Proteins and Amino Acids Flashcards
What percentage of body weight does protein account for?
17%
What are Amino Acids?
The building blocks of protein
Describe the structure of an amino acid
Contains-
An amino group-NH2
A carboxylic acid group-COOH
A unique R group which differentiates amino acids
What is another word for a protein
polypeptide
Describe the structure of a protein
The amino acid chain folds in a certain pattern to create its 3D structure. This structure is closely linked to the function of the protein (like a lock and key)
How many amino acids does the body use
20
How many amino acids are required for the synthesis of skeletal muscle
All 20
Which amino acids are required for the synthesis of glutathione?
cysteine, glutamic acid and glycine
Which 9 amino acids cannot be syntheised by humans/ are essential?
1.Phenylaline
2. Valine
3. Threonine
4. Tryptophan
5. Isoleucine
6. Methionine
7. Histidine
8. Leucine
9. Lysine
PVT TIM HiLL
What constitude a ‘complete protein’? Give a food source
One that contains all 9 essential amino acids. Animal sourced protein
Why is there a debate around whether histine is essential?
It can be produced by bacteria
What can cause denaturation of proteins
Heat exposure
PH variations
Alcohol
Heavy metals
Name the protein digesting enzyme in the stomach. At what PH is it optimally active?
Pepsin
PH2
Name 5 functions of proteins
- Structure of body tissues
- Movement (actin an myocin fibres in muscles)
- Carrier molecules (hemoglobin)
- Storage molecules (ferratin)
- Fluid balance (albumin)
- Enzymes
- Hormones
- Cell membranes
- Clotting
- Alternative energy source
Which amino acids can act as a buffer?
Histidine
Cysteine
Define damination, and explain it’s purpose
Removal of the nitrogen containing amino group
It is needed to be able to use protein as an energy source or to be stored as fat.
What toxic substance is formed during deamination?
Ammonia
How is it ammonia and excreted?
In the liver (urea cycle) it is converted into urea which is then excreted by the kidneys as urea in urine
What amino acids are formed in the urea cycle?
argenine
Citriline
ornithine
What can impairments in the liver’s urea cycle lead to?
Name 3 symptoms of this condition.
Hyperammonaemia
1 Chronic fatigue
2. Headache
3. Irritability
4. Poor concentration
5. Intolerance of high protein foods
What causes hyperammonaemia?
liver cirrhosis
Describe the process of transamination?
Why is it important?
Which nutrient is this process dependant on?
The amino group of an amino acid is transferred onto an enzyme. The enzyme then transfers the amino group on to a ketoacid to form a new amino acid.
It is needed for the synthesis of some non-essential amino acids. If a non-essentail amino acid is not available, the body can make it from another
B6
What is the amino acid pool derrived from?
The breakdown of proteins and diet derived amino acids
Are amino acids stored?
No, they are used or excreted. This is why it is essential to have a regular supply of protein in the diet.
How does the body obtain amino acids not provided by the amino acid pool?
It breaks down it’s own tissue
How does stress affect protein metabolism?
Stress hormones (e.g. cortisol) have a catabolic action.
What factors determine the quality of a protein?
Digestibility and amino acid content
What can you do to support the digestibility of a plant protein?
soaking, sprouting, fermenting
Name 3 ways to optimise protein digestion?
Chew thoroughly
No drinking with meals
Zinc and B6 rich foods (for stomach acid production)
Apple cider vinegar in water before meals
Bitter herbs before meals
Betaine hydrochloride supplements
Describe how the microbiome is involved in protein metabolism
Undigested protein that reaches the colon is fermented. This creates toxic metabolites that increase the inflammatory response and encourage the proliferation of opportunistic pathogens.
Why is it important to not overload the body with protein?
The fermantation products of protein are detrimental to health. They can induce systemic toxicity, nephrotoxiciy and carcinogenesis
What harmful substances are made when protein enters the colon undigested and ferments?
Ammonia, amines, sulphides, N-nitroso compounds
What is meant by the term ‘limiting amino acid’?
If an essential amino acid is supplied in less than the amount needed to support protein synthesis it is described as a limiting amino acid
Name the 3 limiting amino acids
Lyseine, threonine and methionine
What makes amino acids limiting?
They are found in the shortest supply in incomplete proteins
Name 3 vegan foods that are complete proteins
Quinoa
Buckwheat
Pumpkin seeds
Chia seeds
Hemp seeds
Tempeh
What is the limiting amino acid in beans?
In which other plant foods can you find this amino acid?
Methionine
Grains, nuts and seeds
What are the limiting amino acids in Grains?
Which other plant foods contain these?
Lyseine, threonine
Legumes
What is the limiting amino acid in nuts and seeds?
Which other plant foods contain this?
Lysine
Legumes
What is the limiting amino acid in vegetables?
Which other plant foods contain this?
Methionine
Grains, nuts and seeds
What are the limiting amino acids in corn?
Which plant food has this?
