The peptide bond

A peptide bond forms when the carboxyl group (–COOH) of one amino acid reacts with the amino group (–NH₂) of the next, releasing water. The –CO–NH– linkage is rigid and planar due to partial double-bond character — giving peptide chains their secondary structures (alpha helices, beta sheets).

What is a peptide?

A peptide is a short chain of amino acids (2–50) linked by peptide bonds. Peptides occur naturally as hormones, signalling molecules, and antimicrobial agents. Synthetic research peptides mimic or enhance natural peptide biology for laboratory investigation.

What is the difference between a peptide and a protein?

Size. Peptides: 2–50 amino acids. Proteins: 50+ amino acids. Both are amino acid chains joined by peptide bonds. The key practical difference: peptides are typically synthesised by SPPS for research; proteins are usually produced by recombinant expression.

What is a peptide bond?

A peptide bond is the covalent –CO–NH– linkage between two amino acids. It forms by condensation (releasing water) between the carboxyl group of one amino acid and the amino group of the next.

Are peptides the same as steroids?

No — completely different compound classes. Peptides are amino acid chains binding cell surface receptors (GPCRs). Steroids (testosterone, Dianabol) are cholesterol-derived molecules binding nuclear receptors (AR, ER). Different chemistry, different receptors, different mechanisms.

How are research peptides made?

By solid phase peptide synthesis (SPPS) — building amino acid chains one residue at a time on an insoluble resin, then purifying to ≥99% HPLC purity. QSC uses Fmoc SPPS in Qingdao with independent Janoshik COA on every batch.

Are peptides safe for research?

Research peptides at ≥99% HPLC purity from verified suppliers (Janoshik COA) are appropriate for laboratory research. QSC compounds are sold strictly for research purposes only — not for human administration.