. "\"Any process that stops, prevents, or reduces the frequency, rate or extent of the covalent alteration of one or more amino acid residues within a protein.\" [GOC:mah, GOC:tb]" . . "negative regulation of protein modification process" . "down regulation of protein modification" . "down-regulation of protein modification" . "downregulation of protein modification" . . . "inhibition of protein modification" . . . . . . . . . . . . . . .