Putative nucleotide binding sites of guinea pig liver transglutaminase

Three peptides corresponding to glycine-rich internal sequences of the guinea pig liver transglutaminase molecule were synthesized. These were peptide 1 (amino acid residues 520–544), peptide 2 (amino acid residues 345–367) and peptide 3 (amino acid residues 45–69). All of the synthetic peptide demonstrated significant binding ability for both ATP and GTP. Peptide 1 was the best protector or transglutaminase activity from both ATP and GTP inhibition, while peptides 2 and 3 protected the activity only from GTP inhibition. The data shown here lead us to propose putative binding site(s) for ATP and GTP guinea pig liver transglutaminase.