Characterization and analysis of the antioxidant capacity of functional phenolics oxidized by Scytalidium thermophilum catalase phenol oxidase (CATPO)

Söyler, Ulviye Betül
Scytalidium thermophilum is a termophilic fungus that effectively produces the extracellular enzyme catalase phenol oxidase (CATPO). The enzyme is distinct among catalases with its bifunctionality of oxidising phenolic compounds in the absence of H2O2. CATPO is capable of oxidizing catechol, chlorogenic acid, caffeic acid and catechin which are ortho –diphenolic compounds. Diphenolic compounds are known as strong antioxidants. Catalase is one of the important antioxidant enzymes. Therefore, in this thesis the effect of CATPO on the final antioxidant capacity of the oxidized products was analysed. Antioxidant capacity measurements of oxidized and unreacted phenolic compounds were done using the two widely used methods TEAC and FRAP. CATPO oxidized catechol showed 2.4 fold increase when compared to its nonoxidized form, which was highest among others. Catechol was followed by caffeic acid, chlorogenic acid, and catechin. This finding is new to the literature and may be of importance to the antioxidant mechanism of organisms. Results have also shown that the most well known phenol oxidases, laccase and tyrosinase, do not result in such high increases in antioxidant capacity upon oxidation of the substrates tested. Due to this finding, as a possible means of applying CATPO to increase the antioxidant capacity of products daily consumed, tea was selected. Tea is the second most consumed beverage after water and it is known to possess high amounts of flavanols. Green tea is rich in catechins whereas black tea is a rich source of theaflavins and thearubigins. Fermentation is a critical process for production of good quality tea and is the key step differing between green and black tea production. During this process phenol oxidases catalyze the oxidation of polyphenolic compounds present in tea leaves to their corresponding o-quinones. Utilization of CATPO in tea samples resulted in an increase in antioxidant capacity and its effect was enhanced by an increase in brewing time. Interestingly, the addition of sugar decreased antioxidant capacity. Laccase and tyrosinase were ineffective in increasing the antioxidant capacity of tea samples.


Production of a novel bifunctional catalase-phenol oxidase of Scytalidium thermophilum in the presence of phenolic compounds
YUZUGULLU, Yonca; Ogel, ZÜMRÜT BEGÜM; BOLUKBASI, Ufuk Bakir; Çoruh, Nursen; Karakaş, Gürkan (2011-01-01)
A novel bifunctional catalase with additional phenol oxidase activity (CATPO) is produced by the thermophilic fungus, Scytalidium thermophilum, in a growth-associated manner. In order to study the biological significance of this dual enzyme in relation to phenolic compounds, 14 phenolics were tested for their effect on growth and CATPO production. It was determined that some phenolics exerted a negative effect on growth (catechol, coumaric acid, hydroquinone, kaempferol, myricetin), while others either did ...
Purification, characterization, and identification of a novel bifunctional catalase-phenol oxidase from Scytalidium thermophilum
Kocabas, Didem Sutay; Bakir, Ufuk; Phillips, Simon E. V.; McPherson, Michael J.; Ögel, Zümrüt Begüm (Springer Science and Business Media LLC, 2008-06-01)
A novel bifunctional catalase with an additional phenol oxidase activity was isolated from a thermophilic fungus, Scytalidium thermophilum. This extracellular enzyme was purified ca. 10-fold with 46% yield and was biochemically characterized. The enzyme contains heme and has a molecular weight of 320 kDa with four 80 kDa subunits and an isoelectric point of 5.0. Catalase and phenol oxidase activities were most stable at pH 7.0. The activation energies of catalase and phenol oxidase activities of the enzyme ...
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Chemical modification and inactivation of aminoglycosides by many different enzymes expressed in pathogenic bacteria are the main mechanisms of bacterial resistance to these antibiotics. In this work, we designed inhibitors that contain the 1,3-diamine pharmacophore shared by all aminoglycoside antibiotics that contain the 2-deoxystreptamine ring. A discovery library of molecules was prepared by attaching different side chains to both sides of the 1,3-diamine motif. Several of these diamines showed inhibito...
Citation Formats
U. B. Söyler, “Characterization and analysis of the antioxidant capacity of functional phenolics oxidized by Scytalidium thermophilum catalase phenol oxidase (CATPO),” Ph.D. - Doctoral Program, Middle East Technical University, 2012.