Tryptophan
Legumes
What are two negative effects of animal protein
- High levels of methionine which stuimulates T cells, in excess this can cause auto-immunity and chronic inflammation. Excess methionine also raises homocystein which is associated with atherosclerosis.
- Can contain hormones and chemical residues from pesticides. Quality is important here.
Name 3 adverse effects associated with high long-term protein intake in humans
Osteoporosis
Kidney disease
Increased cancer risk
Disorders of liver function
Atherosclerosis
What % of calories is generally considered ‘high protein?
20%
Explain the link between high-protein diets and osteoporosis
The acidic burden of animal protein can draw calcium out of bones to act as a buffer
Protein is also needed for the collagen within bones
How does high protein affect the kidneys?
Extra acidity needs buffering. They also need to filter the excess urea
Why is a high protein diet implicated in poor CV health
It is associated with oxidation and inflammation in the endothelium
Name 3 reasons why plant protein may be preferable to animal protein
- High levels of methionine and branch chain amino acids found in meat can be detrimental to health
- Plant proteins also contain fibre, phytonutrients and prebiotics
- Plant proteins assist healthy ageing because they have low levels of Leucine which can increase the expression of the enzyme TOR (an ezyme that regulates cell growth)
How much protein is reccommended (per KG of bodyweight for..
a. average person
b. athletes
c. pregnancy
d. lactation
e. Vegans and egg and dairy free vegetarians
a. 0.75g
b. 1.0g-1.6g
c. 0.75g + 6g
d. 0.75 +11g (post 6 months +8g)
e. 1 g (to accommodate for lower protein bio availability)
In the Western world, which population groups are most likely to be protein deficient?
Children-diet rich in ultra processed foods
Teenagers
Teenagers (as above)
Older people-immobility, poor chewing, lack of digestive enzymes and stomach acid
Anorexia nervosa
Recovering patients (protein needed for repair)
Homeless and disadvantaged
Drug and alcohol addicts
People with chronic digestive conditions and PPIs (low stomach acid impair digestion)
Chronic or active infections (deplete body proteins)
Apart from protein sythesis, name 3 other functions of amino acids
- Sythesis of hormones and neurotransmitters
- Are neurotransmitters (glycine)
- Methyl donors (methionine)
- Build bile acids (glycine and taurine)
- Precursors for nitric oxide production ( Arginine)
- Detox (phase 2 liver pathways)
- Precurors of endogenous antioxidants-glutathione
What can higher levels of leucine, isoleucine and homocysteine indicate?
CV disease
The amino acid Tyrosine is needed for the formation of two hormones. Name 2 of these.
Thyroid hormome and dopamine
Name the most abundant amino acid in the body
Glutamine
Name 2 functions of glutamine
1.It is the preferred fuel for rapidly dividing cells e.g enterocytes - gut health
Lymphocytes and macrophages- Immune health]
2. It behaves as a buffer (receiving excess ammonia) before releasing it to form other amino acids such as arginine and nucleic acids
Glutamine is the primary amino acid source for intestinal cells and helps to regulate tight junction integrity. Why is this important?
Intestinal permeability leads to the leakage of LPS into the blood which can lead to chronic diseases (e.g. autoimmunity)
As well as a glutamine deficiency name 3 other causes of leaky gut
- coeliac disease
- IBD,
- Cadidiasis
- alcohol
- SIBO
- Food allergies/ intollerances
- Nutrient deficiencies (zinc and glutamine)
- NSAIDs
- Chemotherapy
Name 3 ways to address intestinal permeability
- Glutamine supplementation
- Quercetin
- N-acetyl glutamine
- Zinc (for rapid cell division and gut junction support)
- Antioxidants
Herbs-tumeric, marshmallow, slippery Elm, goldenseal, Myrrh - Bone broth
Name 3 glutamine-rich foods
1.Cabbage juice
2. Spirulina
3. Asparagus
4. broccoli
5. Cod
6. Salmon
How does glutamine support immunity?
Supports lymphocyte and macrophage prolifereration and helps them to produce cytokines
How does glutamine support hypoglycaemia
Glutamine is a substrate for glyconeogeneis
How does glutamine support muscle recovery?
It is abundant in muscles and promotes faster exercise recovery
it reduces muscle breakdown
What co-factors are needed for the conversion of glutamate to GABA?
Vitamin B6
Zinc
Taurine
Why must we excercise caution when supplementing glutamine?
Cancer cells can use glutamine to fuel their growth.
Avoid in epilepsy and liver and kidney disease
What other amino acids form cysteine and which co-factors are needed for this to happen?
Methionine and serine
B6, B9 and B12
Name 3 direct food sources of Cysteine
legumes, sunflower seeds, eggs and chicken
Name 3 reasons why cysteine is so important
- It is a component of glutathione
- Needed for the formation of Co-enzyme A and taurine
- It is the rate-limiting amino acid for glutathione synthesis and is therefore crucial for detoxification
- Cysteine is the source of sulphate used in phase 2 liver detoxification pathway sulfation (used for many drugs and steroid hormones)
What is the supplement form of cysteine
N-Acetyl Cysteine
How can NAC support reproductive health?
