Reflecting back to proteins

hey guys, so I finally decided to settle down and review on amino acids and proteins , have been avoiding this topic for a while and I have absolutely no idea why :/ . So yes I am aware that it is really late, but hey better late than never right? Okay so let’s get started.

 

We all know the structure of an amino acid right? I really hope we do else that would be beyond sad. But before we get to the structure, what really is an amino acid ?

Amino acids are joined together by covalent bonds, they form  polymers that in turn make up the structure of a protein. I guess you can call them the building blocks that are used to make protein.

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Now even though I said building blocks don’t go thinking that you can go and build yourself a protein you know,

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Unfortunately that’s not how they work. Okay getting back to the structure each amino acid is made up of a carboxly group, amino group and a H connected to an R group , the R group is where each amino acid differs from one another.

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There are twenty amino acids that are found in the body, I am sure you are saying wow only twenty , well that is what I said when I first learned about amino acids. A little history for you, the first amino acid discovered was………

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ASPARAGINE in 1806 this amino acid was found in asparagus, so yep whoever came up with the name was really original.

Amino acids are divided into so many groups, there are nonpolar aliphatic R groups , polar uncharged R groups , aromatic R groups, positively charged R groups and negatively charged R groups.

The smallest amino acid that exists is Glycine , it is the smallest because it only has  a H attached to it.

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Another cool amino acid to check out would be proline, its really special because it forms a ring structure with its own amino group. :O

 

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As we said before proteins are made up of twenty amino acids, now something interesting is that there are twenty amino acids that the body needs to be healthy. Coincidence I think not! Out if this 20 about 10 of them are essential, now a lot of people get confused when they hear that only 10 of the twenty amino acids are essential, so I shall just clear this up for you. The truth is ALL the amino acids are essential we all need them to survive, but the term essential is also used to describe certain amino acids that the body cant synthesis  or produce on its own so it is received from the diet. Now if you are asking why they would use the word essential to describe this, I honestly don’t know, I have asked this question before, I mean there are so many words in the dictionary and they just had to choose the one that would confuse us! But hey that biochemistry for ya!

Examples of some essential amino acids would be

Arginine

Histidine

Isoleucine

Leucine

Lysine

 

And some examples of non- essential amino acids would be

Alanine

Asparagine 

Glutamine

Glycine

Serine

 

I do hope that I have cleared up that whole essential thing for you. Now we move on to Complete and Incomplete proteins.

Complete proteins would contain all 10 essential amino acids, the proteins that we get from animal sources would be complete proteins, also beans contain complete proteins.

Incomplete proteins lack one or more of the essential amino acid, most vegetables would be classed as incomplete proteins, beans however are an exception to this , because as we saw before they contained essential proteins.

 

Moving on ……moving on we have reached the testing for amino acids and proteins segement!!

For AMINO ACIDS we used the Ninhydrin reaction, when this reacts with the amino acid it forms a purple coloured imino derivative, this is very useful since most amino acids are colourless.

For PROTEINS we use the buiret test and we should all be familiar with this test by now. Buiret is a light blue solution containg Cu2+ ions, when mixed with the protein it also turns a purple colour as you can see it would be very easy to get mixed up with the ninhydrin reaction, but since all of you are so smart you know that is for amino acids only. The purple colour would appear when the buiret reagent reacts with the peptide bonds of the polypeptide chain to form a complex. 

 

Peptide bonds.

A peptide bond is a chemical, covalent bond that is formed between the amino group of one amino acid to the carboxyl group of another amino acid. It is these peptide bonds that link amino acids to form long chains. Peptide chains are written down with the free amino group on the left and the free carboxyl group on the right.

Don’t believe me have a look for yourself  😛

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Proteins

 There are different functional classes of proteins which are :

Receptors

Channels

Transport

Storage

Enzyme

Structural

Immune response

 

There are also different types of proteins such as

Globular proteins eg enzymes

They vary in secondary structure

Approximately spherical shape

Water soluble

Function in dynamic roles

 

Fibrous proteins

One dominating secondary structure

Typically narrow, rod like shape

Poor water solubility

Function in structural roles ( cytoskeleton, bone, skin)

 

Membrane proteins

Inserted into membranes

Poor water solubility

Function in cell communication

 

So we have reached the end of my first refection on proteins I do hope you enjoyed it, and that it was very informative to you! Thank you for reading and show your love by hitting the like button  :*

 

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