Zur Biosynthese der Apiose

Abstract

The ethanolic extract of 8-week-old parsley plants was chromatographed on Dowex-I x 2 with a concave gradient using the buffer system of Hurlbert. After further purification on carboncelite columns, paper chromatography and high-voltage electrophoresis, 120 pmoles of a homogeneous UDP-sugar fraction were obtained. The sugars present in this fraction were identzed after acid or enzymatic hydrolysis (Crotalus adamanteus venom, acid phosphatase) by various chemical and enzymatic tests. A modified Dische test which is specific for apiose and a quantitative determination of D-xylose with D-glucose-oxidase were developed.According to the analytical investigations the UDP-sugar fraction 'had the iollowing composition (pmol) : UDP-D-glucose (84), UDP-D-galactose (27), UDP-D-xylose (4), UDP-L-arabinose (2), UDP-fructose (0.42), UDP-L-rhamnose (2.4), and UDP-apiose (0.18). The presence of UDPapiose in parsley strongly corroborates the proposed biosynthetic pathway for the formation of D-apiose via UDP-D-glucuronk acid.

Separation and identification of soluble nucleotides in cambial and young xylem tissue of Larix decidua Mill

“…UDP-arabinose and UDP-galactose may be concerned with biosynthesis ofarabinogalactans.Twointerestingnucleotidemonosaccharides that were present in the primary as well as the secondary wall fractions are UDPand ADPfructose. ADP-fructose has not previously been isolated from plant tissue, but both GDP-fructose (Selvendran & Isherwood, 1967) and UDP-fructose (Gonzalez & Pontis, 1963;Umemura, Nakamura & Funahashi, 1967;Brown & Mangat, 1967;Sandermann & Grisebach, 1968) have been found in higher plants. In two instances the latter has been isolated from tissue where it is thought to play a role in the formation of fructosans (dahlia tubers and Jerusalem artichoke).…”

“…In two instances the latter has been isolated from tissue where it is thought to play a role in the formation of fructosans (dahlia tubers and Jerusalem artichoke). However, this nucleotide has also been isolated from the leaf nodes of Impatiens bal8amina, from germinating pea seeds (Brown & Mangat, 1967) and from parsley plants (Sandermann & Grisebach, 1968), where its function is not clear. It may possibly play a role in the biosynthesis of sucrose.…”

Some Properties of Synthetic UDP(2)-fructose

“…Although this value (k=2. 8) is not the hydrolysis rate constant, but the isomerization constant, this is far higher than the hydrolysis rate constants of UDP(l)-fructose, natural UDP-fructose and related compounds.…”