Abstract: This invention relates to a polypeptide which comprises the fragment SEQ ID No. 2 of peptide GSE24.2 (SEQ ID No. 1) and can reduce the production of free radicals and/or damage to the DNA structure of a cell, optionally comprising nuclear localisation sequences. The invention also relates to a polynucleotide and to a vector, which comprise sequences coding for said polypeptide, and to a pharmaceutical composition comprising said polypeptide, polynucleotide and/or vector. The invention further relates to the applications of the polypeptide such as the use thereof for treating and/or preventing diseases caused by an increase in oxidative stress and/or damage to cellular DNA, such as ataxia-telangiectasia or dyskeratosis congenita, or the use thereof in tissue engineering and cell culture for increasing the viability of same.