Proteins and Amino acids Flashcards
(77 cards)
Describe the structural characteristics of proteins.
- Differentiated from carbohydrates and fats with the addition of nitrogen (as well as carbon hydrogen and oxygen)
- Amino acids are the basic building blocks of proteins BUT not all amino acids are protein building blocks. There are hundreds of non-protein amino acids that have other uses.
- Each amino acid contains
1. An amino group
2. A corboxylic group
3. A unique side group R which differentiates amino acids - Whilst there approximately 1000 amino acids in nature? The human body only uses 20?
- The amino acid chain is the primary structure and folds in a certain pattern to create 3-D structure which is closely linked to the function of the protein
Name the 9 essential amino acids
Clue: PVT TIM HiLL
Which of the essential amino acids is contentious and why?
Histidine
- it is synthesised in children but in adults whilst intestinal bacteria can produce histadine, it is not clear how much is provided.
- It is the only Amino acid that does not appear to impair protein synthesis when it is deficient in the diet so that seems to make it nonessential in nature.
List the main functions of protein
Growth and Maintenance
Hormones and receptors
Enzymes
Immunoglobulins (or antibodies)
Transport
Buffers
Fluid balance
Multiple functions of glycoproteins
How are proteins involved in the bodies growth and maintenance?
Proteins are the building blocks of muscles, blood, skin and most body structure.
- BONES are formed of collagen matrix (made up of amino acid) which provides a framework for minerals to deposit on.
- Ligaments, tendons, blood vessel walls, skin all use collagen as a building material
- ACTIN and MYOSIN filaments involved in muscle contractions are also protein
- Proteins are also needed for the replacement of cells. For example in the skin and the gastrointestinal tract cells are replaced every 4 to 5 days.
How are proteins involved with hormones and receptors?
Give 4 examples
Some hormones are derived from cholesterol such as reproductive hormones, cortisol, glucocorticoids for example.
Others are made from
Amino acids.
Tyrosine + Iodine»_space;> thyroid hormones
Tyrosine.»_space;> needed for the neurotransmitters dopamine, norepinephrine, epinephrine
Tryptophan»_space;> needed for the hormones/ neurotransmitters serotonin and melatonin
two polypeptide chains - insulin
one polypeptide chain - glucagon, PTH, calcitonin
Cell membrane proteins are receptors for hormones
How are proteins involved in the immune system?
Immunoglobulins are proteins found in blood and body fluids and are used by the immune system to identify and neutralise foreign materials such as bacterial viruses.
We have IgG, IgA, IgM and IgE
How is protein involved in transport systems in the body?
Give 4 examples
Some proteins act like a taxi service combining with other substances in the blood or within cells to provide a mode of transport. Without these proteins, we would not be able to deliver vital nutrients..
Eg:
Albumin - the most predominant protein in blood which can bind to calcium, zinc and B6 as well as steroids and fatty acids
Transferrins which bind to iron
ceruloplasmin which binds to copper
Haemoglobin which transports oxygen in the blood
How is protein involved in buffers?
Name 2 amino acids that buffer
This is to do with maintaining a pH of 7.35 to 7.45 in the blood. There are many mechanisms to help this and one of these are certain amino acids that have sidechain (R groups) that can easily pick up or let go of hydrogen ions thus helping to regulate acid balance in body fluids.
Proteins that have a lot of of these types of amino acids make good buffers.
Histadine is the best buffer .
Cysteine is also a buffer
What are some examples of glycoproteins?
Proteins bound to a sugar/carbohydrates,
Eg:
Mucins: found in mucus and saliva and provide protection and lubrication.
ABO blood type antigens - determines what blood group we are
Hormones: LH, FSH, T-SHIRT
Major Histocompatibility complex
proteoglycans shock absorbers that draw in fluid and keep it hydrated.
What is deamination in terms of protein metabolism?
Why does it happen?
Deamination is the removal of the nitrogen containing amino group from amino acids.
This is necessary for protein to be stored as fat or used as energy. When the protein drops nitrogen what’s left are amino acid fragments that can be used to produce glucose or ketones?
What is the byproduct of deamination and how are its potentially dangerous effects dealt with?
When the nitrogen group is removed from the amino acid, ammonia is formed which is very toxic.
It is the urea cycle that ensures it is excreted. Ammonia is converted to water soluble compounds so that it can be excreted as part of urine by the kidneys.
The Urea cycle takes place in the liver. if the liver is not functioning well it affects the urea cycle which can lead to a buildup of ammonia – hyper ammoniaemia.
