Lipid Metabolism

Which enzyme(s) catalyze the liberation of fatty acids from triacylglycerol?

TG Lipase, DAG lipase, and MAG lipase

When TG lipase is phosphorylated, is it activated or inhibited?

activated

What effect does epinephrine and glucagon have on lypolysis?

they stimulate it

Which lipolysis enzyme(s) is/are hormone sensitive?

TG lipase

Which lipolysis enzyme(s) is/are NOT hormone sensitive?

DAG and MAG lipase

What enzyme activates the conversion of fatty acids → fatty acyl-CoA

Acyl-CoA synthase

Is energy required for fatty acid activation?

yes

Where does fatty acid activation occur?

the cytosol

What is the rate limiting step of fatty acid oxidation/lipolysis?

the transfer of fatty acyl-CoA from the cytosol to the mitochondria

What does the carnitine shuttle system do?

facilitates the transfer of fatty acyl-CoA to the mitochondria

What is the rate limiting enzyme of fatty acid B-oxidation?

Carnitine acyltransferase I

What enzyme catalyzes the transfer of fatty acyl to carnitine?

Carnitine acyltransferase I

What enzyme catalyzes the transfer of fatty acyl to SH-CoA?

Carnitine acyltransferase II

What are the products of one cycle of B-oxidation?

1 FADH2, 1 NADH, 1 Acetyl-CoA

What are the steps of B-oxidation?

oxidation, hydration, oxidation, cleavage

What conditions stimulate the formation of ketone bodies?

starvation and diabetes

Where must citrate move in order for fatty acid biosynthesis to occur?

from the cytosol to the mitochondria

What two molecules are required for fatty acid synthesis?

Acetyl-CoA and malonyl-CoA

What is the committed step of fatty acid biosynthesis?

conversion of acetyl-CoA to malonyl-CoA

What is the rate limiting enzyme for fatty acid biosynthesis?

Acetyl-CoA Carboxylase (biotin)

What is acetyl-CoA bound to in the priming steps of fatty acid synthesis?

Ksase

What is malonyl-CoA bound to in the priming steps of fatty acid synthesis?

ACP

What are the steps of fatty acid biosynthesis?

Condensation, Reduction, Dehydration, Reduction, Translocation

What happens when Acetyl-CoA Carboxylase I is phosphorylated?

it is inactivated

How is lipolysis regulated?

high concentrations of malonyl-CoA inhibits carnitine acyltransferase I

What is the precursor for triacylglycerol and glycerophospholipid synthesis?

phosphatidate

How is phosphadiate produced?

fatty acids are transferred to GAP

How are triacylglycerols synthesized?

phosphate is removed from phosphadiate, and a fatty acyl-CoA is added to diacylglycerol

How are glycerophospholipids synthesized?

through the activation of alcohol and the addition of activated alcohol to phosphadiate

How can alcohol be added to phosphadiate?

through the linkage of diacylglycerol to CDP or the linkage of alcohol to CDP

What is the rate limiting step for cholesterol synthesis?

conversion of HMG-CoA → mevalonate

What is the rate limiting enzyme for cholesterol synthesis?

HMG-CoA reductase

What are the steps for cholesterol synthesis?

acetate → mevalonate → geranyl pyrophosphate → farnesyl pyrophosphate → squalene → cholesterol