Glutathione is a tripeptide with one unusual bond that lets it survive inside the cell. The gamma linkage, the GSH/GSSG couple, and why the ratio is the only number that matters.
Peptides degrade through a small number of specific reactions — deamidation, oxidation, hydrolysis, disulfide scrambling, aggregation and adsorption. How to tell which apply to your sequence.
GHK-Cu is a coordination complex, not a peptide with copper added. What that means for buffers, chelators, pH, the blue colour as a sanity check, and how to read the literature.
Kisspeptin was found as a tumour metastasis suppressor and only later identified as the upstream regulator of GnRH release. Origins, nomenclature, KISS1R pharmacology and why kisspeptin-10 works.
Thymosin beta-4 is a 43-residue actin-sequestering protein. TB-500, as characterised analytically, is a seven-residue fragment of it. What that difference means for research.
Melanotan I, Melanotan II and PT-141 are all alpha-MSH analogues, but they engage the five melanocortin receptors very differently. A structural and mechanistic comparison.
Semax and Selank share a stabilising Pro-Gly-Pro tail and a country of origin, but they are built from unrelated parent molecules and studied in different literatures. A mechanistic comparison.