Brookhaven Lab research eyes carcinogen

Brookhaven National Laboratory scientists have decoded the structure of an enzyme created by Stanford researchers that can turn a carcinogenic pollutant into a harmless compound.

The discovery could enable scientists to replicate the enzyme to remediate Hexavalent Chromium -- the carcinogen made famous by Erin Brockovich -- and it may one day also be used to target cancer cells.

Using the National Synchrotron Light Source facility at Brookhaven, structural biologist Subramaniam Eswaramoorthy was able to crystallize the enzyme and break it down to its simplest pieces.

Essentially, he found the components needed, or the recipe, that creates the enzyme that converts Hexavalent Chromium, also called Chromate VI, into a benign Chromate III.

Typically, an enzyme will force Chromate VI to become Chromate V and, through chemical reactions, turn it into VI again. "This toxic pollutant just bounces back and forth between the two forms," Eswaramoorthy said. "This is not a solution."

Often used as an ingredient in dyes and pigments, leather tanning, wood preservation and chrome plating of metals, Chromate VI can cause cancer in humans, according to the U.S. Environmental Protection Agency.

Knowing the structure of the enzyme that can break the compound down offers a way to protect water supplies and reduce contamination, said A.C. Matin, a professor in the Department of Microbiology and Immunology at Stanford University School of Medicine, where the enzyme was engineered in 2000.

"It has never been done before to figure out how . . . the conversion of Chromate takes place," Matin said. "We have taken the first big step."

The enzyme also can work with a "prodrug" cancer medicine to fine-tune treatment and enable targeted chemotherapy. "It can go everywhere, but it will be activated only in the cancer tissue," Matin said.

Stanford scientists plan to continue testing the efficiency of the enzyme for use in bioremediation -- to remove pollutants -- and cancer treatments while Brookhaven will analyze the atomic structures.

The findings were published last month in PLoS One, the online peer-reviewed journal from the Public Library of Science in San Francisco.