Covalent modifications of chromosomal proteins during aging

Covalent modifications of proteins introduce negative or positive charges into the molecules and thereby cause alterations in the ionic interactions of protein-protein or DNA-protein complexes. Whereas modifications of histones largely affect the organization of chromatin, those of non-histone proteins are believed to be involved in the expression of genes. These modifications during aging have been reviewed here. The available data suggest that the extent of covalent modifications of histones and non-histone chromosomal (NHC) proteins change during aging and such modifications may have an important role in the differential expression of genes at different phases of life span of an organism.