Modern methods of plant analysis
01 Jan 1964-
About: The article was published on 1964-01-01 and is currently open access. It has received 1991 citations till now.
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TL;DR: Application to acacia, chestnut and lavender honeys enabled the detection of fraud resulting from 5 to 10% addition of sugar syrups, and may be considered as a replacement of isotopic analysis, that has some limitations.
124 citations
01 Jan 1970
TL;DR: The pigments of Xanthophyceae have been identified by methods discussed in the preceding publication (Hager and Stransky 1970) and their quantities have been determined as discussed by the authors.
Abstract: SummaryThe pigments of Xanthophyceae have been identified by methods discussed in the preceding publication (Hager and Stransky 1970) and their quantities have been determined.
1.None of the examined species of Xanthophyceae contains chlorophyll b or e.2.Of the carotenes only β-carotene and, perhaps, ε-carotene are present.3.The most characteristic xanthophyll of all Xanthophyceae is vaucheriaxanthin, which normally occurs as a di-ester. It contains an allenic bond. A new structure is proposed.4.In the investigated algae — except Pleurochloris — especially diadinoxanthin appears in great quantities. It is a 5,6-epoxide compound with an alkine-bond between C7 and C8; the latter has been demonstrated by hydration to an olefinic-bond5.Diatoxanthin is detectable only in traces, but appears in larger amounts after illumination of the algae.6.In the Xanthophyceae—except Pleurochloris—a strongly absorbed xanthophyll has been found for which Strain et al. proposed the name heteroxanthin. Proposals concerning the constitution of this xanthophyll are made.7.Carotenoids occurring in small quantities in the Xanthophyceae are mostly 5,6-epoxides.8.The alga Pleurochloris holds a particular position within the Xanthophyceae. It contains their characteristic pigment—the ester of vaucheriaxanthin—and only chlorophyll a, but otherwise it possesses the pigments of the green algae, except lutein, the main xanthophyll of green algae.9.The alkine carotenoids diadinoxanthin and diatoxanthin which are dominating in the pigment composition of the Xanthophyceae show a remarkable light induced change in quantity, which is reversible in the dark. During illumination of the algae the epoxide-oxygen of diadinoxanthin is cleaved and a double bond is formed in its place. This corresponds to the second step of the violaxanthin→antheraxanthin→zeaxanthin transformation in the higher plants. The light induced changes in the amount of these pigments have been determined and compared in several Xanthophyceae. The influence of the (photosynthesis) inhibitors o-phenanthrolin and salicylaldoxim upon this cycle have been investigated.ZusammenfassungDie in Xanthophyceen vorkommenden Pigmente wurden mit den in der vorhergehenden Arbeit (Hager u. Stransky, 1970) besprochenen Methoden identifiziert, ihre Mengen bestimmt und diese in Tabellen zusammengefaßt.
1.Keine der untersuchten Xanthophyceen bestitzt Chlorophyll b oder e.2.An Carotinen ist nur β-Carotin und evtl. ε-Carotin vorhanden.3.Charakteristisches Xanthophyll aller Xanthophyceen ist das Vaucheriaxanthin, welches normalerweise als Di-Ester vorliegt. Es enthält eine Allenbindung. Ein neuer Strukturvorschlag wird begründet.4.Mengenmäßig ist in den untersuchten Algen — außer Pleurochloris — das Diadinoxanthin besonders hervortretend, eine 5,6-Epoxidverbindung mit einer Alkinbindung zwischen C7 und C8, welche durch Hydrierung zur Olefinbindung nachgewiesen wurde.5.Das normalerweise nur in Spuren nachweisbare Diatoxanthin erscheint nach Belichtung der Algen in größeren Mengen.6.In den Xanthophyceen — außer Pleurochloris — ist ein stark adsorbiertes Xanthophyll zu finden, für welches Strain et al. den Namen Heteroxanthin vorgeschlagen haben. Hinweise zur Konstitution dieses Xanthophylls werden gegeben.7.Die in geringen Mengen vorkommenden Carotinoide sind bei den Xanthophyceen durchwegs 5,6-Epoxide.8.Die Alge Pleurochloris nimmt eine Sonderstellung innerhalb der Xanthophyceen ein. Sie besitzt zwar deren charakteristisches Pigment — den Vaucheriaxanthinester — und nur Chlorophyll a, hat aber sonst die Pigmente der Grünalgen, jedoch nicht deren Hauptxanthophyll Lutein.9.Die im Pigmentmuster der Xanthophyceen dominierenden Alkin-Carotinoide Diadinoxanthin und Diatoxanthin zeigen starke lichtinduzierte Mengenänderungen, die im Dunkeln reversibel sind. Dabei wird während der Belichtung der Algen der Epoxidsauerstoff des Diadinoxanthins abgespalten und an seiner Stelle eine Doppelbindung eingezogen (Diatoxanthin). Das entspricht dem 2. Schritt der in Höheren Pflanzen ablaufenden Violaxanthin→Antheraxanthin→Zeaxanthinumwandlung. Die lichtbedingten Mengenänderungen dieser Pigmente werden bei verschiedenen Xanthophyceen bestimmt und verglichen. Der Einfluß der (Photosynthese-)Hemmstoffe o-Phenanthrolin und Salicylaldoxim auf diesen Cyclus wurde untersucht.
