Sizes of Peptides, Amino Acids, Proteins…

Size of Amino Acids

The average molecular weight (based on the weight of a hydrogen atom being 1) of each amino acid is approximately between 100 and 125 Daltons.

Size of Peptides

The size of a peptide plays an important role in its ability to penetrate the skin. In general, peptides with a size of up to 500 Daltons (Da) can penetrate the upper layers of the skin, such as the epidermis.

However, for a peptide to penetrate into the deeper layers of the dermis or into the bloodstream, it must be sufficiently small and sufficiently lipophilic (i.e., soluble in fats).

  • Molecules with a size of up to 500 Daltons often penetrate the upper layer of the skin (the stratum corneum of the epidermis), but their penetration into the dermis is limited.
  • Peptides with a molecular weight greater than 1000 Daltons (for example, larger peptides or proteins) often do not penetrate deeply into the skin and remain in the upper layers of the epidermis, without reaching the dermis.

Thus, peptides with a size of up to 500 Da can penetrate the skin and exert effects, such as moisturizing, stimulating collagen synthesis, and other cosmetic or therapeutic actions. Peptides with a higher mass are more likely to remain on the surface or in the upper layers of the epidermis.

Sizes of Proteins

Proteins are polymeric molecules where amino acids serve as the monomers. Only 20 alpha-amino acids are found in the proteins of the human body. The same amino acids are present in proteins with different structures and functions. The individuality of protein molecules is determined by the sequence of amino acids in the protein.

Amino acids are organic acids containing one or more amino groups.

All α-amino acids, except aminoacetic acid (glycine), have an asymmetric α-carbon atom and exist as two enantiomers. Virtually all proteins are built from 20 α-amino acids, which, with the exception of glycine, belong to the L-series.