Tissue from a brain tumor known as an oligodendroglioma. Genes from such… (Zachary Reitman, Duke Medicine )
Cancer researchers at Duke University Medical Center in Durham, N.C., have been studying the DNA in tumors called glioblastomas — hoping, ultimately, to help find a cure for the disease.
They haven’t found that yet, but they may have come across something else scientists are seeking: an enzyme that could help companies make nylon without depending on fossil fuels.
Duke researcher Zachary Reitman and colleagues reported Sunday in the journal Nature Chemical Biology that inserting glioblastoma genes into yeast allowed them to make an enzyme called 2-hydroxyadipate dehydrogenase — a molecule chemists need to make adipic acid, a key ingredient in nylon, from sugar.
Today, adipic acid, which is produced in vast quantities, is made using petroleum products.
Scientists would prefer to produce it by inserting genes into microbes that allow the organisms to turn sugars they consume into chemicals, explained Frances Arnold, a chemical engineer and biochemist at Caltech who was not involved in the Duke study.
Researchers had already figured out a way to use microbes to make adipic acid using 2-hydroxyadipate dehydrogenase, but the enzyme had proved hard to find. It was known, however, that human brain cancers made something similar to it. The Duke team tested a hypothesis that versions of genes associated with the glioblastomas could be used in yeast to make the chemical they sought. They found that they could.
“This is an example of how these things happen,” Arnold said.
But she stressed that the paper marked “an incremental advance” among many that would be required to make large amounts of adipic acid through green chemistry. Chemists will need to introduce many optimized genes into microbes to make the whole chain of enzymes needed to convert sugars into the chemical, she said.
“Each little brick in the building has to be shaped and honed and discovered. This is one of those bricks, but it’s not a building,” she said.
Companies already use microbial processes to produce chemicals like lactic acid and isobutanol, she said, but compared with adipic acid, those are simple to make. What’s more, industry would need to spend hundreds of millions to get production up to scale.
“It’s hard to compete with carbon, because it’s cheap,” Arnold said.
But she noted that adipic acid was a "big-scale chemical ... if we could make it from microbes rather than fossil fuels, that would be great."