Which enzyme is activated by the presence of more than one metal ion?

The proteinous part of an enzyme is known as:

All enzymes are chemically speaking:

Riboflavin and Renin are respectively .....

The systematic approach for naming enzymes has been recommended by the Commission on Enzymes of the:

The graph showing the concept of activation energy of an enzyme is given below. Observe the graph and choose the correct option for $M$ and $N$.