Amino Acid Metabolism Flashcards
(23 cards)
Essential Amino Acids
- Must be obtained from the diet
- Can’t be synthesized by the body
- 9 total
- Methionine
- Threonine
- Valine
- Histidine
- Isoleucine
- Phenyl-alanine
- Tryptophane
- Leucine
- Lysine
Nonessential Amino Acids
- Can be synthesized in suffieicnt amounts from the intermediates of metabolism or from essential AA
- 11 total
*
Synthesis of Nonessential AA
(from where)
- All nonessential AA (except tyrosine) are sunthesized from common intermediates that are part of the TCA cycle
- Pyruvate
- Oxaloacetate
- a-Ketoglutarate
Synthesis of L-Tyrosine
- Formed from an essential AA
- L- Phenylalaine
Transamination
- Transfers an amino group to a ketoacid to form new amino acids
- Catalyzed by aminotransferases
Deamination
- Removal of an amine group from an amino acid
- Catalyzed by deaminases
AA used for the brain
- Glutamate
- Brain produces glutamine
- Nervous systems makes about 40 NT’s with nitrogen derived AA’s
*
Products of AA’s
Tyrosine –> Thyroid hormones, Melanin
Tryptophan –> Serotonin, Melatonin, Niacin
Arginine –> Nitric Oxide
Glutamate –> GABA
Histidine –> Histamine
Degradation of AA’s
(Catabolism)
- Glucogenic
- Ketogenic
Glucogenic AA’s
- Catabolism of AA produces pyruvate or one of the intermediates of the TCA cycle
Ketogenic AA’s
- Catabolism yields acetoacetate
- Acetyl CoA
- Acetylacetyl CoA
Pyruvate is converted to glucose via _______
Gluconeogenesis
The TCA cycle is integral in linking these 3 important pathways
- Carbohydrate Metabolism
- Amino Acid Metabolism
- Fatty Acid Metabolism
Final common pathway
Central role in gluconeogenesis & lipogenesis
The catabolism of ketogenic amino acids gives rise to _____ and _____.
Acetoacetate and acetyl CoA
The catabolism of glucogenic amino acids yields ______ or ______.
Pyruvate or one of the other intermmediates of the TCA cycle
The final breakdown product of all amino acids, releases the following toxic compound into cells:
Ammonia
In the skeletal muscle, what is the primary final produce of glycolysis?
Lactate
During the fed state, blood glucose levels _____, insulin ____ and glucagon goes ____.
- Blood glucose increases
- Insulin increases
- Glucagon decreases
Discuss the tissue inter-relationships in the fasting state.
- High glucagon levels
- Glycogenolysis occurs in the liver and brain
- RBC’s use the glucose released
- Adipocytes release free fatty acids and glycerol from stored triglycerides
- Will be used by the muscles for energy
- Liver converts the FFA to ketone bodies that are used by the brain and muscle as a source of energy
- Protein in the muscle is broken down
- travels to the liver for gluconeogenesis
- Ammonia generated enters the urea cycle for excretion
- Lactate made by RBC’s and glycerol from the adipose are also used for gluconeogenesis
Discuss the tissue inter-relationships in the fed state.
Plasma:
- Increased insulin and bile acid
Liver:
- Transcriptional regulation = decreased bile acid synthesis and gluconeogenesis
Blood glucose increases, insulin released, and glucagon levels decrease
- Fats and proteins are absorbed in the intestine
- Stimulates liver to store glucose as glycogen
- Can also break into Acetyl Co-A to make triglycerides
- Glucose is used up by the brain and by RBC’s to release energy
- Brain uses glucose and breaks into acetyl CoA to form TG
- RBC’s use pyruvate to break down lactate
- Glucose and VLDL’s are stored as TG in adipose tissue
- Will store as glycogen in the muscle if the TCA cycle can’t use it
- Insulin stimulates the uptake of AA’s and protein synthesis
