Silkworm Gland Enzyme Identified as Alpha-Type DNA Polymerase

This 1978 study by de Turenne, published in Biochimie, is a basic enzymology paper about how cells copy DNA — it has nothing to do with skincare or wound healing. The researcher purified a DNA-building enzyme from the silk-producing glands of the Bombyx mori silkworm and studied its chemical properties in the lab.

The enzyme, a large protein weighing roughly 150,000 to 220,000 units, worked best at a mildly alkaline pH of about 8. It was blocked by high salt levels, by chemicals that react with sulfhydryl groups (a type of reactive chemical group on proteins), and by polyamines. It had no nuclease activity, meaning it did not cut DNA strands, and it needed magnesium as a helper metal to function.

Crucially, the enzyme could only copy synthetic polydeoxyribonucleotides — short, lab-made DNA building-block chains used as templates — when they were paired with a matching starter strand. It could copy DNA-based templates but not RNA-based ones. Based on these traits, the author concluded the enzyme closely resembles a class of DNA-copying enzymes called DNA polymerase alpha, found in vertebrate animals.

As a purified-enzyme study in an insect gland, the paper cannot say anything about how this enzyme, or DNA polymerases generally, might behave in skin or other human tissue.