PETase

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PETase (more precisely poly (ethylene terephthalate) hydrolase ) is an enzyme of the hydrolase class ( EC  3.1.1.101 ), which was discovered in 2016. It was isolated from the bacterium Ideonella sakaiensis , also discovered in 2016 , which uses PET as a carbon resource for anabolic metabolism.

The nomenclature of enzymes is based on the substrate for which it has the highest affinity. Enzymes that are able to degrade PET have been known since the 1980s, but these were enzymes that had a much higher affinity for other substrates and were able to degrade PET rather "accidentally", such as cutinases, which are the cutin of Mining mushrooms. PETase, on the other hand, has the highest affinity for PET and thus establishes a new class within hydrolases or esterases.

meaning

Ideonella sakaiensis is the first bacterium to use PET for anabolic metabolism and therefore has the greatest potential to date to be used for the biological recycling of PET.

So far, large parts of the plastic produced have been recycled pyrolytically . Although attempts were made to decompose PET using microorganisms as early as 1980, the reaction conditions were too harsh for economic industrial use. It was not until 2005 that it was possible for the first time to isolate an enzyme from Thermobifida fusca , which showed promising success. The PETase, discovered in 2016, again exceeds the T. fusca enzyme in its effectiveness by a factor of about 100.

properties

PETase catalyzes the decomposition of PET to mono (2-hydroxyethyl) terephthalic acid (MHET), which is then broken down by another enzyme, MHETase , to the monomers of PET, terephthalic acid and ethylene glycol . Its catalytic maximum is 303 K and pH 7. In the PET it attacks the carboxyl carbon of the ester, forms an acyl enzyme as an intermediate (terephthalic acid ester of Ser160) with elimination of MHET (and small amounts of BHET) and hydrolyzes the intermediate to form the Terephthalic acid end of PET.

origin

PETase was first detected in the bacterium Ideonella sakaiensis, which was also discovered in 2016 . It was found on PET bottles from a garbage dump. The specific affinity for PET is a current example of evolution. Since PET has only existed since the 1950s, it stands to reason that the bacterium Ideonella sakaiensis has adapted within about 60 years to such an extent that it can live on PET as the main supplier of carbon .

Individual evidence

  1. ↑ Exploring Renz: Search Results for "petase". Retrieved March 1, 2017 .
  2. ↑ a b M. Sato: Deterioration of filaments and films of polyethyleneterephthalate with enzymes. January 1, 1980, accessed March 1, 2017 (jp).
  3. ↑ Müller et al .: Enzymatic Degradation of Poly (ethylene terephthalate): Rapid Hydrolysis using a Hydrolase from T. fusca . In: Macromolecular Rapid Communications . tape January 26 , 2005, p. 1400-1405 .
  4. ↑ a b Shosuke Yoshida, Kazumi Hiraga, Toshihiko Takehana, Ikuo Taniguchi, Hironao Yamaji: A bacterium that degrades and assimilates poly (ethylene terephthalate) . In: Science . tape 351 , no. 6278 , March 11, 2016, ISSN  0036-8075 , p. 1196-1199 , doi : 10.1126 / science.aad6359 , PMID 26965627 .
  5. ↑ S. Tanasupawat, T. Takehana, S. Yoshida, K. Hiraga, K. Oda: Ideonella sakaiensis sp. nov., isolated from a microbial consortium that degrades poly (ethylene terephthalate). In: International journal of systematic and evolutionary microbiology. Volume 66, Number 8, August 2016, pp. 2813-2818, doi : 10.1099 / ijsem.0.001058 , PMID 27045688 .