Recently, in the April 30, 1999 issue of the journal Science,
Drs. Culotta and O'Halloran reported that this second chaperone
protein directly supplies a molecule of copper to SOD and showed
how the chaperone is a necessary ingredient for the free
radical-destroying protein's activity. "No one thought SOD would
need a chaperone," said Dr. Culotta. A long-standing paradox,
she noted, was that although in a test tube SOD soaks up copper
molecules like a sponge, "[SOD] can't find copper inside a
living cell." She and her collaborators now recognize that this
is because the potentially dangerous metal is so well hidden,
bound up by several protective proteins. "Only vanishingly small
amounts of free metal are normally available in cells, and
elevated levels may only be present in disease," said Dr. Peter
Preusch, a biochemist at NIGMS. He described the new work as
being "of profound significance." According to Dr. O'Halloran,
the recent findings render the copper chaperone a "suspect in
the mystery of Lou Gehrig'