Search results for "Secologanin"

Deoxysarpagine Hydroxylase — A Novel Enzyme Closing a Short Side Pathway of Alkaloid Biosynthesis in Rauvolfia

2002

Microsomal preparations from cell suspension cultures of the Indian plant Rauvolfia serpentina catalyze the hydroxylation of deoxysarpagine under formation of sarpagine. The newly discovered enzyme is dependent on NADPH and oxygen. It can be inhibited by typical cytochrome P450 inhibitors such as cytochrome c, ketoconazole, metyrapone, tetcyclacis and carbon monoxide. The CO-effect is reversible with light (450 nm). The data indicate that deoxysarpagine hydroxylase is a novel cytochrome P450-dependent monooxygenase. A pH optimum of 8.0 and a temperature optimum of 35 degrees C were determined. K(m) values were 25 microM for NADPH and 7.4 microM for deoxysarpagine. Deoxysarpagine hydroxylase…

The origin of the serpentine endemic Minuartia laricifolia subsp. ophiolitica by vicariance and competitive exclusion.

2013

Serpentine soils harbour a unique flora that is rich in endemics. We examined the evolution of serpentine endemism in Minuartia laricifolia, which has two ecologically distinct subspecies with disjunct distributions: subsp. laricifolia on siliceous rocks in the western Alps and eastern Pyrenees and subsp. ophiolitica on serpentine in the northern Apennines. We analysed AFLPs and chloroplast sequences from 30 populations to examine their relationships and how their current distributions and ecologies were influenced by Quaternary climatic changes. Minuartia laricifolia was divided into four groups with a BAPS cluster analysis of the AFLP data, one group consisted only of subsp. ophiolitica, …

Purification, partial amino acid sequence and structure of the product of raucaffricine-O-β-d-glucosidase from plant cell cultures of Rauwolfia serpe…

1999

Plant cell suspension cultures of Rauwolfia produce within 1 week approximately 250 nkat/l of raucaffricine-O-beta-D-glucosidase. A five step procedure using anion exchange chromatography, chromatography on hydroxylapatite, gel filtration and FPLC-chromatography on Mono Q and Mono P delivered in a yield of 0.9% approximately 1200-fold enriched glucosidase. A short protocol employing DEAE sepharose, TSK 55 S gel chromatography and purification on Mono Q gave a 5% recovery of glucosidase which was 340-fold enriched. SDS-PAGE showed a Mr for the enzyme of 61 kDa. The enzyme is not glycosylated. Structural investigation of the enzyme product, vomilenine, demonstrated that the alkaloid exists in…

In vivo NMR at 800 MHz to monitor alkaloid metabolism in plant cell cultures without tracer labeling.

2001

Isolation and Structure Elucidation of a New Indole Alkaloid from Rauvolfia serpentina Hairy Root Culture: The First Naturally Occurring Alkaloid of …

2002

A new monoterpenoid indole alkaloid, 10-hydroxy- N(alpha)-demethyl-19,20-dehydroraumacline ( 1), was isolated as a mixture of E- and Z-isomers from hairy root culture of Rauvolfia serpentina Benth. ex Kurz (Apocynaceae) and the structure was determined by 1D and 2D NMR analyses. The new indole alkaloid represents the first naturally occurring alkaloid of the raumacline group and its putative biosynthetical pathway is discussed.

In vivo monitoring of alkaloid metabolism in hybrid plant cell cultures by 2D cryo-NMR without labelling

2003

Non-invasive measurements of alkaloid metabolism in plant cell suspension cultures of a somatic hybrid from Rauvolfia serpentina Benth. ex Kurz and Rhazya stricta Decaisne were carried out. When cell samples were taken sequentially from a stock feeding experiment, measuring times for in vivo NMR of 40 min were sufficient for following conversions of alkaloids at the natural abundance of 13C. Degradation of ajmaline added to the cells at 1.6 mM concentration to raumacline could be monitored after 96 h on a standard 800 MHz NMR instrument (Avance 800). Feeding vinorine an intermediate of ajmaline biosynthesis at 1.8 mM showed with a 500 MHz CryoProbe that the alkaloid enters two metabolic rou…

Structures of Alkaloid Biosynthetic Glucosidases Decode Substrate Specificity

2011

Two similar enzymes with different biosynthetic function in one species have evolved to catalyze two distinct reactions. X-ray structures of both enzymes help reveal their most important differences. The Rauvolfia alkaloid biosynthetic network harbors two O-glucosidases: raucaffricine glucosidase (RG), which hydrolyses raucaffricine to an intermediate downstream in the ajmaline pathway, and strictosidine glucosidase (SG), which operates upstream. RG converts strictosidine, the substrate of SG, but SG does not accept raucaffricine. Now elucidation of crystal structures of RG, inactive RG-E186Q mutant, and its complexes with ligands dihydro-raucaffricine and secologanin reveals that it is the…

Molecular Architecture of Strictosidine Glucosidase: The Gateway to the Biosynthesis of the Monoterpenoid Indole Alkaloid Family[W]

2007

Abstract Strictosidine β-d-glucosidase (SG) follows strictosidine synthase (STR1) in the production of the reactive intermediate required for the formation of the large family of monoterpenoid indole alkaloids in plants. This family is composed of ∼2000 structurally diverse compounds. SG plays an important role in the plant cell by activating the glucoside strictosidine and allowing it to enter the multiple indole alkaloid pathways. Here, we report detailed three-dimensional information describing both native SG and the complex of its inactive mutant Glu207Gln with the substrate strictosidine, thus providing a structural characterization of substrate binding and identifying the amino acids …

The Structure of Rauvolfia serpentina Strictosidine Synthase Is a Novel Six-Bladed β-Propeller Fold in Plant Proteins

2006

Abstract The enzyme strictosidine synthase (STR1) from the Indian medicinal plant Rauvolfia serpentina is of primary importance for the biosynthetic pathway of the indole alkaloid ajmaline. Moreover, STR1 initiates all biosynthetic pathways leading to the entire monoterpenoid indole alkaloid family representing an enormous structural variety of ∼2000 compounds in higher plants. The crystal structures of STR1 in complex with its natural substrates tryptamine and secologanin provide structural understanding of the observed substrate preference and identify residues lining the active site surface that contact the substrates. STR1 catalyzes a Pictet-Spengler–type reaction and represents a novel…

New Alkaloids of the Sarpagine Group from Rauvolfia serpentina Hairy Root Culture

2002

Three new monoterpenoid indole alkaloids, 19(S),20(R)-dihydroperaksine (1), 19(S),20(R)-dihydroperaksine-17-al (2), and 10-hydroxy-19(S),20(R)-dihydroperaksine (3), along with 16 known alkaloids 4-19 were isolated from hairy root culture of Rauvolfia serpentina, and their structures were elucidated by 1D and 2D NMR analyses. Taking into account the stereochemistry of the new alkaloids and results of preliminary enzymatical studies, the putative biosynthetical relationships between the novel alkaloids are discussed.