4a. Biochemistry - Proteins, Enzymes Flashcards
What are the building blocks for proteins?
Amino acids
What four elements do amino acids contain?
Carbon
Hydrogen
Oxygen
Nitrogen
Which element distinguishes proteins from fats and carbs?
Nitrogen
How many different amino acids does the body need to create the proteins needed to function?
20
Which functional groups make up amino acids?
Carboxyl
Amino
Side chain of R that determines characteristics
What are the bonds that join amino acids together?
Peptide bonds
How do amino acids join together?
Dehydration synthesis
What are 2 amino acids joined together called?
Dipeptide
What are 3 amino acids joined together called?
Tripeptide
What type of peptide is aspartame?
Dipeptide
Neurotoxin
What type of peptide is glutathione?
Tripeptide
Antioxidant
Which three amino acids make up glutathione?
Cysteine
Glutamate
Glycine
Why do we need to ensure a good supply of cysteine in our diets?
We don’t have enough in the body which can impair glutathione production
Which foods are a good source of cysteine?
Legumes
Eggs
Sunflower seeds
What are the two types of amino acids?
Acidic side chains
Basic side chains
What do amino acids with acidic side chains do?
Release hydrogen ions
What do amino acids with basic side chains do?
Bind to hydrogen ions
What determines whether or not the amino acids release H+ or bind to hydrogen?
The pH of the surrounding fluid
What effect does the pH of the surrounding fluid do to a protein?
Effects its 3D structure and function
i.e. ceviche - raw fish - starts off soft, then goes hard when lemon juice squeezed on it
What characteristic do non-polar amino acids have?
Hydrophobic
How does a non-polar, hydrophobic amino acid react in a watery environment?
It folds to be on the inside of the protein structure, away from water
Example of a non-polar, amino acid
Tryptophan
What characteristic do polar amino acids have?
Hydrophilic
How does a polar, hydrophilic amino acid react in a watery environment?
It folds to be on the outside of the protein structure, interacting with the polar water molecules
Example of a polar, hydrophilic amino acid
Tyrosine
Examples of functions of proteins
Fluid balance in blood e.g. albumin Alternative energy source Clotting mechanisms e.g. clotting factors Enzyme production Storage molecule e.g. ferritin
What is the 3D structure of a protein key to?
Its function
What is the process whereby a protein’s structure changes?
Denaturing
How can proteins become denatured?
Heat - cooking (e.g. egg whites)
Heavy metals e.g. lead, mercury
What is needed to digest proteins?
Enzymes
How are proteins digested?
Mouth - mechanically broken down
Stomach - pepsin enzyme breaks down peptide bonds between the amino acids
What is pepsin?
Enzyme
Released by gastric cells
What is the inactive form of pepsin called?
Pepsinogen
What activates pepsinogen into pepsin?
HCl
What is required for pepsin to function properly?
Fluid pH of 2
Adequate stomach acid
What happens when protein-rich chyme enters the small intestine?
Hormone CCK is released
Triggers release of pancreatic enzymes
What are the pancreatic enzymes?
Trypsin
Chymotrypsin
What happens to proteins once the pancreatic enzymes are released?
Broken down further into tripeptides, dipeptides and single amino acids by pancreatic juices and brush border enzymes
Absorbed into blood
What are nucleic acids?
Largest molecules in the body
Used to store genetic information
What are the most common nucleic acids?
Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)
What are the building blocks of nucleic acids called?
Nucleotides
What do nucleotides consist of?
Phosphate group
Sugar
Nitrogenous base
What are the functions of nucleic acids?
DNA - template for protein synthesis
RNA - copies specific sub-sections of DNA (genes) and translates it into proteins
What do the nucleotides in DNA contain?
5-carbon sugar deoxyribose
DNA contains which four nucleotide bases?
Adenine
Cytosine
Guanine
Thymine
Which nucleotide bases are purines?
Adenine
Guanine
Which nucleotide base pairs with adenine?
Thymine
Which nucleotide base pairs with cytosine?
Guanine
What is the structure of DNA?
Two strands wound together like a twisted ladder
Double helix
What are the ‘sides of the DNA ladder’ formed from?
Sugar-phosphate bonds which are covalent bonds
What are the ‘rungs of the DNA ladder’ made from?
Hydrogen bonds
What is the structure of RNA?
Single strand of nucleotides containing ribose
When DNA is condensed down, what does it form?
Chromosomes
What are the ends of chromosomes called?
Telomeres
What affect does ageing have on telomeres?
Shortens them
What can accelerate the shortening of telomeres?
Stress Poor nutrition Poor sleep Lack of exercise Chemical agents
What is mutation?
A change in the DNA sequence
How can a mutation affect protein synthesis?
Can cause a change in the sequence of amino acids in the protein
This can cause the protein to be a slightly different shape
How may a shape change affect a protein?
May affect its functionality
How does a mutation cause sickle cell anaemia?
Mutation in gene that codes for the production of haemoglobin proteins
The haemoglobin becomes abnormally shaped and makes the RBCs defective
How does a mutation cause haemophilia?
Affects genes associated with clotting factors 8 and 9
Results in problems clotting
How can a mutation cause cancer?
Affects the genes that code for the proteins involved in regulating cell division
What is gene expression?
The process by which the instructions in our DNA are converted into a functional product, such as a protein
What can influence gene expression?
Environment the genes are bathed in
e.g. amount of toxins we’re exposed to
Certain nutrients
Which nutrients can influence gene expression?
Vit A Vit D EFAs Fibre Zinc
Can gene mutations affect enzyme activity?
Yes
What is MTHFR?
Enzyme necessary for converting folate (B9) into a form used for methlylation
What is the active form of folate called?
Methylfolate
What is methylfolate used for?
