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: In this article, the reaction between (+)-catechin and glyoxylic acid was investigated as a model system of color changes usually observed during conservation and ageing of fruit-derived foods.
52 citations
01 Jan 2005
TL;DR: In this paper, gas chromatography and GC/MS methods were used to detect volatile components of three home-made natural old plum brandy samples and one sample of industrially-produced brandy.
Abstract: Summary Gas chromatography and GC/MS methods were used to detect volatile components of three home-made natural old plum brandy samples and one sample of industrially-produced plum brandy. Gas chromatography and gas chromatography-mass spectrometric analysis of this extracts led to the identification of 99 components, including 46 esters, 7 hydrocarbons (alkanes and alkenes), 3 aldehydes, 9 alcohols, 1 lactone, 1 ketone, 8 acetals, 14 terpenes, 8 acids and 2 phenols. Ethyl esters of C8–C18 acids were the most abundant in all samples. In addition, the content of methanol, ethanol and higher alcohols C3–C5 was determined.
52 citations
01 Jan 1980
TL;DR: This chapter presents the distinction between two main types of nitrate reductases on a phylogenetic basis, namely: the eukaryotic type and one (or possibly more) prokaryotic types.
Abstract: Publisher Summary This chapter reviews the structure and mechanism of nitrate reductases and presents the distinction between two main types of nitrate reductases on a phylogenetic basis, namely: the eukaryotic type and one (or possibly more) prokaryotic types. The most critical and least understood aspects of the biochemistry of nitrate reduction are the electronic events associated with the production of nitrite from nitrate at the molybdenum center. The eukaryotic forms of nitrate reductases are reported to lie in the molecular weight range between 160,000 and 500,000; although the elliptical shape of the enzyme, as shown by its anomalous behavior on sucrose density centrifugation and gel filtration, requires that more than one method of molecular weight estimation be used to determine the true value. The presence of subunits is characteristic of all the eukaryotic forms of the enzyme studied to date but their sizes and probable numbers differ quite widely. For the prokaryotic, the molecular weight of the purified terminal moieties obtained from prokaryotic sources range from 69,000 to 880,000. Subunit compositions for these are complex and not consistent in terms either of methods of dissociation or of different preparations from separate laboratories.
52 citations
01 Jan 1958
TL;DR: The present review is intended to cover the major advances that have taken place since the appearance of the author’s monograph in 1951, but with the publication of the recent excellent review by Wigglesworth the treatment has been modified to make the present review supplementary in so far as possible.
Abstract: The present review is intended to cover the major advances that have taken place since the appearance of the author’s monograph in 1951. But with the publication of the recent excellent review by Wigglesworth [170], the treatment has been modified to make the present review supplementary in so far as possible. Frequent reference will be made to both of the above.
52 citations
TL;DR: Examination of pigments of the endosymbiotic algae in Cyanophora paradoxa and Glaucocystis nostochinearum and two Rhodophyceae and Porphyridium aerugineum and Asterocytis ramosa has shown them to contain chlorophyll a, β-carotene, zeaxanthin, C-phycocyanin and small amounts of allophycOCyanin.
Abstract: The pigments of the endosymbiotic algae in Cyanophora paradoxa (colorless cryptomonad) and Glaucocystis nostochinearum (colorless Chlorophyceae) and two Rhodophyceae, Porphyridium aerugineum and Asterocytis ramosa have been examined. Both endosymbionts contain chlorophyll a, β-carotene, zeaxanthin, C-phycocyanin and small amounts of allophycocyanin. Porphyridium has been shown to contain chlorophyll a, β-carotene and zeaxanthin, as does Asterocytis ramosa. The biliproteins of Porphyridium have not been examined, but evidence is presented to suggest that Asterocytis ramosa may contain R-phycocyanin and possibly C-phycocyanin. The taxonomic implications of these results have been discussed, especially with regard to cyanome symbionts and their evolution from and classification with the Cyanophyceae.
52 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