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Pap Pap Papain….

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This post is just to share a recent experiment I did but before we get to that lets just take a minute and look at this logo.

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To my knowledge this logo is misleading firstly the mixture they have is not 100% pure protein as the side of the box says it contains 15mg sodium in addition to 6g of proteins but I’m not here to argue that look at the back of the box.

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It says , “Indulge gelatine contains important proteins for healthier skin, hair and nails.”  This is misleading since we all know that gelatine is a hydrolysed form of the protein collagen and even though collagen does make up our skin and connective tissue we know that it is keratin that makes up our hair and nails and karetain and collagen are 2 completely different proteins.

  1. Collagen is made of 3 peptide chains which are left handed helix. These 3 helices are then coiled into a right handed coil (triple helix) forming the collagen structure. The peptide chains are predominantly made of glycine and proline and they both serve special roles within the molecule. Glycine works to stabilize since it is the smallest amino acid it fits on every third position of the chains which end up in the interior of the collogen structure or the center of the triple helix. Proline because of its cyclic structure aids in the formation of the coils in the triple helix structure of the collagen, since proline changes the direction of the chain due to is lack of maximum h bonds that can be formed.
  2. Keratin is a fibrous structural protein of hair, nails, horn, hoofs, wool, feathers, and of the epithelial cells in the outermost layers of the skin. The polypeptide chains of keratin are arranged in parallel sheets held together by hydrogen bonding.Of the amino acids in keratin, cystine may account for as much as 24 percent. The numerous disulfide bonds formed by cystine are responsible for the great stability of keratin: it is completely insoluble in hot or cold water and is not attacked by proteolytic enzymes (the enzymes that cleave protein molecules).

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Gelatine is made from collagen thus according to the research it is rich in Proline and glycine both of which are non essential amino acids meaning our body makes them we do not get them from our diet….. thus the box is misleading, Further more it says that the gelatine is important for hair and nails and since we know that keratin is responsible for hair and nails and keratin is mainly made of  cystine molecules the box is again wrong. (If it was made of cystine and keratin the following experiment would not have work as stated proteolytic enzymes such as papain doesn’t work in it)


GIFSoup
Now the video which i made based on the enzyme papain and how it works (its my first video so please feel free to give any tips)…..


Proteins

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Proteins
In the last post we established that proteins are made of a polypeptide chain/s and each protein is different due to the sequencing of the amino acids within the polypeptide chain. We also learned that in order to be called a protein the chain/s must have a molecular weight of over 5000g/mol. So let’s just get to it 😀
Importance of protein
Proteins are VERY important we are primarily made of proteins and they can be found in every aspect of our body, they can be used for :
Defence:

Antibodies are made of proteins and are used to protect our bodies from antigens by immobilizing them so they can be dealt with bywhite blood cells.Antibody

Movement:
Our muscles are made of proteins which can be easily contracted and relaxed which allows us to move.

GIFSoup

Enzymes:
Very importantly enzymes are proteins that regulate and catalyse chemical reactions within our bodies and are very specific and efficient some speed up reactions by almost 100% .

GIFSoup

Hormones:
Most hormones are made of proteins and act as messengers to help induce bodily activity example insulin for blood glucose concentration maintenance.


Structural support:
Fibrous proteins such as keratin and collagen act as support for connective tissues in ligaments as well as in structure such as hairs, feathers, quills etc.
The hard exoskeleton of insects is made of a glycoprotein called chitin.

americanCockroachAdult


Storage:
Such as the “yolk” of eggs which is made of the protein Ovalbumin which acts as a food store for that developing foetus.

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Transport Proteins:
That help transport molecules around the body the most famous being haemoglobin and mayoglobin. As well as Cytochromes that act as a carrier protein in the electron transport chain.


GIFSoup

In other words Proteins are very important and can be found everywhere!!


Levels of Protein Structure:
Proteins can generally have 4 structures:
1) Primary structure:
The actual sequence of the proteins along the chain eg.
[-Serine-Alanine- Leucine-Leucine-Tryrocine-]
Or [-S-A-L-L-Y-]

(see what I did there )

2) Secondary Structure:
This is where the interesting stuff happens; here folding starts to take place and the alpha helix or beta sheet are formed.

Alpha helix – a rod like shape, the primary structure coils and this folding occurs due to hydrogen bonds being formed between the carbonyl oxygen on the pepide bond and the Hydrogen on the amino group. Hydrogen bonds are formed nearly parallel and the side chains or R groups of each amino acid are on the outside of the spiral.
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NOTE: the alpha helix is mostly dominant due to the maximum use of hydrogen bonding since every peptide linkage (except those on the ends) takes place in H bonding. This enormous amount of bonding gives the helix structure stability.
Proline is not welcomed because it is cyclic and so one of its hydrogen is not available for bonding thus it forms and uneven number of bonds and the structure bends or leans in that direction.
Glycine is also not welcomed because it has a high “conformational flexibility” simply meaning it destabilizes the alpha helix and this is due to the fact that glycine’s R group is H.
Bulky or large R groups destabilise the alpha helix.

Beta pleated sheet- hydrogen bonds form between peptide bond on the same chain or different chain on a horizontal plane. There are parallel and anti parallel sheets.
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3)Tertiary Structure
Here it gets more interesting as all the different types of bonding start to take place as side chains interact. The protein folds in on its self and forms: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions.

Just so you understand how the bonding works:

Disulfide bonds

Oxidation of the sulfhydryl groups on cysteine. Different protein chains or are held together by the strong covalent disulfide bonds.

Hydrogen Bonding:

Where bonding occurs between two alcohols, an alcohol and an acid, two acids, or an alcohol and an amine or amide side groups.

Salt Bridges:
Salt bridges result from the neutralization o

f an acid and amine on side chains. Interaction is ionic between the positive ammonium group and the negative acid group. Any combination of the various acidic or amine amino acid side chains will have this effect.

Non-Polar Hydrophobic Interactions:
The hydrophobic interactions of non-polar side chains are believed to contribute significantly to the stabilizing of the tertiary structures in proteins. The non-polar groups mutually repel water and other polar groups and results in a net attraction of the non-polar groups for each other. This results in the non-polar side chains of amino acids being on the inside of a globular protein, while the outside of the proteins contains mainly polar groups.
(http://www.elmhurst.edu/~chm/vchembook/567tertprotein.html)

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4)Quaternary Structures

Here 2 or more polypeptide chains interact to form large structures one such is haemoglobin. However not all proteins consist of a quaternary structure.

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