Metabolising homocysteine
associated with heart disease and dementia
How can people with MTHFR mutations be affected?
Higher homocysteine levels which could lead to heart disease and/or dementia
What may people with a MTHFR mutation benefit from?
Taking methylfolate
Avoiding excessive fortified folic foods e.g. cereals
What are enzymes?
Biological catalysts made from protein
What do enzymes do?
Create a lower energy way for starting materials to meet and react
Allows reactions to happen quicker in mild conditions within the body
Can enzymes be reused?
Yes, they don’t get damaged during a reaction process so can be used again
What are the molecules at the start of a reaction process called?
Substrates
What does an enzyme convert a substrate to?
A product
Example of enzyme, substrate, product
Enzyme - pepsin
Substrate - a protein e.g. food
Product - shorter protein chains
What happens when a substrate binds to an enzyme?
The enzyme stresses the bond in the substrate
Weakens it
Allows body to more easily break bond
What conditions do enzymes need to work correctly?
Correct temperate - 37C
Correct pH - could be acid or alkaline
Does an enzyme reaction need more or less energy than a reaction without an enzyme?
Less
What is the area on an enzyme where the substrate binds called?
Active site
What are enzyme co-factors?
Usually vitamins or minerals that are needed to activate an enzyme
Examples of enzyme co-factors
Zinc
Selenium
How is zinc an enzyme co-factor?
Required to activate the enzyme ‘alcohol dehydrogenase’ that breaks down alcohol
Why is selenium an enzyme co-factor?
Required for the antioxidant enzyme ‘glutathione peroxidase’
What can a lack of co-factor lead to?
A reduction in enzyme activity
What can affect the speed of enzyme reaction?
Substrate concentration
What is substrate concentration?
Enzymes work best when there is plenty of substrate
As the concentration of substrate increases, so does the rate of enzyme activity
However, a point will be reached when the enzymes become saturated and no more substrates can fit at any one time even though there is plenty of substrate available
The available substrate has to wait for enzymes to clear their active sites
(wait for a parking space to become available)
Example of substrate concentration in nutrition
The same enzyme converts O6 and O3
If someone ingests a lot of O6 and small amount of O3, the O6 will occupy the active sites meaning the O3 won’t be converted
What happens to molecules at high temperatures?
Move much faster
More collisions
Faster reaction time
How can high temperatures affect enzymes?
Atoms in enzymes vibrate too much
The weak bonds holding the 3D structure together can break
Enzyme becomes denatured
What effect does over-eating have on enzyme production?
Eating more means more enzymes are produced and used up
Eventually enzyme production can’t meet demand
Impairs digestion and the absorption of nutrients
Why is it important not to drink whilst eating?
Dilutes the digestive juices containing enzymes
Other than over-eating, what other factors can reduce digestive enzyme output?
Prolonged stress
Nutritional deficiencies
What treatment can be used to promote the production of digestive enzymes?
Herbal bitters
Bitter greens
Examples of enzymes in food
Bromelain - pineapples Papain - papaya Lipase - avocado Alliinase - garlic Actinidin - kiwi
How are plant enzymes different to human enzymes?
Tolerate a wider pH
Less likely to be denatured
What can denature plant enzymes?
Heat
Microwaving food
At what temperature do enzymes start to be destroyed?
Above 40C
What are the benefits of eating raw food?
More enzymes More vitamins More minerals More probiotics More antioxidants
What decreases the antioxidant value of food?
Cooking
Which compounds become more readily available during heating?
Lycopene - tomatoes
Beta carotene - sweet pots, carrots, mangoes
When is it advisable not to each raw foods?
SIBO - can cause immediate bloating
Thyroid disorders - raw turnips/cabbage (goitrogenic foods) can disrupt the uptake of iodine in thyroid gland
Yin conditions - lethargy, anaemia, feeling cold
Which enzymes are involved in the creation of inflammatory mediators?
Cyclooxygenase 1 and 2
Lipoxygenase 5
Which inflammatory mediator is created by cyclooxygenase 1 and 2?
Prostaglandins
Which inflammatory mediator is created by lipoxygenase 5?
Leukotrienes
Examples of natural anti-inflammatories
Turmeric
Ginger
Boswellia
Which drugs can inhibit enzymes?
Antibiotics
Statins
Which enzymes do antibiotics deactivate?
Zonulin - the enzyme necessary for the connections of amino acids in cell walls
Which enzyme does statins inhibit?
HMG-CoA reductase - used by liver to make cholesterol and CoQ10
What is systemic enzyme therapy?
Taking a large dose of proteolytic enzymes on an empty stomach so that some of the enzymes are able to reach the stomach intact
What are the functions of proteolytic enzymes?
Reduce inflammation
Efficient clearance of damaged tissue
Examples of proteolytic enzymes
Bromelain - pineapple
Serrapeptase
Pancreatic enzymes
What properties has bromelain shown to have?
Anti-inflammatory
Anti-cancer
Anti-clotting
Reduce plaques (atherosclerosis)
What properties does serrapeptase have?
Anti-inflammatory
How does serrapeptase help with reducing inflammation?
Thinning fluids formed from injury
Inhibits release of pain-mediating chemicals
Enhances CV health by breaking down fibrin - a by-product of blood coagulation
(dissolves blood clots/atherosclerotic plaques)
Reduces pain/swelling without inhibiting prostaglandins
How does serrapeptase alleviate pain?
By inhibiting release of bradykinin from inflamed tissues
Hydrolysing histamine
Which inflammatory mediator does serrapeptase not inhibit?
Prostaglandins
What are the therapeutic uses of serrapeptase?
Inflammatory mediated pain Scar tissue Endometriosis Autoimmunity Excess mucus
