“Title about Protein”

 

So, last week we discussed Amino Acids… now, let’s be blunt, let’s be quick, let’s talk PROTEINS.

Protein Structure: There are four levels of protein structures and those are as follows
v  Primary

v  Secondary

v  Tertiary

v  Quaternary

But, what determines these levels of protein structure?
Who says polypeptide chains? Who says the linear sequence of amino acids? Who says both? Well I obviously don’t know who said what, but if you said both, you’re right!

Now let’s talk about how the levels are determined…

 

 

 

 

RECAP!!

As blogged before, the bond between two amino acids is called a peptide bond.

Peptide bonds are formed removing a water molecule from two different amino acids. The sequence of amino acids determines the positioning of the different R groups and this positioning determines the order in which the proteins fold and essentially the structure of the molecule.

PRIMARY STRUCTURE:

The linear sequence of amino acids that make up the polypeptide chain is determined by the genetic encoding of the sequence of nucleotide bases in the DNA.

 

SECONDARY STRUCTURE:

 

This is the regular folding of regions of the polypeptide chain. Two of the most common types of ‘protein folds’ are called the α – helix (coiled) and the β pleated sheet;  which is folded.

Compared to other conformations, the α-helix if formed more readily due to its optimal use of internal hydrogen bonding.

 

 

 

The Hydrogen bonding in the secondary structure occurs between atoms in the peptide bond

TERTIARY STRUCTURE:

Tertiary… this is a three dimensional structure and is formed by the twisting of the polypeptide chain. The linear sequence of amino acids is usually folded into a compact structure and becomes stable by many non-covalent interactions between the side groups of the amino acids.

 

QUARTERNARY STRUCTURE:

Not many proteins reach to this stage of folding (protein structure) but one example of a protein that has the structure is Haemoglobin. This structure is formed by the combination of more than one polypeptide chain. Interactions between them are; ionic, disulphide, hydrogen bonds and hydrophobic (not afraid of water, but rather ‘water hating’) interactions.

 

 

 

RANDOM FACTS ABOUT PROTEINS.

• About 18-20% of the body’s weight is protein.

 

• Hair is made up of a protein called keratin, which forms a helical shape. It contains sulphur bonds and so the more sulphur links present, the curlier a person’s hair can be. (I LOVE CURLS)

 

• Protein is a macronutrient; these provide calories/energy and are essential for survival.

 

• The lifespan of most proteins lasts two days or less.

 

• Without Albumin, the human body would begin to swell. (When I think of Albumin, I think of eggs.. when I think of eggs, I think of PROTEIN)

 

• Protein in semen acts on the female brain to prompt the ovulation process. #fertilize #dontgetideas #okaygetideas

 

• Errors in protein function can cause diseases such as Alzheimer’s and cancer.

 

•  The body needs protein to grow, heal, and carry about nearly every chemical reaction in the body.

 

• Complete or Whole Proteins contain all nine of the essential amino acids.

 

• Insufficient protein in diets can prohibit weight loss.

 

 

References:

Pictures

http://www.vitalityfitnesscalgary.com/protein-4-reasons/

http://www.slapcaption.com/josh-nichols-weight-loss-success/

http://hanguyenbiologyhlblog.blogspot.com/2013/01/proteins-homework.html

 

Information

http://www.bodybuildingpro.com/proteinrating.html

http://www.nature.com/horizon/proteinfolding/background/disease.html

http://www.youtube.com/watch?v=ZWLNkEJloJA&feature=youtu.be

 

 

 

AMINO ACIDS AND PROTEINS!

CALL ME ACID…… AMINO ACID *brings in intro music*

Amino!!!!!!! I think I’ll name my daughter that. Anyways, onto the topic of amino acids and proteins. Amino acids are the initial structures for one of the most important biological compounds out there i.e. PROTEINS. Proteins have many functions in the world we live in today that we know of and don’t know of. To generalise, some of these functions include receptors, channels, transport, enzymes, storage, structural and immune response. Let go a bit deeper into the biochemistry of the building blocks which make up proteins, i.e. amino acids.

 

ALL THAT R GIRL!!!!!!!!!!

Soooooooooo….. If I show you a Fischer diagram of a molecule, how would you know if it’s an amino acid or not. What’s that? You don’t know? Well I’m not shockedJ.  In my own words, an amino acid can be described as an α carbon bonded to four different groups. But not just any four groups. The four groups must be a hydrogen atom, a carboxylic group, an amino group and a R group.

 

 

Another question: So how can we distinguish between the different amino acids?

Answer: Via the R groups of course.

What makes each amino acid different is the R group. The R group can range from very small for example Glycine (smallest amino acid) to very large e.g.  Tryptophan (largest standard amino acid). The R groups can be split up into different categories.

1. Non polar, aliphatic R groups e.g. Glycine.
2. Polar, uncharged R groups e.g. Serine.
3. Aromatic R groups e.g. Tyrosine
4. Positively charged R groups e.g. Lysine
5. Negatively charged R groups e.g. Glutmate.

 

 

AMINO ACID ABBREVIATIONS

The names of some amino acids can be abbreviated for the purpose of ease. Here is a chart showing some names and abbreviations which can be a three letter code or a one letter code.

 

 

MARRIAGE OF CYSTEINE 

When two cysteine molecules react with each other, they go through an oxidation reaction where they lose hydrogen. A bond between the sulphurs in the molecules form. This bond is called a disulphide linkage and the new molecule is called cystine. A reduction reaction can take place in cystine where hydrogen is gained and the two cysteine molecules are reformed.

 

 

ZWIT ZWIT

Amino acids can exist in the non-ionic form and also the zwitterionic form. It is quite easy to explain how one changes to the other. A proton/hydrogen from the carboxylic group adds itself to the amino group to form the zwitterion. The carboxylic group will now have a negative charge and the amino group will take a positive charge.

 

 

DON’T GET IT TWISTED (Ninhydrin reaction vs Biuret’s test)

Did you know that amino acids are colourless? So how do we know they a part of a substance? We test for them….DUH!!!!!!!! But which test do we use? Ninhydrin or biuret? C’mon, are you for real bro? We use Ninhydrin which ONLY test for amino acids and not proteins. Biuret’s test works on proteins ONLY!!!!! In the ninhydrin test, if a purple colour is observed, then the test is positive for AMINO ACIDS. In the biuret’s test the same purple colour means that the test is positive for PROTEINS.

 

 

PEPTIDE BONDS!!!!!!!!!!

These are the bonds created between amino acids. When two amino acids react, the carboxylic group of one amino acid reacts with the amino group the other amino acid to form a covalent bond called a peptide bond. The two amino acids joined together are now called a dipeptide. The reaction is a condensation reaction meaning that water is given off.