Basic Building Blocks Of Protein

You might take heard the word proteins before, probably when learning about the food pyramid, only what are they made of? Where do they come from?

We get a lot of protein from our diets and nosotros need to make sure that nosotros consume enough as information technology helps strengthen our muscles. In fact, a person weighing ninety kg should consume roughly 70 grams of protein a 24-hour interval! Foods like meat, eggs and basics are all groovy sources of proteins only in fact all living things are made up of thousands of different proteins that all take specific jobs, such every bit adding structure to organs and tissues, or carrying molecules effectually the body.

Proteins are made up of long bondage of molecules called amino acids, named similar this because they are fabricated upwardly of amines and acids . These are often referred to equally the fundamental 'building blocks' of all proteins.

Reaction scheme showing the formation of amino acids from amine and acids

There are many different types of amino acrid (this one above is called glycine) and they can combine in many possible ways to form tons of different proteins. When two amino acids join together they class a peptide, named later on the bail that forms between them.

Reaction scheme showing the germination of a peptide from two amino acids

Proteins are made up of hundreds of thousands of these peptide-bonded amino acids in long chains! At that place are twenty possible amino acids in proteins, each with dissimilar side bondage that provide different properties. As a result, the order of each of these in the chain can actually result in big changes in the properties of the protein itself. The gild of the amino acids is determined by your Dna. Deoxyribonucleic acid stores genetic information, which basically ways it tells the body everything well-nigh itself, like center color, hair color or whether you take dimples or not. It also tells your trunk which proteins to make depending on what you need.

The sequence of amino acids in the chain is known as the primary structure.

Exercise ane:

Have a go at building some (very pocket-sized) proteins! Try and work out which amino acids form from each of these amines and acids. If you lot tin can, think about why the bonds are forming at the specific atoms you have chosen

ane.

Now encounter if you can combine these 3 amino acids to form a peptide!

Extension:

Remember the social club of amino acids in the chain is very of import for the backdrop of the protein. Endeavor and rearrange the order of amino acids to form a different peptide concatenation.

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In real life, proteins aren't just one really long straight chain. We also need to consider the secondary structure of a protein, which determines its shape. This is made upwardly by alpha helices and beta sheets.

The amino acids in the peptide concatenation tin rotate effectually their bonds making the protein very flexible. This allows the protein to fold in on itself. Hydrogen bonds can then form betwixt different segments of the concatenation, keeping these folds in identify. This is known every bit an alpha-helix equally it gives the protein a corkscrew shape. Hydrogen bonds grade between the acid group of ane amino acid, and the amine group of another.

In this diagram of the alpha helix, we see hydrogen bonds (in red) holding together different sections of the poly peptide chain, resulting in a screw shape.

Another thing we need to remember is that proteins don't exist as single chains, nosotros become lots of protein chains that tin can interact with each other. We refer to these every bit beta-sheets which form when hydrogen bonds form between two different poly peptide chains.

Beta sheet — Beta canvass with magnified area showing hydrogen bonds betwixt amino acids

In this diagram we encounter two protein chains stabilised past hydrogen bonds (in red), once again betwixt the amine of one amino acid and the acid of some other.

We besides demand to consider the interactions between different side chains on the amino acids in the protein. These tin can interact with each other causing the protein to fold even more than and requite it a 3D shape. These interactions are known as the third construction. If the interactions between chains are lost, due to a breaking of hydrogen bonds for example, nosotros see a loss in the shape of the protein. It is said to take been denatured. All the same, when the protein is denatured, the primary structure remains intact.

To learn more about protein structures (1°, ii°, 3°, 4°) run across the chemBAM page.

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Exercise two:

Have a piece of string. This represents the primary construction of a protein. Wrap it around your manus in a helix (corkscrew) shape. When you remove information technology from your hand y'all volition lose the shape of the protein.

However, if you add bag clips to the string, yous can keep the blastoff helix shape. These clips represent hydrogen bonds.

Now, with a partner, use more than clips to bring together your polymer chains together forming the beta sheet structure.

Finally, with different coloured clips showing the different potential intermolecular bonds from the amino acid side chains, attach many different parts of the proteins together to form the 3D shape- the tertiary structure.

At present, with your consummate structure, it is fourth dimension to denature the poly peptide. Undo all of the clips.

What happens to the primary, secondary and tertiary structure of a protein when it is denatured? What volition nosotros observe happening to the protein?

