39aminoacid

39aminoacid is a label used in biochemistry to refer to a peptide composed of 39 amino acid residues. It does not denote a single, canonical sequence; rather it describes a length category that can encompass many different sequences. In teaching, research design, and some databases, 39aminoacid may appear as a shorthand for a short to mid-length peptide used to study general principles of protein chemistry.

Sequence variability is high for this length. Any combination of the 20 standard amino acids is possible, and in some contexts nonstandard residues or terminal modifications may be present. Because of this diversity, the exact mass and physical properties of a 39-amino-acid peptide can vary significantly. A rough mass estimate places such a peptide in the small protein range, typically around 3.5 to 4.5 kilodaltons, though modifications can shift this value. The peptide’s behavior—folding propensity, stability, and solubility—depends strongly on its specific sequence and any post-translational or chemical modifications.

Synthesis and structure: 39aminoacid peptides are commonly produced by solid-phase peptide synthesis or by recombinant expression, depending on the sequence and desired modifications. Structurally, they may adopt alpha-helices, beta-turns, or remain largely unstructured, with folding outcomes influenced by amino acid composition and termini.

Applications: Short peptides of this length serve as model systems to investigate folding, stability, protease resistance, and binding interactions. They are also used in teaching, vaccine design as epitopes, and as starting points in protein engineering studies.

See also: peptide, peptide length, short protein, protein engineering.