Washington, June 12 (IANS): Copper plays a critical role in metabolism by helping move fat out of cells and into the blood stream for use as energy, a study said.

Findings about copper and fat cells, called adipocytes, by the group from the University of California, Berkeley, will be published in the journal Nature Chemical Biology in July, Xinhua news agency reported.

"Unlike other studies that link copper levels both to increased or decreased fat metabolism, our study shows definitively how it works -- it's a signal that turns on fat cells," said Christopher Chang, a professor of chemistry and molecular and cell biology at UC.

"If we could find a way to burn fat more efficiently, this could be a big contribution to dealing with obesity and diabetes."

Without enough copper, fat builds up in fat cells without being utilised.

Previously, Chang showed that copper is a key signalling molecule in the brain, tamping down over-excitation of nerve cells.

The new study shows that copper plays a role throughout the body and the signalling is not restricted to a few elements on the periodic table, like sodium, calcium and potassium.

"Copper is a brand new class; in a sense we have basically added a fourth letter to the alphabet, in terms of metal elements that contribute to the language of signalling," said Chang, who also is a faculty scientist at Lawrence Berkeley National Laboratory and a Howard Hughes Medical Institute investigator.

Chang's team found that an enzyme called phosphodiesterase 3 (PDE3) blocks cAMP, probably to prevent fat breakdown. Copper blocks this enzyme, thereby "putting a brake on a brake," he said.