Integrase, catalytic core, phage <p>Phage integrase proteins cleave DNA substrates by a series of staggered cuts, during which the protein becomes covalently linked to the DNA through a catalytic tyrosine residue at the carboxy end of the alignment [<cite idref="PUB00005224"/>, <cite idref="PUB00004261"/>].</p><p>The catalytic site residues in CRE recombinase (<db_xref db="SWISSPROT" dbkey="P06956"/>) are Arg-173, His-289, Arg-292 and Tyr-324.</p>