Another benefit of the urea cycle is the that it is the sole endogenous source of amino acids arginine and citrulline, plus ornithine which is an important liver support and detox agent .
What is the importance of transamination?
It is very important in the synthesis of some non-essential amino acids .
When one non-essential amino acid is in good supply and another is low but in demand it is helped out by the one that is in good supply.
The amino group of an amino acid is transferred onto an enzyme. The enzyme then transfers the amino group onto a keto acid, thus forming a new amino acid.
It is a homeostatic mechanism
What is the co-factor transamination requires for a reaction to occur?
Where do we find it?
B6
Avocado
Bananas
Fish
green vegetables
lentils
Meat
pistachios
sunflower seeds
walnuts
Whole grains
What do we mean by the amino acid pool?
Why is it important to have a regular supply of protein?
- Amino acids freed from proteins when the proteins break down + amino acids from diet derived sources?
- Amino acid are utilised or excreted. They are not stored.
Essential amino acids generally have a longer half life than non-essential.
What might cause protein loss to occur?
- stress causes protein loss due catabolic actions of stress hormones such as cortisol and therefore when dealing with a stressed client they may need additional protein until the stress is dealt with
- Starvation or disease that leads to a lack of glucose and fat availability. The body will dismantle tissue proteins for energy and this will lead to tissue wasting.
What are the considerations when it comes to protein quality?
amino acid composition.
- Animal protein has all the amino acids
- Plant proteins are generally missing some and therefore in order to meet the needs for all essential amino acids you would need to combine plant sources.
digestibility
It’s all good and well to have all the amino acids but how well are they being absorbed?
- Animal protein is generally hard to digest
- Plant protein is easier to digest but
- it still has fibre which has to be got through in order to access the amino acid
- it also has anti-nutrient factors such as phytates and lectins
Quality is also determined by how the food is prepared - soaking, fermenting and sprouting improves digestibility.
Plants also contain fibre, probiotics and phytonutrients which they make make them a superior choice .
How might one optimise protein digestion?
- Chew properly so it is broken down as much as possible in the mouth.
- Eat mindfully so that the body is in a state of rest and digest.
- Consume zinc and B6 rich food which is vital for HCl production.
- Apple cider vinegar and a little water before meals.
- Better herbs 15 minutes before meals to stimulate the release of pancreatic juices.
- Betaine hydrochloride supplements to stimulate HCL
When is the fermentation of undigested protein that reaches the colon a problem?
Undigested protein which is in the colon is fermented. This can be used to produce short chain fatty acids, but it can also go down other pathways to create toxic metabolites such as ammonia to get into the bloodstream and create systemic problems.
This is more likely to happen with animal protein and when protein is combined with other foods or when too much protein is eaten.
What happens if an amino acid is missing but all the others are available to make a protein?
Which are the 4 amino acids most likely to be limiting.
The protein cannot be made.
If an essential amino acid is supplied less than the amount needed to support the protein synthesis it is called a limiting amino acid.
The amino acids in shortest supply and most likely to be limiting our lysine, threonine, methionine and tryptophan.
List six vegan foods that are complete protein
Buckwheat
Chia seeds
Hemp seeds
Pumpkin seeds
Quinoa
Tempeh
Do plant foods always need combining in one meal?
No.
The amino acid pool is stable enough to allows us to have access to amino acids throughout the day
What are the negative effects of animal proteins?
- More difficult to digest.
- Increases the acidic burden.
- The amino acid methionine is highly abundant in animal proteins and has an immune stimulating effect on T cells.
Excess methionine is associated with
- overactive immune responses – autoimmunity and chronic inflammation.
- increased homocysteine which is associated with atherosclerosis.
- And if not organic, can contain chemical residue.
- their food might contain pesticides
- oral or topical dosing of animals
What conditions/presentations are associated with long-term high intake of animal protein?
- Skeletal disease Osteoporosis: one of the ways that the body buffers the increased acidity from excessive protein, particularly animal protein is to release calcium – an alkalising mineral - from the bone
- Increased cancer risk - WHO classifies red meat as probable cause of cancer
-
Cardiovascular disease / atherosclerosis: increases oxidative stress and inflammation in the endothelium. This is problematic because when the lining is damaged, this is when arthrosclerosis becomes a risk due to the buildup of LDL ans
Foam cells
Disorders of liver function
Kidney disease - the extra acidity from high and more protein intake needs buffering by the kidneys. They are required to work hard to filter the increased urea that is generated.
Increased muscle soreness post exercise
Mitigate with alkaline rich fruit and vegetables to buffer the protein derived acid load