Gluconeogenesis

Question 1

What enzyme does the CORI cycle use?

Answer 1

Lactate Dehydrogenase
Uses NADH in muscle, and NAD in liver

Question 2

What enzyme does the Alanine cycle use?

Answer 2

Alanine aminotransferase

Question 3

Describe the Alanine cycle mechanism

Answer 3

In muscle, glucose is turned into pyruvate, which is turned into alanine

The alanine is combined with ⍺KG to produce Pyruvate and Glutamate

The Glutamate is then combine with OAA to produce aspartate and ⍺KG

Once Alanine is produced, it is shuttle to the liver where the cycle works backwards

Question 4

How is the first irreversible step circumvented?

Answer 4

Pyruvate + ATP +CO2 -> OAA +ADP via Pyruvate Carboxylase

OAA + GTP -> PEP + GDP + CO2 via PEP Carboxykinase

Question 5

How is the second irreversible step circumvented?

Answer 5

F16BP + H2O -> F6P + Pi via F16Bisphosphatase

Question 6

How is the third irreversible step circumvented?

Answer 6

G6P + H2O -> Glucose + Pi via G6Phosphatase

Question 7

What gets added then removed during the creation of OAA in gluconeogenesis?

Answer 7

CO2 gets added, then removed before conversion to PEP

Question 8

What is the role of Acetyl-CoA in gluconeogenesis?

Answer 8

Activates Pyruvate Carboxylase, and signals a need for more OAA, for example during fasting

Question 9

How does Insulin inhibit gluconeogenesis?

Answer 9

It prevents adipose lipolysis, which then prevents FAs from being broken down into Acetyl-CoA

Question 10

What inhibits F16BPase?

Answer 10

AMP and F26BP (this in turn activates PFK1)

Question 11

Where does the GTP for PEPCK come from?

Answer 11

The conversion of Succinyl-CoA to Succinate