is a polypeptide a protein?

Answer 1

A polypeptide is a protein. Generally, it is at the first degree of protein with only amide bonds between amino acids.

There are 4 degrees of protein. I have just explained the first. The second degree would have alpha-helix, beta-sheet and/or random coil.

The third degree would see the protein to be in generally the 2nd degree with some amount of folding to form a 3-d shape.

The 4th degree is usually what layman calls it as protein is when 2 or more of the third degree coming in and they are bonded together to form a big chuck.

Answer 2

Only Taco girl's answer is correct: the rest are either pulling your leg, or just don't know.

A polypeptide is simply a chain of amino acids. In some cases it is sufficient to be a functioning protein with no further modification. The enzyme ribonuclease is an example: once formed it will spontaneously fold into the functional enzyme, so in this case the polypeptide and protein ARE the same. However, most polypeptides will need to be modified (adding sugar, phosphate, lipid etc), need be helped to fold by chaperones and then still need additional cofactors (like heme) or other polypeptides to join them before they become a functional protein

Answer 3

I think that most biochemists would not use the word "polypeptide" to describe a complete, functioning protein. Some proteins need multiple polypeptide chains to come together in a specific way in order to function. Other proteins are simpler - one polypeptide chain is enough to function, but we would probably call it a protein or an enzyme instead of a polypeptide.

So technically, I don't think there is a "yes" or "no" answer to this. If the polypeptide is functional on its own: yes. If not, no.

It turns out wikipedia backs me up on this, it says, "In order for a polypeptide to be a protein, it has to have some sort of biological function in the body."

I recently received my bachelor's degree in biochemistry, and have spent a lot of time studying proteins. I'm beginning work on my PhD in chemistry with a focus on biochemistry.

Answer 4

You have to be a certain molecular weight to be concindered a protein. Those who are two small are called polypeptide. They do not have the intricate 3 dimensional structure a protein would have.

Answer 5

polypeptides are generally considered smaller versions of proteins...they are large chains of amino acids

Answer 6

any protein is formed from peptides of amino acids
each peptide is composed from linked amino acids
so there is tri, di according to the number of peptides

Answer 7

YES!