Characterization of the copper-containing amine oxidase from Trifolium pratense seedlings

We studied the kinetic characterizations of the Trifolium pratense seedlings copper-containing amine oxidase(TPAO) by using various amine-containing substrates.The catalyzing rate for all of amine-containing substrates can be ordered as diamines > polyamines > aromatic monoamines,and it shows an apparent trend in each category of substrates such as the longer the carbon chain,the lower the Vmaxis,so does the Vmax/Kmvalues but is opposite for the Kmvalue of TPAO.The distinct differences between the kinetic parameters for different amine-containing substrates indicated that the rate-determining step of the catalytic reaction strongly depends on the substrate’s chemical structure.It is concluded that both pH and ionic strength can affect the catalytic activity of TPAO via influencing the coulomb interaction-mediated enzyme-substrate docking processes,which can be attributed to the potential of charged groups from both substrates and the activity sites of TPAO by the regulation of ionic strength.