Increases sperm concentration due to antioxidant properties
Increases testosterone
How can NAC support respiratory health?
Breaks up mucous by breaking the disulphide bonds in mucoportiens
How can NAC be used theraputically in diabetes mellitus and PCOS management?
Increases insulin sensitivity
Name 5 food sources of methionine
1.Meat
2. Brazil nuts
3. Sunflower seeds
4. Beans
4. Whole grains
What is the main function of methionine in the body?
Methionine is the major methyl donor. Needed for the homocysteine cycle and phase 2 liver detocification
What are the implications of raised homocysteine?
Damages the vascular endothelium and increases the risk of atherosclerosis and misscarriage
How can you lower homocysteine?
Use B6 and B12 to support methylation whilst restricting dietary methionine
Which 2 amino acids can sythesise carnitine and what co-factors are needed for this to happen?
methionine and lysine
Iron, Vit C, B3 and B6
Although rare, what could be a cause of carnitine deficiency?
Errors of metabolism SLC22A5 gene snip
Name 3 dietary sources of carnitine?
Nuts, seeds, avocado, asparagus, spinach, red meats, dairy
What condition can carnitine be used theraputically in?
Hyperthyroidism-it acts as a peripheral thyroid hormone antagonist.
What is carnatine’s role in ATP sythesis?
It assists ATP synthesis from fatty acids by facilitating the transportation of long-chain fatty acids across the mitochondrial membrane so that they could be oxidised to create ATP
In what way does carnitine act as an antioxidant?
It removes potentially toxic metabolites out of mitochondria.
How does carnitine help in ADHD?
It is shown to increase dopamine and acetylcholine production
Creatine is a peptide made up of which 3 amino acids
Argenine, glycine and methionine
Where is creatine mostly found in the body?
Muscles (95%)
Explain the main function of creatine
A fast source of ATP, it enables explosive power in the muscles (8-12 seconds). It enhances muscle activity (including cardiac muscle)
Name 3 functions of Glycine
- Collagen synthesis (collagen in 1/3 glycine)
- Liver detox- required to conjugate toxins in phase 2, and is a component of glutathione
- it is an inhibitory neurotransmitter in the CNS. Used to form acetylcholine
Which amino acid is converted to Taurine and what co-factor is needed for this?
Cysteine
B6
When might we need to supplement
During extreme illness, the body’s ability to make it is compromised.
Name 3 food sources of Taurine
Chicken/urkey thighs and fish
Why is Taurine added to baby formula
Babys have not learnt to sytheise it yet.`1
Where is theanine most commonly found?
Green tea
In what 3 ways does theanine exert a calming effect ?
- Crossed the blood/brain barrier and blocks glutamate (which is exitatory) and increase GABA (inhibitory) activity.
- It increases alpha-brain waves producing a calming mood-enhancing effect without the dowsiness
- Has been shown to increase serotonin and dopamine levels
Can you get enough theanine from drinking green tea?
No average tea drinker consumes 20 mg.
Theraputic dose is 50mg-200mg
What is Tyrosine derived from?
phenylalanine
Name 5 food sources of Tyrosine?
Nuts, seeds legumes, whole grains
Which hormones do Tyrosine help synthesise
Thyroid hormones
Dopamine
Epinephrine
Norepinephrine
Melanin
Name the main functions of Tryptophan
- Serotionin and melatonin synthesis
2 Used to make B3 which is needed for NAD and NADP for ATP production - Enhances the release of growth hormone
Name 5 food sources of tryptophan
- Brown rice
- Quinoa
- Pumpkin seeds
- Oats
- Banana
- Turkey
- Fish
8 Eggs
Why should you consume tryptophan supplements with a carbohydrate snack?
It is assisted across the blood/brain barrier by insulin.
Name 5 food sources of Phenylalanine
Avocado, brown rice, lentils, eggs, fish, meat soy
Which amino acid cab Phenylalanine be converted into?
Tyrosine
Which amino acid does Lysine compete for absorbtion with?
Arginine
Name 3 arginine and 3 Lysine sources
Arginine-Nuts, seeds, seaweed, meat
Lysine-Quinoa, legumes, tempeh, chicken, eggs, dairy, fish, red meats.
Which amino acid is a precursor to Nitric Oxide?
Arginine
Give 5 reasons why you might prescribe amino acids?
- To assist nuerotransmitter and hormone synthesis
- To restore gut barrier
- Blood glucose balance through better gluconeogeneis (glutamine)
- Utilisation of fatty acids for energy (carnitine)
- Detoxification (required for conjucation)
- Reduces oxidative damage (mantains glutathione)
What might impair the untilisation of amino acids?
Zinc, B6 and B12 deficiencies (needed for the interconvertions of amini acids.
