Telomere
Repetitive DNA sequences (TTAGGG in humans) that cap the ends of chromosomes, protecting them from degradation and fusion, and shortening with each cell division.
Telomere length is widely studied as a biomarker of biological aging — shorter telomeres correlate with cellular senescence, and critically short telomeres trigger cells to stop dividing or undergo apoptosis. The enzyme telomerase can extend telomeres, but it is normally only active in stem cells and germline cells; most somatic cells lose telomere length with each division.
Epithalon (Epitalon) is one of the most studied peptides in the longevity space specifically because of preclinical evidence suggesting it can activate telomerase and elongate telomeres in human cell cultures. While the clinical significance of this effect in humans remains under investigation, telomere biology represents one of the more molecularly specific mechanisms through which a peptide has been proposed to influence the aging process.