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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01 Jan 1970
TL;DR: In this article, methods for isolation, chromatographic separation, and identification of carotenoids are described, which distinguish the oxygen-functions (hydroxy-, epoxid- and keto-groups) of the carotene molecule.
Abstract: SummaryMethods for isolation, chromatographic separation and identification of carotenoids are described. Chemical reactions are emphasized, which distinguish the oxygen-functions (hydroxy-, epoxid- and keto-groups) of the carotene molecule.
1.With the aid of the very selective thin-layer B, algal carotenoids (including stereoisomeric forms) have been isolated, which have not been separable by chromatography until now.2.Analytical methods for the determination of hydroxy-groups in carotenes as, e.g., formation of esters and ethers and elimination reactions were studied to characterize their specificity, side effects and applicability at micro-scale.The demonstration of allylic secondary OH-groups by their elimination in acidic inert solvents is not specific when tertiary hydroxy-groups are present. The establishment of such allylic secondary OH-groups by formation of ethers in acidic alcohols is difficult, because tertiary hydroxy-groups are eliminated and a furanoid rearrangement of epoxide-groups takes place. Allylic secondary OH-groups can be established, however, beyond question by their oxidation to keto-groups with the aid of the Meerwein-Ponndorf-Verley-Oppenauer reaction.3.To clarify the structure of carotenoid-5,6-epoxides the reduction to the corresponding 5,6-olefine is used. A chemical reduction method modified for small amounts and an enzymatic transformation are described.4.Number and position of keto-groups may be derived from the changed characteristics (e.g. in the absorption spectrum and in the Rf-value) of the carotenoid molecules after reduction of these groups to hydroxy-groups.5.Alkine bonds and allenic structures in carotenoids cause no changes in the absorption spectrum in the visible region and very small changes in the IR-region. Therefore, the difference in Rf-values on thinlayer B plates, is a first important indication for these structures. Pigments with allenic structures can be identified by treatment with LiAlH4 and by transformation to the corresponding pigments with conjugated dien-structure.The alkinic bond (e.g. in the xanthophyll-epoxide diadinoxanthin) may be established by TiCl4-treatment.6.Carotenoids are rearranged in the retro-form by the electrophilic reagent TiCl4. The action of TiCl4 upon different carotenoids has been examined.ZusammenfassungEs werden Methoden zur Isolierung, chromatographischen Trennung und Identifizierung von Carotinoiden beschrieben. Vor allem werden chemische Reaktionen aufgezeigt, welche einen Nachweis der Sauerstoffunktionen (Hydroxyl-, Epoxid- und Ketogruppen) am Carotinmolekül gestatten.
1.Mit Hilfe der sehr selektiven D\:unnschicht B wurde die Isolierung von bisher chromatographisch nicht trennbaren Carotinoiden einschlie\sBlich stereoisomerer Formen aus verschiedenen Algenklassen erm\:oglicht.2.Die Methoden zum Nachweis von Hydroxylgruppen am Carotinmolek\:ul, wie Esterbildung, \:Atherbildung und Eliminierung, werden auf ihre Spezifit\:at, Nebenwirkungen und Anwendbarkeit im Mikroma\sBstab untersucht.Der Nachweis von allylständigen sekundären OH-Gruppen durch ihre Eliminierung in HCl-haltigen inerten Lösungsmitteln ist bei Vorliegen von tertiären Hydroxylgruppen nicht spezifisch. Auch wird der Nachweis von solchen allylständigen sek. OH-Gruppen durch Verätherung in HCl-haltigen Alkoholen erschwert, da hierbei tertiäre Hydroxyle eliminiert werden und furanoide Umlagerungen von Epoxidgruppen stattfinden. — Ein einwandfreier Nachweis von allylständigen sek. OH-Gruppen ist jedoch durch ihre Oxydation zu Ketogruppen mit Hilfe der Meerwein-Ponndorf-Verley-Oppenauer-Reaktion möglich.3.Zur Strukturaufkl\:arung der Carotinoid-5,6-Epoxide wird die Reduktion zum entsprechenden 5,6-Olefin ben\:utzt. F\:ur diese Deepoxydierung werden eine f\:ur geringe Substanzmengen modifizierte chemische Reduktionsmethode und eine enzymatische Umsetzung angegeben.4.Die Bestimmung der Zahl und Stellung von Ketogruppen kann durch die ver\:anderten Eigenschaften (z. B. im Absorptionsspektrum und im Rf-Wert) des Carotinoidmolek\:uls nach der Reduktion dieser Gruppen zu Hydroxylgruppen erfolgen.5.Da Alkinbindungen und Allenstrukturen in Carotinoidmolek\:ulen keine Ver\:anderungen des Absorptionsspektrums im sichtbaren Bereich und nur sehr geringe im IR-Bereich verursachen, ist der auf der D\:unnschicht B erkennbare Rf-Wert-Unterschied ein erster wichtiger Hinweis.Pigmente mit Allenstrukturen können überdies durch LiAlH4-Behandlung in die entsprechenden Pigmente mit konjugierter Dienstruktur umgelagert und so identifiziert werden. Die Alkinbindung (z. B. bei dem Xanthophyll-Epoxid Diadinoxanthin) kann durch TiCl4-Behandlung nachgewiesen werden.6.Durch das elektrophile Reagens TiCl4 werden Carotinoide in die Retro-Form umgelagert. Die Wirkung von TiCl4 auf verschiedene Carotinoide wird untersucht.
45 citations
TL;DR: A procedure allowing the purification of milligram amounts of the exocellular dd-carboxypeptid enzyme-transpeptidase from Streptomyces R61 to protein homogeneity (95% purity) is described.
Abstract: A procedure allowing the purification of milligram amounts of the exocellular dd-carboxypeptidase–transpeptidase from Streptomyces R61 to protein homogeneity (95% purity) is described. The isolated protein has a molecular weight of about 38000 and consists of one polypeptide chain. Its amino acid composition is presented.
45 citations
TL;DR: It is suggested that ethylene in relation to water status and lipid peroxidation and along with other metabolic processes has an important role in induced nodules senescence under salinity.
45 citations
TL;DR: A functional model describing the organization of Cryptophyceae thylakoid membrane is proposed, and many features were comparable in the two PS II fractions, but the photosynthetical activities revealed an opposite repartition of PS II reaction centres and light-harvesting antennae.
45 citations
01 Jan 1964
TL;DR: This chapter deals with components that are involved in the transfer of electrons from reduced pyridine nucleotides to molecular O2 in plant tissues.
Abstract: This chapter deals with components that are involved in the transfer of electrons from reduced pyridine nucleotides to molecular O2 in plant tissues The knowledge in this field is far from complete, and only in limited areas is there any exact enzymological information On the other hand, a good deal of work has been done towards establishing the nature of the physiological respiratory chain, and experiments at this level have provided the background for subsequent chemical investigations The first section of this review deals with the methods commonly used to characterize the intact respiratory chain Following this, the techniques used to study the individual components of this system are considered in detail Plant tissues contain a variety of other enzymes which react with O2 and the possibility that these may participate in alternative respiratory pathways has frequently been considered; these enzymes are discussed in the last section
45 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