Which element is required by phosphofructokinase

Which element is required by
phosphofructokinase?
a) Magnesium
b) Inorganic phosphate
c) Manganese
d) Copper
Correct Answer - A
Phosphofructokinase (PFK) is —300 amino acids in length, and
structural studies of the bacterial enzyme have shown it comprises
two similar (alpha/beta) lobes: one involved in ATP binding and the
other housing both the substrate-binding site and the allosteric site
(a regulatory binding site distinct from the active site, but that affects
enzyme activity). The identical tetramer subunits adopt 2 different
conformations: in a ‘closed’ state, the bound magnesium ion bridges
the phosphoryl groups of the enzyme products (ADP and fructose-
1,6- bisphosphate); and in an ‘open’ state, the magnesium ion binds
only the ADP, as the 2 products are now further apart