Manganese Outperforms Magnesium in Mouse Embryo DNA-Building Enzyme

Birnie and Fox, writing in The Biochemical Journal in 1967, studied how an enzyme from mouse embryo tissue assembles polydeoxyribonucleotide, a DNA-like chain of nucleotide building blocks. This is basic enzymology, not a skin or medical study: the goal was to understand the chemistry of a DNA-building enzyme, not any therapeutic effect.

Working with cell-free extracts prepared from mouse embryos, the researchers tracked how the enzyme incorporated a radioactively labeled building block, tritium-tagged thymidine triphosphate, into new nucleotide chains. They found the enzyme, DNA nucleotidyltransferase (which adds nucleotide units onto a growing DNA strand), required all four matching DNA building blocks, a template strand to copy, and a metal ion to function, matching the behavior of similar enzymes already known from other mammalian tissues.

One feature stood out: unlike many other mammalian versions of this enzyme, the mouse embryo enzyme worked far faster and more completely with manganese ions than with magnesium ions. Both metals produced peak activity at pH 6.4, but at that pH manganese boosted the reaction six to eight times more than magnesium did.

The paper reports only enzyme behavior in a test-tube extract. It says nothing about living cells, whole animals, or any medical or cosmetic use.