Collagen and Keratin

Well then, it’s been a while since I’ve been on this site. I don’t even remember what I have been doing half of the time *sigh*. Here is a little something about the basics of collagen and keratin. I get the feeling that I would be referring to it in the near future, not sure, but better prepared than not at all 🙂

Collagen

Collagen is a group of naturally occurring proteins, found in the bodies of animals. It is a triple helical structure, where two of its helical strands are fairly similar and the third has variation along random to specific points along its length, Like all other proteins is made up of a series of repeating amino acids but in the case of collagen, Proline, Glycine and its derivatives are in abundance.

In the human body, there are around 20 different types of collagen, they may be found in skin, hair and muscles, and thus it makes up about 25% of our body’s dry mass. As a matter of fact, collagen is in such abundance in our bodies that it is even the major constituent of cosmetic surgery.

So what makes collagen unique?

Arrangement of amino acids: Collagen contains some specific amino acids being Glycine, Proline, Hydroxyproline and arginine, with the amino acid subunit, glycine making up about a third of the entire structure. This would mean that Gylcine repeats itself about every three amino acid units in the structure. One should know that glycine is the smallest and simplest amino acid possible, seeing that its R group is simply a hydrogen atom. So basically it’s TINY!

Since glycine is so small it is required in that particular position. Why? Because the assembly of collagen’s triple structure puts this residue on the interior part of the structure, since it is the only residue which would fit in such a compact position. What about the others? It’s simply because the R groups are too large that they would therefore have to point outwards.

Tensile Strength: The bonds which hold the residues of collagen together are covalent bonds, which are very strong molecular bonds. This covalent bond relates to the primary structure i.e. if an individual strand was to be straightened out. Forming the secondary structure are hydrogen bonds between residues of the helix. Now a single hydrogen bond is not strong in any way, but when a large number of them come together a relatively strong additive force is caused.

Think of the strength like this. Ever broken a stick of macaroni? Simple right? Now try breaking five sticks at the same time. Still simple, but a little more effort is needed. Now try breaking an entire pack. It’s very difficult or maybe even impossible with average human strength. This is not the most accurate but a simple way to explain how hydrogen bonds work. Ant this high tensile strength is necessary. You have collagen in your bones and muscle tissue. Imagine if the collagen wasn’t this strong. Collagen is a major reason why bones are so strong, if it wasn’t for this quality your bones would be crushed under the sheer weight of your body, and thoracic and spinal organs/tissue would be under constant risk of injuries.

Types of Collagen

Keratin

Keratin is a fibrous structural protein found in animals and can be found in regions such as, hair, skin, nails, horns, hard part feathers etc.

Amino Acids and arrangement: Keratin’s arrangement is in the form of a poplypeptide chain (multiple amino acids linked together ) in the form of parallel sheets, the sheets which are held together by hydrogen bonds.
One of the amino acids present in keratin is Cystine, which makes up about ¼ of the entire structure. Cystine contains disulphide bonds, and it is these bonds which add to the stability of Keratin.

Tensile strength: Have u ever tried to burst a stand of hair? Ok, maybe when you have tried it simply slips between the small spaces in your hand. But assuming that it doesn’t trying to burst a strand of hair, takes a significant amount of effort , not exactly huge but, a little more than trying to burst thread.

Well Keratin AND Collagen is to blame for this. Earlier you have seen why collagen is so tough. Well the same basiacally applies to Keratin> Just remember that Keratin is NOT helical like collagen.

There is a video by Marshall Brain, where he takes a single strand of hair and sticks a number coins to it to see how much weight that single strand of hair can take before it finally snaps. (video refuses to upload so I’ll leave the link below)

I guess this is why Rapunzel’s hair makes her so…… I don’t know the word just look at it! It’s like, epic.