Acylated Forms Research Articles

ANTHOCYANINS IN THE PERICARP AND COLEOPTILES OF PURPLE-SEEDED RYE

The major anthocyanins in the pericarp of purple-seeded rye (Secale cereale) cultivars were found to be cyanidin 3-glucosides, peonidin 3-glucosides, and acylated forms of these glycosides. Trace amounts of cyanidin 3-rutinoside, peonidin 3-rutinoside, and the corresponding acylated derivatives were detected. The ratio of the aglycones varied between cultivars. Similar differences were found in the proportion of the acylated forms. Only cyanidin 3-rutinoside was present in the coleoptiles, whereas the first leaves contained only cyanidin 3-glucoside.

The genetic control of anthocyanin biosynthesis by homoeologous chromosomes in wheat

SUMMARYColeoptile anthocyanin pigmentation in the hexaploid variety of wheat, Hope, is due to at least eight anthocyanins including four acylated forms. All are derivatives of either cyanidin or peonidin. Two homoeologous chromosomes, 7A and 7B, are involved in anthocyanin production. Both chromosomes carry genes that promote the synthesis of the same anthocyanins from flavonoid precursors. The roles of chromosomes 7A and 7B in anthocyanin biosynthesis and the consequences of interallelic interaction and dominance of possibly homoeologous loci are discussed.

Enzymatische Glucosylierung von pflanzlichen Sterinen

A particulate enzyme preparation from dark grown mung bean shoots incorporates the glucosyl unit from UDP- (14C) -glucose into lipophilic products. These were identified by thin layer chromatography as a mixture of β-sitosterylglucoside and stigmasteryl-glucoside (80%) as well as the acylated forms of these substances (20%). The reaction is almost linear with time up to 10 minutes, optimal at pH values between 6.3 and 6.6 and does not require divalent cations. The acceptor sterols were shown to be present in the particulate preparation; exogenous sterols do not seem to act as acceptors. The same particulate enzyme preparation can also synthesize cellulose from UDPG 15 and lipid intermediates for its biosynthesis have been predicted 20. It appeared possible, therefore, that the sterylglucosides act as such intermediates. This, however, does not seem to be the case, since dilution of the UDP- (14C) -Glucose with unlabelled UDPG as well as its hydrolysis with phosphodiesterase within the course of an experiment demonstrates that the glucosyl units of the sterylglucosides show no turnover.

Biosynthesis of Mannophosphoinositides by Mycobacterium phlei: Enzymatic Acylation of the Dimannophosphoinositides

Abstract The phosphatidylmyoinositol dimannosides (dimannophosphoinositides) of mycobacteria occur in multiply acylated forms, two fatty acids being attached to the glycerol part of the phospholipid and additional fatty acids being esterified to available hydroxyls on the mannose or myoinositol parts. This report describes a particulate enzyme in Mycobacterium phlei which is specific in its ability to incorporate labeled fatty acids into the dimannophosphoinositides. The acylation requires coenzyme A and ATP, and it is shown that fatty acyl coenzyme A can replace these two substances in the reaction. The fatty acid specificity of the enzyme is broader than the range of fatty acids found in the lipids in the cell; in addition to palmitic and tuberculostearic acid, myristic, stearic, and oleic acid are effective substrates. The first acylation step has been clearly shown. Pure dimannophosphoinositide C (two fatty acids) is acylated by palmityl coenzyme A to yield dimannophosphoinositide B (three fatty acids). The further acylation of the latter to dimannophosphoinositide A (four fatty acids) is observed in short incubation periods, but this is followed by the conversion (deacylation) of the product to isomeric forms of dimannophosphoinositide B and C. Evidence is presented that this occurs via still more highly acylated members of the dimannophosphoinositide family. The enzyme system in M. phlei that is responsible for the biosynthesis of the dimannophosphoinositides from phosphatidylmyoinositol and GDP-mannose has been examined in more detail. Evidence has been obtained for heterogeneity in the dimannophosphoinositide B component of the products of this reaction in Mycobacterium tuberculosis, which provides a further indication for the existence of isomeric forms of these lipids. An over-all scheme is suggested for the biosynthesis of these complex lipids in Mycobacterium species.