lipase

A

outside endothelial & adipocytes. Chylomicrons & VLDL. Fat taken up by FA transport protein & CD36 or diffusion. LPL expression stimulated by insulin (adipose) and glucagon + epi in other tissues.

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3
Q

Adipose tissue triglyceride lipase ATGL

A

cleaves triacylglycerol to diacylglycerol & FA

Activated by PKA

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4
Q

Hormone sensitive lipase HSL

A

Cleaves triacylglycerol & diacylglycerol to FA & monoacylglycerol in adipocytes, I by insulin, stimulated by somatotropin, epi & glucagon using PKA
PKA aslo hyperP perilipins (non P= inhibit lipase access to lipid droplets)

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5
Q

Monoacylglycerol lipase

A

in adipocytes, cleaves mono acylglycerol into FA & glycerol
Glycerol transported to liver & enters glycolysis via glycerokinase & a glycerophosphate dehydrogenase
PKA activates it

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6
Q

FA degradation

A 
Short < 6 C
medium 6-12
long 14-24
very long >24 C 
most cells but not in nerve (can't cross BBB)
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7
Q

FA activation

A

Acyl coA synthetase (thiokinase) makes FA adenylate whichs then converts to acyl Co A using thiokinase AGAIN

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8
Q

Carnitine shuttle into mitochondrium

A

carnitine formed in liver & kidney from lys & met
<12 C atoms pass by diffusion
rate limiting step of FA breakdown

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9
Q

Systemic primary carnitine def

A 
renal re uptake transport OCTN2 (Na+) 
Hypoketotic hypoglycemia
Reye syndrome
Lethargy
HEpato & cardio megaly
Give carnitine orally
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10
Q

Carnitine palmitoyltransferase I def

A

hypoketotic hypoglycemia, Reye, heptaomegaly, m. weakenss

Prevent hypoglycemia with shorth & medium chain FA in diet

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11
Q

Carnitine acylcarnitine translocase def

A

presents w/in hours of birth
Seizures, bradycardia, breathing problems, sudden infant death
Low lipid intake, med chain FA, avoid excercise, carnitine

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12
Q

Carnitine palmitoyltransferase II def

A

Adult: m. problems, attacks during exercise, fasting, high fat diet, infection. Variable w/ age
Infantine- <1 yo, hypoketonic hypoglycemia, loss of consciousness & seizures
neonate- onset hours to days after birth, rapidly fatal. Neuronal migration defect

Low lipid intake, med chain FA, carnitine,avoid excercise
Bezafibrate- induce enz expression

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13
Q

Peroxisome Proliferator activated R

A

nuclear R proteins that bind FFA, eicosanoids etc. dimerize w/ RXR & control expression of increased number of peroxisomes.

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14
Q

Jamaican vomiting sickness

A

Posioning from MCPA-Co A inactivates carnitine acyl transferase I & II.
Short chain acyl CoA dehydrogenase also (NADH production)
Treat: supportive

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15
Q

B oxidation

A

occurs in mitochondrial matrix
Forms acetyl Co A from acyl CoA (which then gets reformed and recycled)

remove H to form 2x bond @ FADH2
add H2O to 2x bond
Reduce alcohol to ketone, form NADH
Make/break C-C on carbonyl C using coA- SH as energy

*can use w oxidation but not major pathway!

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16
Q

Unsaturated FA

A

problems in B oxidation
Cis double bonds
Use 3 additional enzymes to change 2x bonds from wrong direction

17
Q

Propionic Acidemia

A

defect in propionyl co A carboxylase, frequent in Mid east.
Vomiting, ketoacidosis, pancytopenia, hypogammaglobulineamia, protein intolerance
Treat: low protein diet

18
Q

Methylmalonic Aciduria CBL

A

Defect mitoch transport of B12 or defect conversion to adenyl form
Acidosis
Megaloblastic Anemia
Treat: B12

19
Q

Methylmalonic aciduria mut

A

acidosis only , no anemia
Sudden infant death
Therapy: nutritional manage, treat infections, carnitine

20
Q

SCAD

A

generalized or muscle only. Metabolic acidosis, fialure to thrive, dev delay, seizures, myopathy
NO HYPOGLYCEMIA

21
Q

MCAD

A

no FAD binding, after fasting or stress, fatal hypoglycemia (high gluconeogenesis, low KREBS), mitoch changes
Long term= slowed cognitive dev, cerebral edema, encephalopathy, no exercise, fatty liver
10% sudden infant death

22
Q

LCAD

A

usually with VLCAD

23
Q

VLCAD

A

missense mutations/deletions, some respond to bezafibrate.
Mem associated protein
Cardiomyopathy, non ketotic hypoglycemia, hepatic disf, sudden death
En handles upper 14-24 C not very long >24 C

24
Q

TFP

A

mitochondria tri functional protein
long change, hydroxyacyl Co A dehydrogenase & thiolase complex.
One is defective but rarely all 3 are.
Fulminant neonatal liver failure
Preg may lead to acute fatty liver of pregnancy in mother.

