Tyr 324 acts as a nucleophile to form a covalent 3’-phosphotyrosine linkage to the DNA substrate.
Because the Heisenberg Hamiltonian presumes the electrons involved in the exchange coupling are localized in the context of the Heitler–London, or valence bond (VB), theory of chemical bonding, it is an adequate model for explaining the magnetic properties of electrically insulating narrow-band ionic and covalent non-molecular solids where this picture of the bonding is reasonable.
The molecules may form a supramolecular structure held together by non-covalent forces, such as Van der Waals force, π-π, and CH-π bonds.
This means that they use a metal ion to aid the transfer of an ester bond from the DNA phosphodiester backbone to a catalytic tyrosine side chain, resulting in a long-lived covalent phosphotyrosine intermediate that essentially unified the nicked DNA strand and the enzyme as one molecule.