CHE 4342 EXAM PRACTICE QUESTIONS
AND 100% CORRECT ANSWERS!!
Where does glycogen synthesis occur?
In the liver and muscles
From what end of glycogen is energy released from?
The non reducing end alpha (1->4)
What is significant about adding a phosphate to glycogen and creating G1P
It is highly exergonic
Why are there lots of branches on glycogen
so there are many non-reducing ends
What is the EC classification of glycogen phosphorylase?
2
What cofactor is needed to break down glycogen?
P5P, PLP pyridoxal-5-phosphate, vitamin B6
What kind of curve occurs when an enzyme has allosteric regulation?
sigmoidal
What kind of bond connects lysine to PLP
covalent
What is PLP used for in glycogen phosphorylase reaction
It is used in general acid catalysis
What is significant about the oxonium in the glycogen phosphorylase mechanism
it is an unstable half chair confirmation
, When the lysozyme reacts with the half chair in the glycogen phosphorylase mechanism
what does it form
a general base
What is the name of the inhibitor for glycogen phosphorylase and what does it resemble?
1,5-gluconolacetone, it resembles the lactone/transition state
What drives the reaction of glycogenolysis
inorganic phosphate
What does phosphoglucomutase do?
It converts G1P to G6P (EC:5)
What does UDP-glucose pyrophosphorylase do?
It converts G1P to UDP-glucose, it does a phosphoanhydride exchange
How does the glycogen branching enzyme work?
A 7 residue piece is removed from residue 6 and is transferred to a residue 4 down from original
branch
What is unique about glycogen
It is not just a carbohydrate it also has a protein core called glycogenin
Glycogenin has what amino acid that acts as the anchor for the reducing ends
tyrosine
How many UDP glucose molecules are added to each tyrosine
8
What does the enzyme fructose-1,6-bisphosphate do
F16BP to F6P
What are the three hormones in control of carbohydrate metabolism
AND 100% CORRECT ANSWERS!!
Where does glycogen synthesis occur?
In the liver and muscles
From what end of glycogen is energy released from?
The non reducing end alpha (1->4)
What is significant about adding a phosphate to glycogen and creating G1P
It is highly exergonic
Why are there lots of branches on glycogen
so there are many non-reducing ends
What is the EC classification of glycogen phosphorylase?
2
What cofactor is needed to break down glycogen?
P5P, PLP pyridoxal-5-phosphate, vitamin B6
What kind of curve occurs when an enzyme has allosteric regulation?
sigmoidal
What kind of bond connects lysine to PLP
covalent
What is PLP used for in glycogen phosphorylase reaction
It is used in general acid catalysis
What is significant about the oxonium in the glycogen phosphorylase mechanism
it is an unstable half chair confirmation
, When the lysozyme reacts with the half chair in the glycogen phosphorylase mechanism
what does it form
a general base
What is the name of the inhibitor for glycogen phosphorylase and what does it resemble?
1,5-gluconolacetone, it resembles the lactone/transition state
What drives the reaction of glycogenolysis
inorganic phosphate
What does phosphoglucomutase do?
It converts G1P to G6P (EC:5)
What does UDP-glucose pyrophosphorylase do?
It converts G1P to UDP-glucose, it does a phosphoanhydride exchange
How does the glycogen branching enzyme work?
A 7 residue piece is removed from residue 6 and is transferred to a residue 4 down from original
branch
What is unique about glycogen
It is not just a carbohydrate it also has a protein core called glycogenin
Glycogenin has what amino acid that acts as the anchor for the reducing ends
tyrosine
How many UDP glucose molecules are added to each tyrosine
8
What does the enzyme fructose-1,6-bisphosphate do
F16BP to F6P
What are the three hormones in control of carbohydrate metabolism
