fatty acid oxidation

acetyl Coa produced from fatty acids may be completely oxidized to

CO2

B oxidation

oxidation of fatty acyl group at C-3

B oxidation occurs after

the carboxyl group at C-1 is activated by attachment to coenzyme A

dietary fats are absorbed where?

small intestines

apolipoproteins

proteins in their lipid free form that bind lipids to form lipoproteins

what do apolipoproteins target

target triacylglycerols, phospholipids, cholesterol, and cholesteryl esters for transport between organs

chylomicrons

particles consisting of triacylglycerols, cholesterol, and apolipoproteins

lipoprotein

spherical aggregates of apolipoproteins and lipids

how are lipoprotein particles arranged

hydrophobic lipid at core and hydrophilic protein side chains

why is HDL dense

it is packed with protein

why are LDL and VLDL light

they are packed with fat

mobilization occurs when hormones_________signal the need for metabolic energy

glucagon and epinephrine

PKA triggers changes that

open the lipid droplet to the action of three cytosolic lipases

free fatty acids, FFAs

fatty acids released by lipases

what type of bond is serum albumin

noncovalent

serum albumin

blood protein that noncovalently binds and transports FFAs to target tissues

serum albumin

makes up ~½ of the total serum protein

what type of reaction does tricylglycerol undergo and by what enzyme

hydrolysis by enzyme triacylglycerol lipase

What happens to triacylglycerol after it hydrolyzes

Fatty acids are transported and metabolized by b oxidation Glycerol is metabolized through glycolytic pathway

glycerol kinase phosphorylates glycerol to form

glycerol 3 phosphate

three long-chain fatty acids

most of the biologically available energy of triacylglycerols resides in

how long are the fatty acids that the carnitine shuttle transports

14+

carnitine shuttle requiers what

fatty acyl CoA and carnitine

what 2 products does glycerol kinase produce after it phosphoryaltes glycerol

ADP and Glycerol 3 phosphate

Fatty Acyl-CoA Synthetase

iactivate the fatty acid by conversion to fatty acyl-CoA thioesters

where does fatty acyl Coa Synthase occur

isozymes present in the outer mitochondrial membrane

where are fatty acids activated and transported to

mitochondria

what steps does fatty Acyl-CoA Synthetase use

the hydrolysis of the pyrophosphate created and the two-step formation of the fatty acyl-CoA derivative

glycerol 3 phosphate dehydrogenase

central carbon’s OH group is oxidized to a ketone

after glycerol 3 phosphate dehydrogenase oxidizes what does it produce?

NADH+H and DHAP

fatty acyl CoA

contains a thioester linkage between the fatty acid carboxyl group and the thiol group of coenzyme A

how is the formation of fatty acyl CoA made more favorable

hydrolysis of 2 ATP bonds

Where is carnitine attached to fatty acyl CoA

in the cytosol

CAT 1

catalyzes a transesterification reaction to transiently attach a fatty acyl CoA to the hydroxyl group of carnitine to form fatty acyl carnitine

Where does CAT 1 take place

cytosol

acyl-carnitine/carnitine cotransporter

allows the passive transport of the fatty acyl-carnitine ester

where does the acyl-carnitine/carnitine cotransporter move 1 carnitine into

intermembrane space

where does the acyl-carnitine/carnitine cotransporter move 1 fatty acyl carnitine

into the matrix

where does CAT 2 take place?

inner face of the inner mitochondrial membrane

carnitine acyltransferase 2 (CAT2)

transfers the fatty acyl group from carnitine back to coenzyme A to regenerate fatty acyl-CoA and free carnitine

in what form does glycerol enter glycolysis

dihydroxyacetone phosphate

β oxidation

fatty acids undergo oxidative removal of successive two-carbon units in the form of acetyl-CoA

catalyzes the dehydrogenation of fatty acyl-CoA to yield a trans-∆2 enoyl-CoA

acyl-CoA dehydrogenase

enzyme that helps in formation of FADH2

acyl-CoA dehydrogenase

The Oxidation Catalyzed by Acyl CoA Dehydrogenase Is Analogous

Succinate Dehydrogenation

why is The Oxidation Catalyzed by Acyl CoA Dehydrogenase Analogous to Succinate Dehydrogenation

have FAD electron acceptor , bound to inner membrane , double bond is introduced into a carboxylic acid between a and b carbons

enoyl-CoA hydratase

catalyzes the addition of water to the double bond of the trans-∆2-enoyl CoA to form L-β hydroxyacyl-CoA

