Fast atom Bombardment Mass Spectrometry of Nucleosides,Nucleotides and Oligonucleotides

Abstract

Fast atom bombardment (FAB) mass spectrometry, a new ionization technique, has been applied to a variety of polar, nonvolatile compounds with considerable success. Current literature regarding the analysis of nucleosides, nucleotides and oligonucleotides using FAB is reviewed.     

Effect of Metal Cations on the Viscosity of a Pectin-Like Capsular Polysaccharide from the Cyanobacterium Microcystis flos-aquae C3-40

The properties of purified capsular polysaccharide from the cyanobacterium Microcystis flos-aquae C3-40 were examined by capillary viscometry. Capsule suspensions exhibited similar viscosities between pH 6 and 10 but were more viscous at pH <=4 than at pH 6 to 11. At pH 7, a biphasic effect of metal ion concentration on capsule viscosity was observed: (i) capsule viscosity increased with increasing metal ion concentration until a maximal viscosity occurred at a specific concentration that was a reproducible characteristic of each metal ion, and (ii) the viscosity decreased with further addition of that ion. Because the latter part of the biphasic curve was complicated by additional factors (especially the precipitation or gelation of capsule by divalent metal ions), the effects of various metal chlorides were compared for the former phase in which capsule viscosity increased in the presence of metal ions. Equivalent increases in capsule viscosity were observed with micromolar concentrations of divalent metal ions but only with 10 to 20 times greater concentrations of Na(sup+). The relative abilities of various metal salts to increase capsule viscosity were as follows: CdCl(inf2), Pb(NO(inf3))(inf2), FeCl(inf2) > MnCl(inf2) > CuCl(inf2), CaCl(inf2) >> NaCl. This pattern of metal efficacy resembles known cation influences on the structural integrity of capsule in naturally occurring and cultured M. flos-aquae colonies. The data are the first direct demonstration of an interaction between metal ions and purified M. flos-aquae capsule, which has previously been proposed to play a role in the environmental cycling of certain multivalent metals, especially manganese. The M. flos-aquae capsule and the plant polysaccharide pectin have similar sugar compositions but differ in their relative responses to various metals, suggesting that capsular polysaccharide could be a preferable alternative to pectin for certain biotechnological applications.     

The influence of the genes An1, An2, and An4 on the activity of the enzyme UDP-glucose:Flavonoid 3-O-glucosyltransferase in flowers of Petunia hybrida

A relation between gene dosage and UDP-glucose:flavonoid 3-O-glucosyl-transferase (UFGT) activity was found in homozygous dominant and recessive parental lines and their F₁ progeny for both of the genes An1 and An2. In both F₂ crosses, progeny plants could be classified as belonging to groups showing either a low or a medium to high UFGT activity. Test crosses showed that heterozygous and homozygous dominant plants were present throughout the medium- to high-active group. The dosage relation in F₂ plants is most probably confounded by the segregation of modifiers. Thermal inactivation experiments indicated that structurally different UFGT enzymes are formed in homozygous dominant lines as well as in lines homozygous recessive for either An1 or An2. Lines homozygous recessive for the gene An4 contain a UFGT with a half-life time at 55° C of less than 8 min, whereas UFGTs from lines homozygous dominant for An4 show a half-life time of 25 min or above, with one exception. This relation was confirmed in the F₂ progeny; heterozygotes for An4 showed an intermediate half-life time. It is concluded that An4 might be the structural gene for the enzyme; An1 and An2 are both regulatory genes. UFGT activity in flowerbuds of An4/An4 plants seems to be lower than in an4/an4 plants. Anthers of flowers of an4/an4 lines, however, are virtually devoid of UFGT activity.     

Genetic control of the conversion of dihydroflavonols into flavonols and anthocyanins in flowers of Petunia hybrida

Petunia hybrida mutants, homozygous recessive for one of the genes An1, An2, An6, or An9 do not show anthocyanin synthesis in in vitro complementation experiments per se (see also Kho et al. 1977). Extracts of flowers of these mutants all provoke anthocyanin synthesis in isolated petals of an an3an3 mutant. Mutants homozygous recessive for one of the genes An1, An2, An6, or An9 and homozygous recessive for F1 accumulate dihydroflavonols in comparable amounts. The synthesis of dihydromyricetin is blocked in an1an1 mutants, which indicates a regulating effect of the gene An1 on the gene Hfl. Similar mutants, but dominant for F1, accumulate flavonols (kaempferol and quercetin) instead of dihydroflavonols. Myricetin is accumulated in minor amounts and not at all in an1an1 mutant. Furthermore, the synthesis of this flavonol is not controlled by the gene F1. The synthesis of cyanidin (derivatives) is greatly reduced when flavonols are synthesized (F1 dominant). In mutants dominant for Ht1 and Hf1 and thus able to synthesize cyanidin (derivatives) and delphinidin (derivatives), predominantly delphinidin (derivatives) are synthesized. The results indicate that kaempferol (derivatives), quercetin (derivatives), and delphinidin (derivatives) are the main endproducts of flavonoid biosynthesis in Petunia hybrida.     

Hydroxylation of cinnamic acids and flavonoids during biosynthesis of anthocyanins in Petunia hybrida Hort.

The effect of hydroxylation genes on the hydroxylation of intermediates of flavonoid biosynthesis in Petunia hybrida is reported. In mutants homozygous recessive, for the gene An9, dihydroflavonols accumulate. The number of hydroxyl groups in the B-ring is determined by the hydroxylation genes Htl and Hfl. A similar effect of Htl and (probably) Hfl occurs in flavanone-accumulating mutants, homozygous recessive for the gene An3. Mutants dominant for Hfl probably accumulate a 5,7,3,4,5-pentahydroxyflavanone. The mutant W43, homozygous recessive for the gene An5, is blocked in an early flavonoid biosynthesis step. It accumulates p-coumaric acid together with caffeic acid. The hydroxylation genes Htl and Hfl, however, are also homozygous recessive, which indicates that the hydroxylation of p-coumaric acid to caffeic acid or derivatives of these compounds is not controlled by Htl. The accumulation of caffeic acid was observed in all mutants investigated so far, regardless of which hydroxylation genes were dominant or recessive. We conclude that hydroxylations involved in anthocyanin biosynthesis occur at the C15 level.Deceased