It was found that at neutral pH the hydroxylation reaction rate of phenol was accelerated with an increase of the amounts of 1,4 quinone (1,4 BQ). This acceleration was ascribed to the formation of semiquinone from 1,...It was found that at neutral pH the hydroxylation reaction rate of phenol was accelerated with an increase of the amounts of 1,4 quinone (1,4 BQ). This acceleration was ascribed to the formation of semiquinone from 1,4 BQ. The semiquinone and 1,4 BQ were suggested to play a role of actual oxidant (electron transfer) in the catalytic cycle. With further reaction, most 1,4 BQ was converted into 1,4 hydroquinone (HQ) and the corresponding mechanism was proposed.展开更多
Metalloproteins have inspired chemists for many years to synthesize artificial catalysts that mimic native enzymes.As a complementary approach to studying native enzymes or making synthetic models,biosynthetic approac...Metalloproteins have inspired chemists for many years to synthesize artificial catalysts that mimic native enzymes.As a complementary approach to studying native enzymes or making synthetic models,biosynthetic approach using small and stable proteins to model native enzymes has offered advantages of incorporating non-covalent secondary sphere interactions under physiological conditions.However,most biosynthetic models are restricted to natural amino acids.To overcome this limitation,incorporating unnatural amino acids into the biosynthetic models has shown promises.In this review,we summarize first synthetic,semisynthetic and biological methods of incorporates unnatural amino acids(UAAs)into proteins,followed by progress made in incorporating UAAs into both native metalloproteins and their biosynthetic models to fine-tune functional properties beyond native enzymes or their variants containing natural amino acids,such as reduction potentials of azurin,O_2 reduction rates and percentages of product formation of HCO models in Mb,the rate of radical transport in ribonucleotide reductase(RNR)and the proton and electron transfer pathways in photosystemⅡ(PSⅡ).We also discuss how this endeavour has allowed systematic investigations of precise roles of conserved residues in metalloproteins,such as Metl21 in azurin,Tyr244 that is cross-linked to one of the three His ligands to CuB in HCO,Tyr122,356,730 and 731 in RNR and TyrZ in PSⅡ.These examples have demonstrated that incorporating UAAs has provided a new dimension in our efforts to mimic native enzymes and in providing deeper insights into structural features responsible high enzymatic activity and reaction mechanisms,making it possible to design highly efficient artificial catalysts with similar or even higher activity than native enzymes.展开更多
文摘It was found that at neutral pH the hydroxylation reaction rate of phenol was accelerated with an increase of the amounts of 1,4 quinone (1,4 BQ). This acceleration was ascribed to the formation of semiquinone from 1,4 BQ. The semiquinone and 1,4 BQ were suggested to play a role of actual oxidant (electron transfer) in the catalytic cycle. With further reaction, most 1,4 BQ was converted into 1,4 hydroquinone (HQ) and the corresponding mechanism was proposed.
基金supported by the US National Science Foundation(CHE-1413328)the Major State Basic Research Program of China(2015CB856203)+1 种基金the National Natural Science Foundation of China (21325211,31500641)theTianjinMunicipalGrant(13ZCZDSY04800, 14ZCZDSY00059,14JCYBJC43400)
文摘Metalloproteins have inspired chemists for many years to synthesize artificial catalysts that mimic native enzymes.As a complementary approach to studying native enzymes or making synthetic models,biosynthetic approach using small and stable proteins to model native enzymes has offered advantages of incorporating non-covalent secondary sphere interactions under physiological conditions.However,most biosynthetic models are restricted to natural amino acids.To overcome this limitation,incorporating unnatural amino acids into the biosynthetic models has shown promises.In this review,we summarize first synthetic,semisynthetic and biological methods of incorporates unnatural amino acids(UAAs)into proteins,followed by progress made in incorporating UAAs into both native metalloproteins and their biosynthetic models to fine-tune functional properties beyond native enzymes or their variants containing natural amino acids,such as reduction potentials of azurin,O_2 reduction rates and percentages of product formation of HCO models in Mb,the rate of radical transport in ribonucleotide reductase(RNR)and the proton and electron transfer pathways in photosystemⅡ(PSⅡ).We also discuss how this endeavour has allowed systematic investigations of precise roles of conserved residues in metalloproteins,such as Metl21 in azurin,Tyr244 that is cross-linked to one of the three His ligands to CuB in HCO,Tyr122,356,730 and 731 in RNR and TyrZ in PSⅡ.These examples have demonstrated that incorporating UAAs has provided a new dimension in our efforts to mimic native enzymes and in providing deeper insights into structural features responsible high enzymatic activity and reaction mechanisms,making it possible to design highly efficient artificial catalysts with similar or even higher activity than native enzymes.