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The Experiment

A pdf version of this experiment is available hither. Please ensure you refer to the Condom card. Details for teachers or technicians tin can be found here.

AIM

To separate out the poly peptide from a spirulina tablet and test the effect of unlike additives on the protein construction.

You WILL NEED

one spirulina tablet
five examination tubes
150 mL of deionised water
funnel
filter paper
torch (a phone torch is fine)
Bunsen burner
tripod
ten drops 0.v M muriatic acid
washing upward liquid
thermometer
One egg
Glass beaker

Process

Role i – Spirulina

Crush a spirulina tablet into a fine pulverization and dissolve it in 150 mL of deionised h2o, stirring to help dissolution. This will take roughly 15 minutes

Filter to remove the undissolved chlorophyll until you become roughly 20 mL of the protein solution. Record whatever observations, e.thou. changes in colour.

Add approximately 2 cm of the poly peptide solution into each of 5 examination tubes.

Using a torch, polish a light on the poly peptide, recording the colour that y'all discover.

Go out one exam tube as a command.

In examination tube 2, add 2 drops of washing up liquid and shake. Note whatever colour changes. Shine the light on this solution, compare to test tube ane and note any changes in fluorescence.

In test tube 3, add together 5 drops of 0.1 M hydrochloric acid and shake. Note any colour changes. Shine the low-cal on this solution, compare to examination tube one and notation any changes in fluorescence.

At present add some other v drops of 0.i M muriatic acid and shake. Note any colour changes. Shine the calorie-free on this solution, compare to exam tube 1 and notation whatever changes in fluorescence.

Finally, place test tube 4 in a water bath placed on a tripod. Beginning heating the water bath, keeping an eye on the temperature and the solution. For every 10 ^oC, note your observations of the protein solution, and any changes in fluorescence.

Once y'all notice a significant change in colour/fluorescence, take this test tube out of the h2o and leave to cool back to room temperature. Note whatsoever colour changes. Shine the light on this solution and note any changes in fluorescence. How does this compare to the heated sample?

At (or above) the same temperature that yous removed test tube 4 from the water, heat test tube 5 for approximately 10 minutes. Notation any colour changes. Shine the light on this solution and note whatever changes in fluorescence. Leave this to absurd to room temperature and compare to exam tube 4.

Part 2 – Egg white

Note: this part of the experiment doesn't necessitate practical work and can just be discussed theoretically.

Crevice open up an egg and dissever out the egg white from the yolk.

Put the egg white into a drinking glass chalice above a Bunsen burner and estrus information technology.

Note any changes that occur and think most what is happening to the protein construction.

In one case yous see a permanent change, remove the egg white from the estrus and exit to absurd to room temperature, or on ice. Note any changes in the protein construction of the egg white.

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QUESTIONS

As well as the poly peptide, the spirulina tablets also comprise chlorophyll. Why doesn't this dissolve? What would happen if nosotros tried to deliquesce it in methanol?
When you smooth a torch on the poly peptide what colour is information technology? What colour must the protein be absorbing? For more information on fluorescence take a look at the sensing with fluorescence experiment
What happens to the fluorescence of the protein later heat/acid/soap?
What do the observations in question iii suggest has happened to the poly peptide? Think about your answer in terms of molecular interactions.
What happens to the heated protein in exam tubes 4 and five when they return to room temperature? What conclusions tin y'all draw from this?
What happens to the protein construction of the egg white when yous heat information technology? Does annihilation change when it is cooled? What tin can you determine from this?

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IN THE Research LAB

Researchers working with Dr Anna Peacock at the University of Birmingham employ proteins for many different purposes. In item, their piece of work involves designing peptide sequences capable of selective DNA recognition and binding, or as contrast agents in MRI.

Significant effort has been made into understanding how the protein matrix tin affect the properties of the metallic ion inside metalloproteins, with the ultimate goal beingness to generate bogus metalloproteins that are designed for specific purpose through tuning of the metallic ion properties. One major way this is happening is the simultaneous de novo (from scratch) pattern of miniature artificial poly peptide folds and metal ion bounden sites. These metal ion binding sites can organise the peptide structure for functions such equally enhanced binding to DNA.

Publications involving this research can be establish below:

De Novo Pattern of Ln(3) Coiled Coils for Imaging Applications

Incorporating metals intode novo proteins

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Files to download

pdf files:

Practice 1

Exercise 2

Experiment

Technicians guide

Prophylactic card

Teachers guide