Nitrogen Metabolism Flashcards
What is happening to proteins in the body
Continually broken down and re synthesised
What is nitrogen a substrate for? (6)
Nucleic acid
Porphryin in heme
Thyroxine hormone
NT
Phospholipids
Coenzymes
What happens to AA break down
Energy
Fatty acid and glucose stores - involved in TCA
Production of AA
What can phenylalanine be converted to
Tyrosine
What is a key function of nitrogen
Enzymes
Most important nitrogen enzyme
Glutamate dehydrogenase
What does glutamate dehydrogenase do
Detoxifies material
Ammonia
Pathway of glutamate dehydrogenase
Ammonia
+
Alpha ketogluterate
To
Glutamate
+ water
NADH H+
Converted to
NAD
What 2 enzymes are involved in exertion of urea involving CNS
Glutamine synthase
Glutaminase
Pathway of glutamine synthase
Glutamine + NH4 + ATP
Goes to
Glutamate
+ ADP
Pathway of glutaminase
Glutamine
To glutamate
And ammonia
What is a transaminase
Enzyme which transfers an amine group from AA to an
Keto acid
What is a Keto acid
Contain ketone group and carboxylase acid group
Involved in TCA cycle
What are common transaminase acceptors/donor
Alanine
And
Alpha ketogluterate
Or
Aspartate
And
OAA
How are AA (non essential) formed
Transaminase reactions
May require processing before or after
Where do Keto acids derive
Intermediate metabolism
TCA glycolysis
What is produced from transaminase reaction when amine group placed on Keto acid
Keto acid converted to another AA
Are transaminase enzymes specific to the AA
Yes
Eg
Aspartate transaminase
What are common Keto acids
Pyruvate
Oxaloacetate
Alpha ketogluterate
Ribose 5 phosphate
What happens to AA when broken down
Amine group removed
Goes into urea cycle
Carbon skeleton reused in metabolism
Steps of degradation
Of amino acid
1 removal of amino group
- transaminase
2 amino group on new AA is recycled or goes to urea cycle
3 carbon skeleton enters intermediate metabolism
(TCA)
Glucogenic AA
Can be used to produce glucose by gluconeogenesis
What can glycogenic
AA intermediates are there for gluconeogenesis
Pyruvate
OAA
Fumarate
Propionyl CoA - succinate
Alpha ketogluterate
What do ketogenic AA form
Acetyl CoA
And
Ketones
Can acetyl CoA be converted to glucose?
No
What happens to ketogenic AA when broken down
Form acetyl CoA
- goes to ketones or ATP or fatty acid
Ketone bodies form
Where are AA stored
They’re not
Effects of ammonia toxicity
Neurological disease due to build up ammonia
Increased pH causes neuro problems
What does high ammonia stimulate
Why is this a problem
Glutamate dehydrogenase
But removed
Alpha ketogluterate
Which interrupts TCA cycle
ATP reduced
Death
Why are ammonia levels high in the CNS
Neurotransmission produces
Ammonia as byproduct
How is ammonia removed and excreted from CNS
Glutamine synthase
And
Glutaminase
What is important abou glutamine
Can pass through blood brain barrier
How are ammonia levels high in muscle after exercise
ATP goes to
AMP
Which goes to
Inosine MP and NH4
What enzyme is important in muscles to remove NH4
Glutamate dehydrogenase
What happens to lactate from post exercise
How is this product removed
Converted to Pyruvate
Transaminase reaction takes place
See sheets
Ammonotelic
Fish release nitrogen into environment
Release free ammonia
Uricotelic
Bird
Nitrogen
- produce uric acid
Bird poo
Insoluble crystals
Ureotelic
Urea highly soluble
Water loss
Urea cycle where
Liver
Mitochondria
And cytoplasm
Does urea cycle need energy
Yes
