Thesis (Doctoral)--Ludwig-Maximilians-Universität zu München, 1935.

Gene duplication and functional diversification is a central driving force in the evolution of plant biochemical diversity. However, the latter process is not well understood. Here the diversification of the plant shikimate/quinate dehydrogenase (S/QDH) gene family was investigated in order to shed light on how duplicate genes functionally diversify. The shikimate pathway is the major biosynthetic route towards the aromatic amino acids, linking vital protein biosynthesis with the production of aromatic secondary metabolites. Dehydroquinate dehydratase/shikimate dehydrogenase (SDH) encodes the central enzyme of this pathway, catalyzing the production of shikimate. Quinate is a secondary metabolite synthesized using the same precursors as shikimate by quinate dehydrogenase (QDH). Gene duplication prior to the gymnosperm / angiosperm split generated two distinct clades in seed plants separating SDH and QDH functions whereas non-seed plants have a single copy SDH. In vitro biochemical characterization of a reconstructed ancestral enzyme was performed alongside extant members separated prior to duplication (from a lycopod, a bryophyte, and a chlorophyte) and afterwards (from a gymnosperm and an angiosperm). This revealed that novel quinate biosynthetic activity was gained in seed plants, providing evidence for the diversification of gene function via neofunctionalization. However, the ability to use both NAD(H) and NADP(H) seems to have developed in both SDH and QDH clade members of angiosperms. Finally, a method is described for analysing quinate and its derivative, chlorogenic acid in transgenic Arabidopsis. / Graduate / 2021-05-11

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Lactate dehydrogenase was isolated in pure form from crude extract of the cestode Hymenoleois diminuta by heat treatment and column chromatography. The purified enzyme has a specific activity of 106 units per mg protein. The molecular weight of the purified protein was 75,000 as determined by Sephadex gel filtration and analytical ultracentrifugation. An equilibrium ultracentrifugation study suggests a subunit molecular weight of 39,000. From these data, a dimer form of the native enzyme is proposed.

Two isoenzymes of malate dehydrogenase were isolated and partially purified from the midge larva Glyptotendipes barbipes. Differential centrifugation followed by cellulose acetate and polyacrylamide gel electrophoresis revealed one isoenzyme associated with the mitochondrial fraction and another form found only in the cytoplasm.