The substitution pattern of anthocyanin pigments is a main determinant of f lower color. Flavonoid 3,5-hydroxylase (F35H) is a cytochrome P450 enzyme (Cyt P450) that catalyzes the 3,5-hydroxylation of dihydrof lavonols, the precursors of purple anthocyanins. Species such as rose and carnation lack F35H activity and are, therefore, unable to generate purple or blue f lowers. Petunia, on the other hand, contains two loci, termed hf1 and hf2, that encode a Cyt P450 with F35H activity. Here we report the identification of an additional petunia gene that is required for 3,5 substitution of anthocyanins and purple f lower colors. It encodes a cytochrome b 5 and is expressed exclusively in the f lower. Inactivation of the gene by targeted transposon mutagenesis reduced F35H enzyme activity and the accumulation of 5-substituted anthocyanins, resulting in an altered f lower color. However, no phenotypic effect on the activity of other Cyt P450s, involved in the synthesis of hormones or general phenylpropanoids, was observed. These data provide in vivo evidence for the regulation of the activity of specific Cyt P450s by a cytochrome b 5 .

The endogenous ABA contents of dormant and nondormant barley grains were determined following application of different compounds to break dormancy. The chemicals used for breaking of dormancy in intact dormant grains were weak and strong acids, alcohols, hydrogen peroxide, cyanide, nitrate, salicylic acid, gibberellic acid and fusicoccin. The dormancy-breaking compounds could be classified into two major groups: compounds that caused a decrease in endogenous ABA (class I) and compounds which did not affect endogenous ABA (class II). Class I compounds included gibberellic acid, ethanol, hydrogen peroxide, nitrate, salicylic acid; class II compounds were fusicoccin, acid (H2SO4), sodium azide, n-caproic acid. In addition, these dormancy-breaking compounds were able to stimulate the germination rate when applied to embryos isolated from dormant grains. The concentrations necessary for stimulation of germination of isolated embryos were much lower than the concentrations for breaking the dormancy of intact grains. After embryos were isolated from dormant grains and incubated in water, ABA was determined in both embryos and in the incubation media. The class I compounds stated above also reduced ABA content in the incubation medium of isolated embryos, while class II compounds had no effect on ABA content of the medium. External application of ABA could overcome the effect of dormancy-breaking compounds of class I but not of class II. The results suggest that in the presence of the agents belonging to class II, ABA responsiveness of isolated embryos from dormant grains is decreased, compared to nontreated embryos.

Not only mechanistically interesting but also preparatively attractive‐for example, because of inexpensive starting materials‐the olefmation of aldehydes such as 1 catalyzed by Lewis acids is described here for the first time. This surprising one‐pot reaction leads to styrene 2.

The synthesis and application of a labelling reagent for the column liquid chromatographic determination of carboxylic acids using chemilurninescence (CL) detection is described. Dansyl chloride is first reacted with an excess of piperazine and then with bromoacetic acid. The resulting label, N-(bromoacetyl)-N'-[5-(dimethylamino)naphthalene-I -sulphonyl]piperazine (dansyl-BAP), which contains a reactive bromoacetamide group, is stable for at least 6 months. Pre-column derivatization is carried out in polar aprotic media in 30 min at room temperature for aliphatic acids, and in 30 min at 55 "C for aromatic acids, i n the presence of 18-crown-6 and potassium hydrogen carbonate as a base catalyst. After derivatization, excess of dansyl-BAP is converted into a relatively polar product by reaction with thymine and is subsequently separated from the derivatized analytes on a silica cartridge. High-performance liquid chromatography is performed on c 1 8 and c8 columns with acetonitrile-water mixtures as the eluent. Fluorescence detection is carried out at an excitation wavelength of 255 n m using a 470 n m emission cut-off filter. Chemiluminescence detection is carried out by adding bis(2-nitrophenyl) oxalate and hydrogen peroxide dissolved in acetonitrile t o the column effluent. The fluorescence detection limit is 0.8-1 pmol for acids such as substituted benzoic acids and the drugs naproxen and ibuprofen; the CL detection limit is 25 fmol for retinoic acid, a vitamin A precursor.

apt = -145 gegen [PtC1,]2-1121) durch einen Thioharnstoffliganden in 5 fuhrt erwartungsgemal3 zu einer starkeren Abschirmung des Pt-Kerns und somit zu einer Hochfeldverschiebung der '95Pt-Resonanz.Das primare Zielmolekul ini Wirkungsmechanismus von Pt-Antitumorverbindungen ist chromosomale DNA[13]. In einer Modellreaktion setzten wir 5 rnit 5'-Guanosinmonophosphat (5'-GMP), einem einfachen monomeren Nucleinsaurefragment, unter physiologischen Bedingungen um. Uber erste Ergebnisse dieser Untersuchungen sowie iibcr anstehende Aktivitatsstudien mit 5 an der P388-Leukimie in vivo sol1 jedoch an anderer Stelle berichtet werden. ExperirnentellesDie 'H-und '95Pt-NMR-Messungen wurden an einem Bruker-WMSOO-NMR-Spektrometer bei 300 bzw. 64 MHz durchgefiihrt, die Messung der IR-und Eern-IR-Spektren (KBr-bzw. Polyethylen-PreDlinge) an einem Bruker-IFS-13 3v-FT-IR-Spektrometer. Synthese von 5: Zu einer Losung von 0.167 g (0.5 mmol) 4 [6] in 5 mL wasserfreiem Methanol werden 0.150 g (0.5 mmol) Cisplatin 1 [14] gegehen. Die Suspension wird 2 h bei Raumtemperatur unter AusschluR von Licht geruhrt. Die entstandene orangegelbe Losung wird rnit wasserfreiem Diethylether bis zur einsetzcnden Triibung versetzt. Nach mehrtagigem Stehen im Kiihlschrank fallt 5 in Form eines orangefarbenen. mikrokristallinen Niederschlags an, der abfiltriert und mit Diethylether gewaschen wird. 5 kristallisiert als 5 . 0.5 CH,OH, was durch CHN-Analysen bestltigt wird. Es werden 0.176 g Produkt erhalten (68 YO).