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Name the Essential Amino Acids.
Name the Non-Essential Amino Acids.
Name some Conditionally Essential Amino Acids.
How many amino acids does an Oligopeptide have?
Several amino acids
How many amino acids does a Polypeptide have?
From 50 amino acids
How many amino acids does a Protein have?
a few dozen to several hundred amino acids
What is protein denaturation?
It occurs when proteins are subjected to heat, acid or other conditions that disturb their stability.
This is accompanied by uncoiling of protein/amino acid structure, loss of shape and loss of function.
eg. hardening of an egg when cooked
Give 6 functions of protein giving an example for each answer.
- 1. As building materials for growth and maintenance.
- Example: The protein collagen is needed for building bones/ligaments/tendons/artery walls/scar tissue. Proteins are also needed for cell replacement in skin, muscle and GI tract.
- 2. As enzymes.
- Example: Digestive enzymes
- 3. As Hormones.
- Example: Tyrosine needed for thyroid hormones.
- Tyrosine needed for neurotransmitters. Tryptophan needed for melatonin.
- 4. As Immunoproteins/ Immunoglobulins/ Antibodies.
- Example: IgG, IgA, IgM, IgE, IgD etc
- 5. As Transport proteins.
- Example: Transferrin to transport Iron, Hemeproteins to tranport O2
- Albumin to transport Ca, Zn, VitB6
- 6. As acid-base regulators
- Example: Proteins have a negative charge and they attract hydrogen ions which have a positive charge. They can release them to maintain pH in body fluids such as stomach acid, saliva, semen, vaginal secretions, tears, sweat and blood.
- 7. As fluid base regulators.
- Example: Oedema caused by inadequate protein synthesis due to liver disease.
- Oedema caused by inadequate protein intake
- Oedema seen in excessive protein losses due to kidney disease or wounds.
- 8. As conjugated proteins
- Example: Glycoproteins
What is the amino acid pool?
When proteins break down, they free up amino acids to join the general circulation.
These amino acids + diet derived amino acids = amino acid pool
What is protein turnover?
within each cell proteins are continually being made and broken down = protein turnover
Give examples of endogenous sources of protein.
Desquamated mucosal cells (generate about 50g protein per day)
Digestive enzymes and glycoproteins (generate about 17g protein per day)
If an essential amino acid is missing, how can the body obtain it?
It can break down some of it's own protein.
If a particular nonessential amino acid is not available the body can make it from another. This process is known as________________?
Transamination is dependent on which vitamin?
Explain why energy deprivation can cause lean tissue wasting.
when glucose and fatty acids are limited, cells are forced to use amino acids for energy and glucose.
The body does not store proteins as it does carbohydrates (glucose as glycogen) and fats (triglycerides in adipose tissue).
The protein in the body is available as tissue components. When the need arises, the body dismantles it's tissue proteins and uses them for energy.
Amino acids can be stripped of their nitrogen and used for energy (either immediately or stored as fat for later use). This process is know as____________.
After Deamination, the remaining carbon fragments of amino acids may be used to produce what?
- Glucose (glucogenic amino acids)
- Ketones (ketogenic amino acids)
When amino acids are broken down, they are stripped of their nitrogen-congaing amino group which is converted to ____________, which is then released into the blood stream.
The liver converts toxic ammonia into a less toxic compound _______ and returns it to the blood stream.
In addition to protein synthesis, individual amino acids also......?
- Contribute to the synthesis of hormones and neurotransmitters.
- Detoxify thousands of chemicals
Supply antioxidant protection
Build bile acids
What are the physiological roles of Glutamine?
Most abundant AA in whole blood
Preferred fuel for enterocytes, lymphocytes and macrophages.
Combined with alanine for nitrogen transport in the blood
Regulation of acid base balance as precursor for urinary ammonia
Substrate for citrulline and arginine synthesis in the gut
Precursor of nucleic acids, amino sugars, proteins.
Conditionally essential - stress states: injury, sepsis, inflammation.
Is a precursor to the synthesis of Glutamate
Is involved in a glutamine-glutamate-GABA neurotransmitter function in the brain.
