8 mil­lion

China Daily - - WORLD -

tons of plas­tic are dumped into the world’s oceans each year, ac­cord­ing to re­searchers.

“But they ended up go­ing a step fur­ther and ac­ci­den­tally en­gi­neered an en­zyme which was even bet­ter at break­ing down PET plas­tics,” said the re­port in the Pro­ceed­ings of the Na­tional Academy of Sciences, a peer-re­viewed US jour­nal.

Us­ing a su­per-pow­er­ful X-ray, 10 bil­lion times brighter than the Sun, they were able to make an ul­tra­high-res­o­lu­tion three-di­men­sional model of the en­zyme.

Sci­en­tists from the Uni­ver­sity of South Florida and the Uni­ver­sity of Camp­inas in Brazil did com­puter mod­el­ing which showed PETase looked sim­i­lar to an­other en­zyme, cuti­nase, found in fun­gus and bac­te­ria.

One area of the PETase was a bit dif­fer­ent, though, and re­searchers hy­poth­e­sized that this was the part that al­lowed it to de­grade man-made plas­tic.

So they mu­tated the PETase ac­tive site to make it more like cuti­nase, and un­ex­pect­edly found that this mu­tant en­zyme was even bet­ter than the nat­u­ral PETase at break­ing down PET.

Re­searchers say they are now work­ing on fur­ther im­prove­ments to the en­zyme, with the hope of even­tu­ally scal­ing it up for in­dus­trial use in break­ing down plas­tics.

“Al­though the im­prove­ment is mod­est, this unan­tic­i­pated dis­cov­ery sug­gests that there is room to fur­ther im­prove these en­zymes, mov­ing us closer to a re­cy­cling so­lu­tion for the ever-grow­ing moun­tain of dis­carded plas­tics,” said study au­thor John McGee­han, pro­fes­sor in the School of Bi­o­log­i­cal Sciences at Portsmouth.

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