25
Q

ABCD1

A

adrenoleucodystrophy
ABCD proteins are ABC type half transporters forming dimers
Transport long & very long FA into peoxisome
X linked
Fail to metabolize VLCFA leads to accum in brain & adrenals= demyelinization of white matter= death in adolescence
Loss of vision, hearing, neuro Addison’s disease
Lorenzo’s Oil

26
Q

Zellweger Syndrome

A

Defect in peroxisome formation genes
Cerebrohepatorenal syndrome- facial features, polycystic kidneys, liver, CNS probls, chondral calcification, high Fe & Cu, elevated pipecolic acid
Type 1= disparity b/t serum & cell results
type 2= disparity in matrix protein import into peroxisomes in adj cells from same indivs
No cure!
Death w/in 1st half year

27
Q

Adult refsum disease

A

progressive cerebellar degenration & periph neruopathy, retinitis pigmentosa, cataract, ataxia, diff hearing
Caused by phytanoyl CoA dioxygenase or peroxin 7 mutations
Treat by restricting fish fat & plasmapheresis

28
Q

Ketone Bodies

A

Liver turns unneeded FA into ketone bodies
occurs when Glc supply is low
ketone bodies tranported by blood to target organs like m. , heart
Ketone body [ ] low to cross BBB
In long term starvation= 2/3 of brain E
Ketoacidosis= excess ketone bodies in urine

29
Q

FA syn

A

convert carb to fat via acetyl Co A

liver, milk glands, adipose tissue, kidney & lung

30
Q

Malate shuttle

A

acetyl co A in mitochondria from glucose, transported to cytosol for FA syn (1 ATP)
Malate dehydrogenase- oxaloacetate & NADH to malate & NAD+

Malic enz- malate & NADP+ to pyruvate & NADPH

Pyruvate carboxylase= pyruvate to oxaloacetate & ADP

31
Q

Pyruvate Carboxylase Def N Amer group

A

lactic, pyruvate & alanine acidemia
Severe metnal, psychomotor & dev retardation
Inactive enz
Treat with thiamin, lipoate & dichloroacetate to utilize PDH

32
Q

Pyruvate Carboxylase Def French

A

resp distress, increased serum, lactate, ammonia, pro, lys
intracell redox distrubance
cytosolic more red than mitoch which is more ox
don’t survive past 3 months
No enz

33
Q

Pyruvate Carboxlase Def Benign

A

preservation of motor & metnal abilities
metabolic acidoss w/ elevated lactate, pyruvate, alanine etc. (rehydrate & bicarb)
Anemia with increased reticulocytes
R shift O2 curve due to increase in 2,3 BPG

34
Q

FA synthesis

A

empty enz rechard w/ acetyl Co A
Enzy contains 4 phosphopantetheine as acyl binding & cys SH
syn like B ox but w/ NADPH
in cytosol
reducing from PPP & malic enz
acetyl coA carboxylase I by palmitate & cAMP, stim by citrate

unsat FA & insulin decrease acetyl Co A carboxylase & FA synthase

35
Q

Polyketide

A

acetyl or propionyl Co A condensed w/ malonyl or methylmalonyl co A
Gets additional modification (cyclization, methylation)
Used as antibiotic, chemotherapuetic, immunosuppresant
Erythromycin, amphotericin etc.

36
Q

Elongation & desaturation

A

FA activated to acyl co A, then react with malonyl co A

Then oxidase introduces OH groups, H2O removal to form 2x bond on some C

37
Q

Regulation

A

FA syn & B oxidation must not occur at same time.
FA syn in cytosol, breakdown in motchondria
Malonyl Co A shuts down carnitine shuttle
FA syn regulated @ acetyl co A carboxylase:
citrate allosteric
insulin: deP, activation
glucaon & epi- increase cAMP- increase P- inactivation
gene expression- more insulin, less glucagon

Biochemistry (8 decks)

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