27 Ketogenesis

Definition of ketogenesis

synthesis of ketone bodies from acetyl coA

site of ketogenesis

mitochondria of liver cells

Starting compound of ketogenesis

Acetyl coA

Apa ketogenesis provide?

alternative form of E for the body

ketone body can make how many ATP?

22 ATP

ketone body is regulated by?

insulin

in a state of ketosis, what happened to ketone body production?

ketone body production increased.

Ini terjadi bila carbs decreased or increased fatty acid

what happened if too many ketone bodies accumulate?

ketoacidosis occur

Ketogenesis reaction pathway

Thiolase convert 2 acetyl coA to acetoacetyl coA

HMG CoA synthase convert acetoacetyl coA with acetyl coA to form HMG CoA

HMG CoA lyase split HMG CoA forming acetoacetate and acetyl coA

finally, acetoacetate is converted to D-3-hydroxybutyrate by D-3-hydroxybytyrate dehydrogenase

Liver cannot utilize ketone bodies as it lacks the ketolytic enzyme thiophorase. so how to utilize ketone body then?

ketone body are transported to extragepatic tissues like heart muscles, renal cortex, and brain to utilize energy

Regulation of ketogenesis

glucagon stimulate ketogenesis, insulin pula inhibit

ketone body formation is regulated at 3 levels

1. Lipolysis

2. entry of fatty acid to mitochondria

3. oxidation of acetyl coa

Ketolysis definition

breakdown of ketone bodies for energy

site of ketolysis

tissue site: heart muscle, renal cortex, skeletal muscle, brain HRSB

Intracellular site: Mitochondria

Ketolysis reaction

beta hydroxybutyrate dehydrogenase convert beta hydroxybutyrate to acetoacetate

acetoacetate succinyl CoA transferase convert acetoacetate to acetoacetyl CoA. dari ni rxn, succinyl CoA kena convert jadi succinate

acetoacetyl CoA kena convert pg 2 acetyl CoA guna enzyme beta ketothiolase dan ini perlu si CoASH

rate of ketone body synthesis

biasanya kalau ada ketone yang kena synthesis, extrahepatic tissue dapat juga metabolized dgn senang

Tapi bila ni synthesis exceed limit sebab byk ketone body, dia jadi ketosis

Ketosis constitute 3 clinical condition:

1. Ketonemia: Presence of high level of ketone bodies in the blood which is >1mg/ dL

2. Ketonuria: Excretion of large amount of ketone bodies in the urine (>100 mg/ day)

3. Acetone breath: Acetone us eliminated through the lungs giving acetone smell to the breath.

Condition where ketone body synthesis is increased and development of ketosis are

1. starvation

2. uncontrolled diabetes mellitus