β-hydroxyacyl-CoA dehydrogenase

catalyzes the dehydrogenation of L-β hydroxyacyl-CoA to form β-ketoacyl-CoA

β-hydroxyacyl-CoA dehydrogenase is specfic for

L stereoisomer

what is β-hydroxyacyl-CoA dehydrogenase analogous to

malate dehydrogenase reaction of the citric acid cycle

what coenzyme does β-hydroxyacyl-CoA dehydrogenase form

NADH

acyl-CoA acetyl transferase (thiolase)

catalyzes the reaction of β-ketoacyl-CoA with coenzyme A to cleave into a free acyl CoA and a fatty acyl-CoA shortened by two carbons

Cleavage of the β-Ketoacyl-CoA is a

reverse Claisen condensation

the first three reactions in B oxidation convert the stable single bond between methylene groups

to a less Stable C-C bond

function of B carbon that makes it good for nucleophilic attack

ketone function on C-3

the terminal –CH2–CO–S-CoA

good leaving group that facilitates breakage of a-b bond

How to get acetyl CoA produced

to get the acetyl CoA produced in a reaction get the number of carbons and divide by 2

get FADH and NADH produced

To get the NAD or FADH produced in a reaction get the number of carbons and divide it by 2. Whatever you got from there subtract it by 1

each pass through the first stage of B oxidation produces

1 acetyl CoA , 2 pairs of Electrons and 4 Hydrogens

Where does FADH donate its electrons to

ETF

where does NADH donate its electrons to

mitochondrial NADH dehydrogenase

1 NADH produces how much atp

2.5

1 FADH2 produces how much atp

1.5 atp

each pair of electrons transferred from NADH or FADH2 to O2

O2 yields one H2O ("metabolic water")

reduction of O2 by NADH consumes

1 H per NADH

how much atp in 1 round of b oxidation

4

to get atp from b oxidation

carbon amount diveded by 2 subtracted by 1 and then multiplied by 4

to get atp from TCA cycle

(carbon amount divided by 2)*10

Oxidation of Unsaturated Fatty Acids Requires

enoyl-CoA isomerase and 2,4-dienoyl-CoA reductase

2,4-dienoyl-CoA reductase

reduces cis double bonds

enoyl-CoA isomerase

(converts cis double bonds to trans)

oxidation of a monounsaturated fatty acid requires

enoyl-CoA isomerase

∆3,∆2- enoyl-CoA isomerase

isomerizes the cis-∆3-enoyl-CoA to the trans-∆2-enoyl-CoA

ketone bodies

acetone, acetoacetate, and D-β hydroxybutyrate

ketone bodies are formed

from acetyl-CoA in the liver

acetone is

exhaled

transported to extrahepatic tissues and converted to acetyl-CoA

acetoacetate and D-β hydroxybutyrate

accelerates formation of ketone bodies

the accumulation of acetyl-CoA

extrahepatic tissues do not have the capacity

to oxidize them all

thiolase in keto formation

condensation of two acetyl-CoA molecules to form acetoacetyl CoA

why can thiolase run in both cleavage and condensation

lots of fatty acyl CoA = cleavage , lots acetyl coa = condensation

HMG-CoA synthase

condensation of acetoacetyl-CoA with acetyl-CoA to form β hydroxy-β-methylglutaryl CoA (HMG-CoA)

HMG-CoA lyase

cleavage of HMG-CoA to free acetoacetate and acetyl-CoA

acetoacetate decarboxylase

catalyzes the decarboxylation of acetoacetate to acetone

D-β-hydroxybutyrate dehydrogenase

reduction of acetoacetate to D-β-hydroxybutyrate

β-ketoacyl-CoA transferase

catalyzes the activation of acetoacetate

D-β-hydroxybutyrate dehydrogenase

catalyzes the oxidation of D-β hydroxybutyrate to acetoacetate in extrahepatic tissue

Ketone Bodies Are Used as Fuels in all Tissues Except and why

liver because it lacks -ketoacyl-CoA transferase also produces ketone bodies

Ketone Bodies Are Overproduced

Diabetes and during Starvation

acidosis

lowered blood pH

acidosis

can be caused by increased levels of acetoacetate, and D-β-hydroxybutyrate

ketosis

high levels of ketone bodies in the blood and urine

ketoacidosis

condition when ketosis and acidosis are combined

Individuals with Untreated Diabetes Have High

Acetone

acetoacetate decarboxylase

catalyzes the decarboxylation of acetoacetate to acetone

individuals with untreated diabetes produce large quantities of

Acetoacetate

acetone is formed from the decarboxylation of

acetoacetate

imparts a characteristic odor to the breath

acetone