Department Environmental Chemistry

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   libraryUrl => '' (0 chars)

array(3 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=21649, pid=124)
      originalId => protected21649 (integer)
      authors => protected'Egli, C. M.; Stravs, M. A.; Janssen, E. M.&nbs
         p;L.' (80 chars)
      title => protected'Inactivation and site-specific oxidation of aquatic extracellular bacterial 
         leucine aminopeptidase by singlet oxygen' (116 chars)
      journal => protected'Environmental Science and Technology' (36 chars)
      year => protected2020 (integer)
      volume => protected54 (integer)
      issue => protected'22' (2 chars)
      startpage => protected'14403' (5 chars)
      otherpage => protected'14412' (5 chars)
      categories => protected'' (0 chars)
      description => protected'Extracellular enzymes are master recyclers of organic matter, and to predict
          their functional lifetime, we need to understand their environmental transf
         ormation processes. In surface waters, direct and indirect photochemical tra
         nsformation is a known driver of inactivation. We investigated molecular cha
         nges that occur along with inactivation in aminopeptidase, an abundant class
          of extracellular enzymes. We studied the inactivation kinetics and localize
         d oxidation caused by singlet oxygen, <sup>1</sup>O<sub>2</sub>, a major pho
         tochemically derived oxidant toward amino acids. Aminopeptidase showed secon
         d-order inactivation rate constants with <sup>1</sup>O<sub>2</sub> comparabl
         e to those of free amino acids. We then visualized site-specific oxidation k
         inetics within the three-dimensional protein and demonstrated that fastest o
         xidation occurred around the active site and at other reactive amino acids. 
         However, second-order oxidation rate constants did not correlate strictly wi
         th the <sup>1</sup>O<sub>2</sub>-accessible surface areas of those amino aci
         ds. We inspected site-specific processes by a comprehensive suspect screenin
         g for 723,288 possible transformation products. We concluded that histidine 
         involved in zinc coordination at the active site reacted slower than what wa
         s expected by its accessibility, and we differentiated between two competing
          reaction pathways of <sup>1</sup>O<sub>2</sub> with tryptophan residues. Th
         is systematic analysis can be directly applied to other proteins and transfo
         rmation reactions.' (1538 chars)
      serialnumber => protected'0013-936X' (9 chars)
      doi => protected'10.1021/acs.est.0c04696' (23 chars)
      uid => protected21649 (integer)
      _localizedUid => protected21649 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected21649 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=20604, pid=124)
      originalId => protected20604 (integer)
      authors => protected'Egli,&nbsp;C.&nbsp;M.; Natumi,&nbsp;R.&nbsp;S.; Jones,&nbsp;M.&nbsp;R.; Jans
         sen,&nbsp;E.&nbsp;M.&nbsp;-L.' (105 chars)
      title => protected'Inhibition of extracellular enzymes exposed to cyanopeptides' (60 chars)
      journal => protected'Chimia' (6 chars)
      year => protected2020 (integer)
      volume => protected74 (integer)
      issue => protected'3' (1 chars)
      startpage => protected'122' (3 chars)
      otherpage => protected'128' (3 chars)
      categories => protected'aquatic enzymes; biogeochemical cycling; cyanobacteria; harmful algae bloom;
          microbial loop' (91 chars)
      description => protected'Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive sec
         ondary metabolites including cyanopeptides that pose ecological and human he
         alth risks. Only adverse effects of one class of cyanopeptides, microcystins
         , have been studied extensively and have consequently been included in water
          quality assessments. Inhibition is a commonly observed effect for enzymes e
         xposed to cyanopeptides and has mostly been investigated for human biologica
         lly relevant model enzymes. Here, we investigated the inhibition of ubiquito
         us aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are uti
         lized in the metabolism of aquatic organisms and extracellularly by heterotr
         ophic bacteria to obtain assimilable substrates. The ubiquitous occurrence o
         f hydrolytic enzymes leads to the co-occurrence with cyanopeptides especiall
         y during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkalin
         e phosphatase were exposed to cyanopeptide extracts of different cyanobacter
         ial strains (<em>Microcystis aeruginosa </em> wild type and microcystin-free
          mutant,<em> Planktothrix rubescens</em>) and purified cyanopeptides. We obs
         erved inhibition of aminopeptidase and phosphatase upon exposure, especially
          to the apolar fractions of the cyanobacterial extracts. Exposure to the dom
         inant cyanopeptides in these extracts confirmed that purified microcystins, 
         aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg
          L<sup>-1</sup> range while the phosphatase was less affected. Inhibition of
          aquatic enzymes can reduce the turnover of nutrients and carbon substrates 
         and may also impair metabolic functions of grazing organisms.' (1657 chars)
      serialnumber => protected'0009-4293' (9 chars)
      doi => protected'10.2533/chimia.2020.122' (23 chars)
      uid => protected20604 (integer)
      _localizedUid => protected20604 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected20604 (integer)modified
      pid => protected124 (integer)
   2 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=17091, pid=124)
      originalId => protected17091 (integer)
      authors => protected'Egli,&nbsp;C.&nbsp;M.; Janssen,&nbsp;E.&nbsp;M.&nbsp;L.' (55 chars)
      title => protected'A proteomics approach to trace site-specific damage in aquatic extracellular
          enzymes during photoinactivation' (109 chars)
      journal => protected'Environmental Science and Technology' (36 chars)
      year => protected2018 (integer)
      volume => protected52 (integer)
      issue => protected'14' (2 chars)
      startpage => protected'7671' (4 chars)
      otherpage => protected'7679' (4 chars)
      categories => protected'' (0 chars)
      description => protected'Extracellular enzymes are major drivers of biogeochemical nutrient and carbo
         n cycling in surface water. While photoinactivation is regarded as a major i
         nactivation process of these enzymes, the underlying molecular changes have 
         received little attention. This study demonstrate how light exposure leads t
         o a rapid loss of phosphatase, aminopeptidase and glucosidase activities of 
         biofilm samples and model enzymes. Here, an optimized proteomics approach al
         lowed simultaneous observation of inactivation and molecular changes. Site-s
         pecific fingerprints of degradation kinetics have been generated and visuali
         zed in the three-dimensional proteins. Oxidation of tryptophan, the chromoph
         oric target, initiated secondary reactions. Evidence was obtained that tyros
         ine residues act as intramolecular antioxidants, reflected in decelerated de
         cay of tryptophan- and enhanced decay of tyrosine-containing peptides. In ad
         dition, subsequent methionine oxidation and disulfide reduction contribute t
         o heterogeneous photodamage. The proximity to tryptophan residues explains >
         95% of the photodamage across the protein structures. The presence of redox-
         active organic matter or a model antioxidant in solution quenched not only p
         hotoinactivation and tryptophan oxidation but also all subsequent damage. Th
         e developed analytical approach can be applied to other research questions i
         n environmental sciences where site-specific damage in a protein is essentia
         l.' (1446 chars)
      serialnumber => protected'0013-936X' (9 chars)
      doi => protected'10.1021/acs.est.7b06439' (23 chars)
      uid => protected17091 (integer)
      _localizedUid => protected17091 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected17091 (integer)modified
      pid => protected124 (integer)