The science

Twenty amino acids underpin almost every peptide in the human body. Here's what the chemistry actually looks like — and why the sequence matters so much.

Cyclic peptides fold back on themselves to form ring structures — and that single architectural trick changes almost everything about how they behave in the body.

Depot and sustained-release formulations solve one of peptide pharmacology's oldest puzzles: how do you keep a short-lived molecule working long enough to matter?

Disulfide bonds give peptides their three-dimensional shape and biological staying power. Here's the chemistry behind why they matter so much.

Peptides are fragile by design. Here's a plain-language breakdown of the enzymes that degrade them, where in the body it happens, and why it matters for pharmacokinetics.

Glycosylation changes how peptides behave in the body — stability, receptor binding, half-life. Here's the biochemistry, explained without the jargon fog.

Lyophilisation turns fragile peptides into stable powders. Here's the physical chemistry behind freeze-drying and what reconstitution actually does to a molecule.

Peptides are fascinating molecules — but the gut is ruthless. Here's why oral delivery remains one of pharmacy's hardest unsolved problems.

PEGylation attaches polyethylene glycol chains to peptides to extend their half-life. Here's the chemistry behind why it works — and its real limitations.

Peptide folding isn't just structural aesthetics — it determines receptor binding, metabolic stability, and why two near-identical sequences can behave completely differently in the body.

Peptide half-life determines how long a molecule stays active in the body. Here's the biochemistry behind why most peptides vanish so quickly — and what changes that.

Peptide mimetics are molecules engineered to replicate how peptides behave in the body — without the fragility. Here's the chemistry behind why that matters.

Peptide pharmacokinetics explains why these molecules behave so differently to small-molecule drugs — and why route of administration matters so much.

Receptor selectivity shapes everything about how a peptide behaves in the body. Here's what the chemistry actually tells us — and where the research still has gaps.

Peptide stability is more fragile than it looks. Here's what drives degradation — from peptide bonds to enzymatic cleavage — and why it matters in pharmacology.

Peptides and small-molecule drugs operate by completely different chemical rules. Here's what those differences mean for how each behaves in the body.

Amino acid sequence gives a peptide its identity. Three-dimensional shape gives it function. Here's how primary and secondary structure work — and why both matter.

Agonists activate receptors; antagonists block them. Here's how that simple distinction drives nearly every drug and peptide interaction in the body.

Recombinant peptide production turns microbial and mammalian cells into molecular factories. Here's how the science actually works, and why purity matters.

Peptides can't just be swallowed like a paracetamol. Here's why the route of delivery shapes everything a peptide does once it enters the body.

Solid-phase peptide synthesis made modern drug molecules possible. Here's how chemists build peptides one amino acid at a time — and why it matters.

A peptide bond is the single covalent link that turns individual amino acids into biology's most versatile molecules. Here's what the chemistry actually looks like.

Peptides are short chains of amino acids that act as chemical messengers across virtually every system in the body. Here's what the chemistry actually looks like.

Peptides rarely survive a trip through your gut. Here's the biochemistry behind why injection is so often the delivery method of choice.

Alanine is a non-essential, non-polar aliphatic alpha-amino acid that serves as one of the most abundant building blocks in proteins and plays a central role in glucose–alanine cycling and nitrogen transport in vertebrate metabolism.

Arginine is a conditionally essential amino acid with a positively charged guanidinium side chain, serving as a structural component of proteins and a direct precursor to nitric oxide via the urea cycle.

Cysteine is a sulfur-containing, conditionally essential amino acid whose thiol (–SH) side chain underpins disulfide bond formation, metal coordination, and redox-active catalysis across a wide range of proteins and peptides.

Glutamine is a conditionally essential amino acid — the most abundant free amino acid in human plasma — that carries a neutral amide side chain and serves as a key nitrogen shuttle in intermediary metabolism.

Glycine is the smallest and structurally simplest proteinogenic amino acid, characterised by a single hydrogen atom as its side chain and a central role in peptide backbone flexibility and nitrogen metabolism.

Histidine (His; single-letter code H) is a semi-essential, polar α-amino acid whose imidazole side chain carries a pKa near physiological pH, making it uniquely suited to proton-transfer reactions in enzyme active sites and protein structural chemistry.

Leucine is an essential branched-chain amino acid (BCAA) that the human body cannot synthesise de novo and must obtain from dietary or supplemental protein sources.

Lysine is an essential, positively charged α-amino acid that the human body cannot synthesise de novo and must obtain through dietary sources or supplementation; it serves as a structural and functional building block in proteins and peptides.

Methionine is a sulphur-containing essential amino acid that serves as the universal initiator of protein synthesis and as the principal methyl-group donor in one-carbon metabolism.

Proline (Pro; single-letter code P) is a cyclic, non-essential α-amino acid in which the side chain loops back to bond with the backbone nitrogen, making it the only proteinogenic amino acid with a secondary amine at its α-position.

Tryptophan is an essential aromatic amino acid that the human body cannot synthesise de novo, making dietary intake necessary for protein synthesis and for the production of several biologically significant metabolites.

Tyrosine is a conditionally essential aromatic amino acid that serves as a precursor to several physiologically significant molecules, including catecholamines and thyroid hormones, and is incorporated into peptide and protein structures via its phenolic side chain.