Educational guides and overviews on research peptides, what they are and how they're studied in the laboratory. For research use only.
Freeze-thaw damage is not one mechanism. It is interfacial denaturation, cryoconcentration and the pH shifts that follow it, cold denaturation, and adsorption to the tube wall. What the stability literature has actually measured for each, and where protein data is being extrapolated to peptides.
Read moreIsoelectric point tells you which direction to move the pH, not where the solubility minimum actually sits. A look at what the measurements say about net charge, hydrophobicity, co-solvents and the 83 mM of benzyl alcohol in bacteriostatic water.
Read moreA shelf-life date describes a system — material, container, temperature, humidity — not a molecule. Why lyophilized and reconstituted peptide behave as different materials, what Arrhenius reasoning buys you and where it fails, and which parts of storage practice are measured rather than convention.
Read moreThe preparative run decides which impurities leave the crude and which travel into the final material. How mass and volume load set the ceiling, why ion-pairing concentration re-orders a chromatogram rather than shifting it, and the arithmetic of a fraction-pooling cut.
Read moreOrthogonality is not a synonym for compatibility. Fmoc/tBu separates its two protecting-group classes by mechanism; Boc/Bzl separates them only by rate. That single distinction shapes which side reactions each scheme invites, from base-driven aspartimide to the carbocations strong acid leaves behind.
Read moreA stereochemically inverted residue produces a diastereomer with the identical molecular formula and the identical mass as the target. This guide covers the oxazolone and direct-enolization mechanisms that generate them, which residues and coupling conditions are worst, and how D-isomers are detected.
Read moreA certificate that invokes a reference standard is making a claim about a chain of transfers, not about a bottle. How values get assigned, how uncertainty accumulates, and what to ask of any document that says "compared against a standard."
Read moreTwo choices are locked in before the first coupling: the polymer the chain grows on, and the bridge that holds it there. Polystyrene against PEG-based supports, what swelling and loading actually control, and what Wang, Rink amide and 2-chlorotrityl linkers release when the peptide finally comes off.
Read moreSelank is tuftsin plus a Pro-Gly-Pro tail. This guide separates what has been measured — tritiated GABA binding in membrane preparations, IPSCs in rat hippocampal slices, serum peptidase inhibition at 20 μM, plasma degradation fragments — from what the literature never established, including any receptor of its own.
Read moreA research guide to semaglutide: the three engineered changes to the GLP-1 backbone, the class B receptor it binds, what cryo-EM and validated antibodies actually show, and why a purity percentage on a certificate does not establish that a vial contains this molecule.
Read moreSemax is a synthetic heptapeptide joining the ACTH(4-7) fragment to a C-terminal Pro-Gly-Pro extension. This guide covers its verified identity data, the nanomolar calcium-dependent binding site measured in rat forebrain membranes, the assay readouts it has been studied with, and the gaps left open.
Read moreSermorelin is the amidated N-terminal 29 residues of human GHRH. This guide covers its verified identity, the GHRHR cloning and cryo-EM work behind its mechanism, the alanine-scan and binding SAR, the specific cell and membrane systems it has been examined in, and the sizeable gaps that remain.
Read moreEvery peak on a peptide chromatogram other than the main one came from somewhere specific: a coupling that stalled, a base that closed a ring it should not have, a protecting group that stayed on. A walk through Fmoc and Boc chemistry, resin and linker choice, and the impurity classes each step leaves behind.
Read moreSS-31 (elamipretide) is a cationic aromatic tetrapeptide studied for its partitioning into cardiolipin-containing membranes. This guide covers verified identity data, the biophysical and proteomic evidence for its mechanism, the model systems it has actually been examined in, and what the literature does not establish.
Read moreTesamorelin is hGRF(1-44)NH2 with a single trans-3-hexenoyl group on Tyr1. This guide covers its verified identity, what the GHRH receptor literature actually establishes, the narrow set of systems the analog itself has been examined in, and the receptor-level data that has never been published.
Read moreA blend has no molecular identity, so this guide publishes no CAS or formula — and explains why. It separates what the literature establishes about the GHRH receptor and GHS-R1a from what has only been assumed about the pair, including a naming inconsistency that sends researchers to the wrong paper.
Read moreD-substitution, N-methylation, beta-peptides and peptoids each attack the peptide backbone in a different way. What each does to protease susceptibility and to conformation, what it costs, and which analytical methods can see it — including the two modifications that change no mass at all.
Read moreA purity percentage is the main peak's share of total integrated peak area on one chromatogram. This guide covers what that calculation assumes, why the same vial reports differently at 220 nm and 280 nm, how co-elution inflates the number, and what sits in the vial that the detector never sees.
Read moreA fatty tail changes almost everything about a peptide except its sequence. What albumin's fatty-acid pockets actually look like, whether acylated peptides demonstrably use them, where the acyl group goes and how it is protected on resin, what a spacer does — and why a lipid tail rewrites the analysis.
Read moreNAD+ is a dinucleotide, not a peptide, and it does two jobs that are usually discussed as one: a recycled hydride carrier, and a consumable substrate for sirtuins, PARPs, CD38 and SARM1. What has actually been measured, in which compartment, and why a flat whole-cell number can hide a collapsed mitochondrial pool.
Read morePEG is not one molecule but a distribution of a few hundred, and attaching it turns a defined peptide into a population. A walk through amine versus thiol conjugation, how site selection is actually steered, and why polydispersity defeats most of the analytical toolkit.
Read moreWhat DIC/Oxyma, HATU, HBTU and PyBOP actually activate, how they differ in racemization risk, why HBTU and HATU can guanidinylate a free amine, and which of those failures a routine chromatogram can and cannot see.
Read morePT-141 (bremelanotide) is a cyclic lactam analog of alpha-MSH. This guide covers its verified identity, the melanocortin receptor pharmacology its scaffold has been characterized in, the cell systems it has been examined in, and the limits of the record — including a subtype panel that exists in one laboratory.
Read moreA hydrocarbon staple is a ring-closing metathesis product installed on the resin, and its geometry is fixed by helix arithmetic. Where i,i+4 and i,i+7 come from, why olefin isomers survive purification, what a circular dichroism helicity percentage establishes, and where the literature disagrees.
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