Biosynthetic approach to modeling and understanding metalloproteins using unnatural amino acids

• Published in: Science China. Chemistry Vol. 60; no. 2; pp. 188 - 200
• Main Authors: Yu, Yang, Cui, Chang, Wang, Jiangyun, Lu, Yi
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.02.2017; Springer Nature B.V
• Subjects: Amino acids; Catalysts; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Electron transfer; Enzymes; Proteins; Reaction mechanisms; Reductases; Reviews; Ribonucleotide reductase; 圈层相互作用; 建模; 核糖核苷酸还原酶; 生物合成途径; 电子传递途径; 蛋白质模型; 金属蛋白; 非天然氨基酸; ribonucleotide reductase; heme proteins; copper proteins; protein design; metalloenzymes
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-016-0343-2

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.