How does polypeptide differ than an equal protein?

Answer 1

Both peptides and proteins are made up of strings of the body's basic building blocks – amino acids – and held together by peptide bonds. In basic terms, the difference is that peptides are made up of smaller chains of amino acids than proteins. ... As a general rule, a peptide contains two or more amino acids.

Answer 2

Generally, polypeptides are shorter than proteins. It's a non-specific term, but usually it's amino acid < polypeptide < protein.

The "equal protein" is presumed to refer to a protein with the same amino acid sequence and length. In that case, there is another difference. Polypeptides aren't necessarily biologically active molecules. Once they're biologically active, they're proteins, or enzymes. All you care about in a polypeptide is the amino acid sequence. But in proteins, the primary structure is the amino acid sequence, but you're also very concerned about secondary structure (folding & conformational changes), tertiary structure (cross bonds among amino acids in the chain) and quarternary structure - association of multiple independent polypeptides into a single protein structure.

In short - with polypeptides all you really care about is the order of a long string of amino acids. With proteins, you're worried about exactly how that long string is bent, twisted, folded, and tied into other strings that have been bent, twisted and folded, to become a protein like hemoglobin that you need to breathe.

In summary - A polypeptide is a chain of amino acids. A protein is a chain of amino acids and thus a polypeptide. Short amino acid chains are called peptides. So the answer is if they are equal then they are the same thing, just different terms.

Answer 3

A polypeptide is a chain of amino acids, whereas a protein is a folded and functional form of a polypeptide. Proteins are composed of one or more polypeptide chains that have folded into specific structures to perform specific functions in the body.