The authors have studied the effect of a magnetic field on Baldwin＇s rules. The authors have proposed a new mechanism that takes into account the effect of the angle and energy endo- or exo-cyclization. The authors p...The authors have studied the effect of a magnetic field on Baldwin＇s rules. The authors have proposed a new mechanism that takes into account the effect of the angle and energy endo- or exo-cyclization. The authors propose to extend the rule Bouldwin not only for sp^3-, sp^2- and sp- orbits, but and for d^1 - d^10 and f^1 - f^14 elements of I-VIII of the Periodic table.展开更多
Pyran-and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans,respectively,exhibiting diverse physiological and medical bioactivities.However,the biosynthetic mechanisms for their core str...Pyran-and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans,respectively,exhibiting diverse physiological and medical bioactivities.However,the biosynthetic mechanisms for their core structures remain poorly understood.Here we combined multiomics analyses of biosynthetic enzymes in Peucedanum praeruptorum and in vitro functional verification and identified two types of key enzymes critical for pyran and furan ring biosynthesis in plants.These included three distinct P.praeruptorum prenyltransferases(PpPT1e3)responsible for the prenylation of the simple coumarin skeleton 7 into linear or angular precursors,and two novel CYP450 cyclases(PpDC and PpOC)crucial for the cyclization of the linear/angular precursors into either tetrahydropyran or tetrahydrofuran scaffolds.Biochemical analyses of cyclases indicated that acid/base-assisted epoxide ring opening contributed to the enzyme-catalyzed tetrahydropyran and tetrahydrofuran ring refactoring.The possible acid/base-assisted catalytic mechanisms of the identified cyclases were theoretically investigated and assessed using site-specific mutagenesis.We identified two possible acidic amino acids Glu303 in PpDC and Asp301 in PpOC as vital in the catalytic process.This study provides new enzymatic tools in the epoxide formation/epoxide-opening mediated cascade reaction and exemplifies how plants become chemically diverse in terms of enzyme function and catalytic process.展开更多
文摘The authors have studied the effect of a magnetic field on Baldwin＇s rules. The authors have proposed a new mechanism that takes into account the effect of the angle and energy endo- or exo-cyclization. The authors propose to extend the rule Bouldwin not only for sp^3-, sp^2- and sp- orbits, but and for d^1 - d^10 and f^1 - f^14 elements of I-VIII of the Periodic table.
基金National Key Research and Development Program of China (2018YFA0902000)the key project at central government level:the ability establishment of sustainable use for valuable Chinese medicine resources(2060302,China)+3 种基金the open foundation of Shaanxi University of Chinese Medicine state key laboratory of R&D of Characteristic Qin Medicine Resources (SUCM-QM202202,China)the fund of Traditional Chinese Medicine Institute of Anhui Dabie Mountain (TCMADM-2023-18,China)National Natural Science Foundation of China (32070364)Hainan Provincial Natural Science Foundation of China(2019RC309)
文摘Pyran-and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans,respectively,exhibiting diverse physiological and medical bioactivities.However,the biosynthetic mechanisms for their core structures remain poorly understood.Here we combined multiomics analyses of biosynthetic enzymes in Peucedanum praeruptorum and in vitro functional verification and identified two types of key enzymes critical for pyran and furan ring biosynthesis in plants.These included three distinct P.praeruptorum prenyltransferases(PpPT1e3)responsible for the prenylation of the simple coumarin skeleton 7 into linear or angular precursors,and two novel CYP450 cyclases(PpDC and PpOC)crucial for the cyclization of the linear/angular precursors into either tetrahydropyran or tetrahydrofuran scaffolds.Biochemical analyses of cyclases indicated that acid/base-assisted epoxide ring opening contributed to the enzyme-catalyzed tetrahydropyran and tetrahydrofuran ring refactoring.The possible acid/base-assisted catalytic mechanisms of the identified cyclases were theoretically investigated and assessed using site-specific mutagenesis.We identified two possible acidic amino acids Glu303 in PpDC and Asp301 in PpOC as vital in the catalytic process.This study provides new enzymatic tools in the epoxide formation/epoxide-opening mediated cascade reaction and exemplifies how plants become chemically diverse in terms of enzyme function and catalytic process.
