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