Human Growth Hormone (HGH) is a
peptide hormone, specifically a 191-amino acid single-chain polypeptide.
I think it quite foolish to leave out of the conversation because it IS one of the best, most studied, and beneficial compounds ANYONE on here could ever happen to research, AND some high-quality products are available from sponsors here.
Key Differences:
- Size: Peptides are short, consisting of few amino acids. Proteins are large macromolecules, often featuring hundreds or thousands of amino acids.
- Structure: Peptides generally have simple, limited folding. Proteins possess complex 3D structures (secondary, tertiary, or quaternary).
- Definition Cut-off:
While arbitrary, a chain of 50 or more amino acids is usually considered a protein, while fewer than 50 is a peptide
.
Proteins and
peptides are fundamental components of cells that carry out important biological functions. Proteins give cells their shape, for example, and they respond to signals transmitted from the extracellular
environment. Certain types of peptides play key roles in regulating the activities of other molecules. Structurally, proteins and peptides are very similar, being made up of chains of
amino acids that are held together by
peptide bonds (also called amide bonds). So, what distinguishes a peptide from a
protein?
The basic distinguishing factors are size and structure. Peptides are smaller than proteins. Traditionally, peptides are defined as molecules that consist of between 2 and 50 amino acids, whereas proteins are made up of 50 or more amino acids.
In addition, peptides tend to be less well defined in structure than proteins, which can adopt complex conformations known as secondary, tertiary, and quaternary structures. Functional distinctions may also be made between peptides and proteins.
Related Topics:
protein peptide
Peptides, however, may be subdivided into oligopeptides, which have few amino acids (e.g., 2 to 20), and polypeptides, which have many amino acids. Proteins are formed from one or more polypeptides joined together. Hence, proteins essentially are very large peptides. In fact, some researchers use the term
peptide to refer specifically to oligopeptides, or otherwise relatively short amino acid chains, with the term
polypeptide being used to describe proteins, or chains of 50 or more amino acids.