123 citations
TL;DR: The soluble fibre in the barley fibre concentrate was apparently not affected by fermentation, while contents and maximum viscosities of the soluble fibreIn oat fibre concentrates decreased after fermentation, however, the molecular weight was apparentlyNot affected.
122 citations
TL;DR: To the best of the authors' knowledge, this is the first report on the use of continuous headspace solvent microextraction coupled with hydrodistillation for investigation of essential oil components.
121 citations
TL;DR: It is proposed that this repression of FaPE1 expression could be involved in textural changes occurring during fruit senescence.
Abstract: Pectin esterases (PE, EC 3.1.1.11) catalyse the demethylation of pectin. As a result of its activity, structural interactions among cell wall components during cell wall turnover and loosening are affected. In plants, PEs are typically encoded by a gene family. This family has been studied in strawberry (Fragaria3ananassa Duch.) in order to investigate the role of distinct PE genes during fruit ripening and senescence. By a combination of a PCR-based library screening and RT-PCR four different strawberry PE cDNAs, termed FaPE1 to FaPE4, have been isolated. Differential expression of each FaPE gene in various organs and during fruit development was revealed by northern blot. FaPE1 is specifically expressed in fruit, showing an increasing expression during the ripening process up to a maximum in the turning stage. Concerning hormone regulation, auxin treatment increased FaPE1 mRNA levels in green fruit, whereas exogenous ethylene decreased FaPE1 mRNA levels in ripe and senescing fruits. It is proposed that this repression of FaPE1 expression could be involved in textural changes occurring during fruit senescence.
121 citations
References
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01 Jan 1963
TL;DR: In this article, a physiologischer Vorgang auf eine enzymatische Wirkung zuruckgefuhrt werden (vgl. S. 301), besteht die folgende Aufgabe darin, Naheres uber die Eigenschaften des beteiligten Enzyms zu ermitteln.
Abstract: Kann ein physiologischer Vorgang auf eine enzymatische Wirkung zuruckgefuhrt werden (vgl. S. 301), so besteht die folgende Aufgabe darin, Naheres uber die Eigenschaften des beteiligten Enzyms zu ermitteln. Hierzu gehoren die Bestimmung der Reaktions- und Substratspezifitat sowie die Ermittlung der Bedingungen, unter denen eine optimale Wirkung des Enzyms gegeben ist. Wesentlich zur Charakterisierung ist ferner die Untersuchung der Stabilitat des Enzyms und dabei insbesondere die Feststellung, ob es sich um ein Ferment handelt, das zur vollen Aktivitat dialysable Cofaktoren benotigt. Falls diese Frage bejaht wird, ist auch die Bestimmung der unerlaslichen Cofaktoren anzuschliesen. Uberdies bietet auch der Nachweis der Lokalisation des Enzyms in der Zelle (oder im Zellverband) eine entscheidende Moglichkeit zur Charakterisierung des Fermentes. Hinzu kommt schlieslich noch die Untersuchung der Wirkung einzelner Inhibitoren1 auf das Enzym, die zu weitgehender Klarung des Reaktionsmechanismus beitragen kann und eine Abgrenzung der Eigenschaften des untersuchten Fermentes gegenuber ahnlichen Enzymen erlaubt.
2 citations
01 Jan 1962
TL;DR: Optical rotation has been found to be one of the most convenient methods of following the denaturation of proteins and rotatory dispersion is capable of providing information on the folding of the polypeptide chain in proteins and the changes accompanying denaturation.
Abstract: Optical rotation has been found to be one of the most convenient methods of following the denaturation of proteins. Generally speaking denaturation can be defined as a process or sequence of processes in which the spatial arrangement of the polypeptide chains within the molecule is changed from that typical of the native protein to a more disordered arrangement (Kauzmann 1959). The terms “configuration”, “conformation” and “state of folding” are widely used for spatial arrangement. It is probably best to follow the suggestion of Blout (1960) and restrict the use of “configuration” to its original sense, i.e. the spatial arrangement around an asymmetric carbon atom, and to use “conformation” for the shape of the molecule in its entirety. The properties discussed in the previous Chapter i.e., viscosity, diffusion, sedimentation, and light scattering — can all furnish information on the overall shape of proteins or other macromolecules and changes in this shape with environment. Thus Doty, Bradbury and Holtzer (1956) were able to show using these methods, together with streaming birefringence, that poly-γ-benzyl-L-glutamate could exist in two conformations, the α-helix and the solvated randomly coiled form, depending on the solvent. The change from α-helix to random coil was accompanied by marked changes in the optical rotatory properties of the polypeptides. It is to be expected that an α-helical structure should contribute to the rotatory power of a polypeptide since helices are asymmetric and not superimposable on their mirror images. The work on polypeptides has shown that rotatory dispersion is capable of providing information on the folding of the polypeptide chain in proteins and the changes accompanying denaturation.
1 citations