Proteins!!

[Scooby]

Does the tertiary structure consist of one polypeptide chain with many secondary structures, or of one polypeptide chain with only one secondary structure that has just folded further?

If the tertiary structure is made up of more than one secondary structure, do these all have to be the same type of secondary structure, or can there be a mixture of alpha helices and beta-pleated sheets?

Thanks!

[amilss]

There can be a mixture of alpha-helixes and beta-sheets. That's why there are so many different proteins which exist

[Scooby]

Cool. Thanks!

Another thing - can proteins contain phosphorus?

[Russ]

Proteins can, amino acids can't.

So the primary structure of a protein will never have any P in it, because it's not part of any amino acid side chains. However, it can be added to a protein later, for various reasons

[Scooby]

Alrighty. Thanks Russ!

[ggxoxo]

There can be a mixture of alpha-helixes and beta-sheets. That's why there are so many different proteins which exist

Don't forget random coils! So they can have alpha helices, beta sheets or just random coiling for secondary structure.

[jasoN-]

tertiary structure has one polypeptide chain
quaternary structure has greaterthan/equalto two polypeptide chain
quarternary can have a mixture, or it can have the one type (e.g. haemoglobin has only alpha helices)