What role does Glutamine play in intestinal repair?
Stimulates intestinal mucosal growth and protects from mucosal atrophy.
- Prevents intestinal mucosal damage
- Decreases bacterial component leakage across the intestinal wall.
Mechanism of action = strengthening epithelial tight junctions!!
High levels of ________ appear to deplete glutamine stores.
The ability of lymphocytes to proliferate and generate killer cell activity has been found to be dependent on which amino acid?
How does Glutamine play a role in receiving the side effects of chemotherapy and radiation?
Chemo and radiation and injure rapidly dividing intestinal cells.
- Glutamine can:
- reduce degeneration of intestinal mucosa prevent intestinal mucosal injury
- protect liver function (through enhanced glutathione biosynthesis)
- increase immune function
- reduce permeability of the gut
Glutamine can help with intestinal permeability often accompanying which conditions?
- Coeliac disease
- Alcohol overuse
- adult and child asthma
- NSAID treated patients (e.g. in arthritis)
Glutamine can be used to support patients with HIV. What role does it play?
Reversal of malabsorption and protection of the small intestine.
Glutamine deficiency is a probable factor in HIV associated wasting.
(some studies suggest improvements in HIV positive patients dosed at 8g a day with regards to intestinal permeability and intestinal absorption)
Whats the recommended dosage of glutamine in trauma cases?
What is the supplemental dosage of glutamine for peptic ulcers?
Drinking 1 litre per day of cabbage juice in divided doses.
1.6g/day of glutamine for a month
What is the supplemental dosage of glutamine for HIV patients?
30 to 40g per day to prevent medication associated diarrhoea and to improve intestinal permeability.
Glutamate is a substrate for_________ synthesis.
Glutamate is a precursor for ________ synthesis.
Glutathione is a tripeptide consisting of which 3 amino acids?
Glutathione has a sulphur element (because of cysteine) - detoxes and neutralises substances such as______?
Glutamic acid (Glutamate) is not generally used in clinical interventions. Why is this?
Because of its neurotoxic effects
Which are the 3 amino acids essential for the functioning of the Urea Cycle?
A O C
Impairments of the livers Urea Cycle can lead to Hyperammonaemia. Symptoms of this include...
- Chronic fatigue
- Nausea and diarrhoea
- Lack of concentration
- Mental confusion
- Intolerance of high protein foods
Arginine is the precursor of____________
Nitric Oxide (NO)
What is Nitric Oxide synthesis blocked by?
High fat meals
High blood homocysteine levels
low antioxidant status
Lack of exercise
Give some clinical applications of Arginine
Coronary artery disease
Accelerate wound healing - collagen synthesis
Normal sperm count and motility; improves erectile function
The only proven clinical application of supplemental Arginine has been for which disease?
What is the supplemental dosage of Arginine for heart disease?
5.6g to 12.6 per day
Which two amino acids compete with Arginine for intestinal transport?
Oral supplementation of L-arginine can cause what symptoms?
- Abdominal pain
- Exacerbation of airway inflammation in asthma
- exacerbation od herpes infections
Name 3 drugs that Arginine can interact with.
What is the abbreviation BCAA?
Branched Chain Amino Acid
What are the physiological roles of Branched Chain Amino Acids?
BCAAs make up 35% of muscle protein and 50% of AA in dietary proteins
Directly stimulate protein synthesis, fully oxidised in mitochondria for energy, within the liver can act as precursors for lipids or ketone bodies
Name the 3 Branched Chain Amino Acids
V L I
Clinical Applications for BCAAs
Inhibit muscle proteolysis which can have a positive muscle sparing effect during exercise.
Oral administration appears to inhibit muscle glycogen degradation during exercise
Supplementation also attenuates N loss and protein wasting during bed rest.
A clinical application of BCAAs may be used for Anorexia. Explain the mechanism.
BCAA compete tryptophan, phenylananine and tyrosine for uptake across the blood brain barrier as they share a transport mechanism.
- Research suggests high levels of serotonin are responsible for cancer anorexia.
- By decreasing the synthesis of serotonin - BCAA might increase appetite.
Where are BCAAs mostly found in the diet?
