Structure and Enzymatic Reaction Mechanism of Prenyltransferases

点击翻译按钮获取中文摘要

1. On Farnesyl Diphosphate Synthase: The enzymatic reactivities of methylenediphosphonate analogues of the substrates of farnesyl diphosphate synthase showed that isopentenyl diphosphate is engaged in the enzymatic reaction as a metal-free form, whereas metal-complexed allylic substrates are the actual forms for the prenyltransferase. Both (S)- and (R)-4- methylfarnesols, Synthesized respectively from (E)- ard (Z)-3-methyl-3-pentenyl diphosphates by means of farnesyl diphosphate synthase reaction, were demonstrated to be of almost 100% enantiomeric purity.2. On Hexaprenyl Diphosphate Synthase from Micrococcus luteus B-P 26: The catalytic site of hexaprenyl diphosphate synthase is formed by cooperative interaction between the two essential components, A and B, and that cysteine and arginine residues on component B play important roles in the enzymatic activity. Formation of a stable 50-kDa complex of the two essential components of the enzyme, which represents the catalytically active s … More tate of this enzyme, is observed in the presence of inorganic pyrophosphate or one of the substrates, isopentenyl diphosphate br farnesyl diphosphate.3. On Undecaprenyl Diphosphate Synthase: The synthase reaction with (E)-3-methyl-3-pentenyl diphosphate proceeded in the same stereochemical manner as that with isopentenyl diphosphate, but it had a full stop at the stage where a single condensation of the C_6-homologue with an allylic primer is completed to form a chiral prenyl diphosphate with an extra methyl group at the 4-position. Kinetic experiments with (2Z,6E,10E)-4-methyl-geranylgeranyl diphosphate disclosed the topological capacity of the substrate-binding site of undecaprenyl diphosphate synthase.4. Polyprenyl Diphosphate Synthase from a Higher Plant: A polyprenyl diphosphate synthase catalyzing the formation of ficaprenyl-type Z,E-mixed polyprenyl diphosphates was partially purified from mulberry leaves, Morus bombysis. The stereochemistry of hydrogen elimination from the 2-position of isopentenyl diphosphate during the Z-prenyl chain formation was determined that the 2-pro-S hydrogen was lost. Less