What is the Difference Between Polypeptide and Protein?

The main difference between a polypeptide and a protein lies in their size, structure, and complexity. Here are the key differences:

1. Size: Polypeptides are shorter chains of amino acids, while proteins are longer chains of amino acids. Traditionally, peptides consist of between 2 and 50 amino acids, whereas proteins are made up of 50 or more amino acids.
2. Structure: Polypeptides are strings of covalently bonded amino acids that are not folded into any specific structure, whereas proteins are strings of covalently bonded amino acids that have folded into their correct shape. Proteins can adopt complex conformations known as secondary, tertiary, and quaternary structures.
3. Complexity: Proteins are generally more complex than polypeptides, as they can be comprised of one long chain of 100 or more amino acids or several amino acid chains joined together. Polypeptides are simpler in structure and can be referred to as oligopeptides, which are small chains of amino acids.

In summary, polypeptides are smaller, simpler, and less structured than proteins. Proteins are larger, more complex, and have well-defined structures, often playing crucial roles in various biological functions.

Comparative Table: Polypeptide vs Protein

The main difference between polypeptides and proteins lies in their size, structure, and composition. Here is a table summarizing the differences between polypeptides and proteins:

Polypeptides are simple structures composed of a variety of amino acids linked by peptide bonds, while proteins are complex polymer structures composed of many amino acids. Proteins are formed from one or more polypeptides joined together and can adopt complex conformations known as secondary, tertiary, and quaternary structures.