- Concentrated in the germs of grains
- Dairy products
What is the supplemental dose of BCAAs for malnourished elderly patients to improve appetite?
12g daily in capsules
BCAAs can interact with what 3 drugs?
________ function should be monitored closely if high doses or long term use of BCAAs is used.
What are the two sulphur amino acids?
Which amino acid is required for the synthesis of acetylcholine, creatine and epinephrine?
Methionine can be converted into __________________, a major methyl donor in the body.
1. __________ is synthesised from Methionine; is a component of ___________, ____________ and ___________.
Name some Methionine rich foods.
Hyper-homo-cystein-aemia that is unresponsive to vitamin supplementation sometimes responds to dietary restriction of ___________.
Methionine might act synergistically with ________ to decrease the risk of colon cancer.
Rates of methylation are much higher in tumour tissue than in normal tissue and most tumours are dependant on exogenous, preformed _________ for growth.
Preliminary clinical evidence suggests restriction of dietary 1.___________ in cancer patients might 2._________ tumour growth and improve cancer treatment outcomes.
There is evidence a high dietary intake of 1.___________ with salt and nitrates might increase the risk of 2._____________.
2. Gastric cancer
Hyperhomocysteinaemia is associated with an increased risk for _________ _________.
Which amino acid may aggravate existing liver damage in patients with liver disease?
Which amino acid is a neurotransmitter - principal excitatory AA in the brain, involved in movement, cognition memory and sensation?
Which amino acid is used in the phase II liver detoxification pathway (Sulphation)?
The physiological roles of Cysteine are:
Most sulphur foods are in the form of protein-bound Cysteine.
High-sulphur foods include eggs and legumes (high cysteine foods)
Cysteine is the source of sulphate (-SO4), used in the phase ll liver detoxification pathway - sulphation (used for many drugs, steroids hormones etc)
Sulphation increases water solubility of many hydrophobic compounds in preparation for their excretion in urine.
What is the derivative of L-Cysteine used in supplementation?
N-acetyl cysteine (NAC)
Cysteine is made from __________ and ________ in the _______. Which vitamins are needed?
Vitamin B6, B12
Cysteine is a precursor of which potent antioxidant?
The antioxidant effects of _______________ may explain its ability to prevent adverse effects caused by toxic chemicals and drug reactions.
The 1.______________ and free radical properties of 2.______________, might make it useful in the treatment of pulmonary and cardiac disease.
2. N-acetyl cysteine
______________appears to reduce cellular production of pro inflammatory mediators.
_____________ can impair platelet aggregation.
In patients with HIV, ______________ can increase levels of Glutathione.
Note: Increased concentration of glutathione seems to reduce oxidative stress associated with HIV disease and to improve the number and activity of CD4 T- lymphocytes
Cysteine supplementation (relevant in nutrition therapy) seems to be effective in:
Bronchitis 200-600mg twice a day
Influenza 600mg twice a day
Hyperhomocysteinaemia 1.2g per day
Chronic obstructive pulmonary disease (COPD) 600mg per day
Orally, and particularly when used in high doses, N-acetyl cysteine can cause gastrointestinal adverse effects including:
- Abdominal pain
Cysteine drug interactions:
Nitroglycerine: concomitant administration of N-acetyl cysteine and intravenous nitroglycerin can cause severe hypotension and intolerable headaches.
May interfere with insulin function in diabetics
Which amino acid improves sperm count and motility?
Creatine is a small peptide made of which 3 amino acids?
How does creatine phosphate improve congestive heart failure?
By preventing oxidative damage and improving circulation.
Glycine is required for the synthesis of:
- Haem pigment in RBCs
- Bile acids
- Skin & connective tissue
How does Glycine assist in detoxification?
It binds to a toxic substance forming a less toxic substance that can be excreted from the body
amino acid conjugation!
Which amino acid is found uniquely in green tea?
Which amino acid helps to increase alpha brain waves producing a calming, mood-enhancing effect without drowsiness?
Which amino acid is a precursor to the thyroid hormones, adrenaline and noradrenaline?
Which amino acid is a precursor to the neurotransmitter dopamine?