Study On Biotransformation Of Phenolic And Non-phenolic Compounds By Lignin-degrading Enzyme From A White Rot Fungus SQ01

White-rot fungi is a type of microorganism,which play an important roles in the decomposition of lignin,semi-fiber,cellulose.YWhite-rot fungi decompose lignin dependent on a series of enzymes produced,these enzymes are the dominating elements in the lignin degradation system,The lignin degradation enzyme contains:laccase(Lac),mangaese peroxidase(MnP)and Lignin peroxidase(LiP).Three kings of enzymes has recently received considerable attention because of its usefulness in oxidizing phenolic and non-phenolic compounds,as well as its suitability for organic synthesis.To understand the biochemical role of white rot fungi SQ01 manganese peroxidase towards HOPDA/HOPDA derivatives and reveal the new catalytic features of MnP,white rot fungi Trametes sp.SQ01 MnP was extracted,and the purified enzymes were used in the oxidation of HOPDAs.UV-vis spectrophotometry was used to study the transformation of 10 substituted HOPDAs by manganese peroxidase and measure the steady-state kinetics parameters of manganese peroxidase against parts of HOPDAs.The molecular structures of HOPDA and HOPDA oxidation product were analyzed by Infrared spectroscopy.The results showed that Manganese peroxidase exhibited catalytic activity towards both HOPDA and halogenated HOPDA.Especially,our manganese peroxidase can use 3,8,11-3Cl HOPDA as substrate,while biphenyl hydrolase and Rhodococcus sp.R04 showed negligible activity towards this substrate.The steady-state kinetic analysis indicated that HOPDA displayed the lowest Km among 5 HOPDAs,the catalytic efficiency(kcat/Km)of 3,10-2F HOPDA was the highest.UV-visible spectroscopy analysis indicated that the maximum absorption of products of HOPDA showed blue-shift with increasing the reaction time in the visible region.Infrared analysis showed that MnP converted conjugated diene of HOPDA to monoethylenically,and cause hydroxyl on C? to disappear.A yellow laccase from the culture filtrate of Trametes sp.SQ01 has been purified and does not show absorption band around 610 nm like blue laccases.Blue laccase can oxidize a wide range of aromatic compounds and generate reactive radical intermediates,which undergo self-coupling reactions.To understand the new catalytic features of Lac.In this paper,3 kinds of phenolic compounds,including Catechol,resorcinol and hydroquinone,were catalyzed by laccase.Enzymatic polymerization contains:autologous polymerization and variant polymerization.The mechanism of polymerization and the structures of the polymers were evaluated in terms of UV-vis and Infrared spectroscopy.The molecular weights of the produced polyphenols were determined with LC-MS.The results showed that the polymerization of phenols based on laccase-catalyzed.There was no corresponding oxidative product of quinine for polymerization.Catechol?catechol and resorcinol were linked together with ether bond,four other cases of polymerization were linked together with C-C bonds.The number average molecular weights of the polyphenols ranged from 1000 to 2000 Da,corresponding to the degree of polymerization varied from 10 to 18.In this work,toluene were catalyzed by laccase.Course of reaction were measured by HPLC.Furthermore,the optimum reaction conditions has been studied by experiment of single factor.The results showed that the purified laccase transforms toluene to benzaldehyde in the absence of mediator molecules in high yields.The productivity were 78.6-93.1%in the pH range 3-9,the maximum yield under the pH 5.The optimal reaction as follows:1.5 U enzyme,insodium malonate buffer pH 5,30 ?,10 ?mol/L substrate,reaction time is 60 min.