Lipolysis, Fatty Acid Oxidation and Ketogenesis Flashcards
What is lipolysis? and what are lipase?
Fatty acids are mobilized from adipose tissue via activation of lipase through process called lipolysis.
They break the ester bonds of triglyceride (using water) to release fatty acids and glycerol.
What are the lipase within the adipocyte? What do they do?
- Adipose triglyceride lipase (ATGL), hormone sensitive lipase (HSL) and monoglyceride lipase (MGL) = adipose TG to FA
ATGL and HSL are highly regulated
What does Lipoprotein lipase do and where is it located? What about Pancreatic lipase?
LPL= Circulating TG to FA (in VLDL & Chylomicrons). LDL is located extracellularly on the capillary endothelium of adipose tissue.
Pancreatic Lipase= ingested TG to FA (and DG & MG)
What is Perlipin?
It is a protein surrounding the lipid droplet that positions and activates HSL & ATGL!
What are Free Fatty Acids (FFA) or Non-esterified fatty acids (NEFA)?
They are fatty acids that are circulating in plasma and bound to albumin.
What does CD36 do?
Converts Fatty Acid + ATP –> Fatty Acid Acyl-Coa
Can fatty acyl-CoA enter the mitochondria? When can it enter?
It cannot enter until it is converted to fatty acyl-carnitine by carnitine acyltransferase I
What inhibits CAT-I (carnitine acyltransferase I)?
Malonyl-CoA (generated by ACC).
What happens when glucose is readily available and glycolytic rates are high?
Malonyl-CoA will be abundant and fatty acids will not be oxidized!
When glucose is unavailable, malignly CoA levels will fall and fatty acid oxidation will increase!
What are ketone bodies useful for?
Can be utilized by muscle (heart and skeletal), and also can be made available to brain (which fatty acids are not, since FA cannot cross blood-brain barrier).
Ketogenesis only occurs in the LIVER!!!
What happens when OAA is low?
This means that glucose is relatively unavailable… So conversion of acetyl CoA to citrate is low and now you need to convert Acetyl CoA to acetoacetate and B-hydroxybutyrate
What do you need Monocarboxylate transporter (MCT1)?
Transports ketones and is used during ketone oxidation
What happens when you have an accumulation of ketones or a mutation in MCT1?
Can have metabolic acidosis (ketoacidosis)
Can glucose be synthesized from fatty acids?
NO!!!
