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: The results suggest that most, if not all, the nitrite reductase and acetolactate synthetase activity of the cell is in the plastids, and some evidence was obtained for low levels of glutamate dehydrogenase activity in chloroplasts.
Abstract: Density gradient separation of plastids from leaf and root tissue was carried out The distribution in the gradients of the activity of the following enzymes was determined: nitrite reductase, glutamine synthetase, acetolactate synthetase, aspartate aminotransferase, catalase, cytochrome oxidase, and triosephosphate isomerase The distribution of chlorophyll was followed in gradients from leaf tissue The presence of plastids that have retained their stroma enzymes was denoted by a peak of triosephosphate isomerase activity Coincidental with this peak were bands of nitrite reductase, acetolactate synthetase, glutamine synthetase, and aspartate aminotransferase activity The results suggest that most, if not all, the nitrite reductase and acetolactate synthetase activity of the cell is in the plastids The plastids were found to contain only part of the total glutamine synthetase, aspartate aminotransferase, and triosephosphate dehydrogenase activity in the cell Some evidence was obtained for low levels of glutamate dehydrogenase activity in chloroplasts
203 citations
TL;DR: Galactomannans of Gleditsia triacanthos, Caesalpinia pulcherrima and Adenanthera pavonina were structurally and thermally characterized in this article.
202 citations
TL;DR: It is shown that Pectic oligosaccharides (POS) can have a beneficial effect on the fecal microflora; however, a classical prebiotic effect was not found.
Abstract: Fermentation properties of oligosaccharides derived from orange peel pectin were assessed in mixed fecal bacterial culture. The orange peel oligosaccharide fraction contained glucose in addition to rhamnogalacturonan and xylogalacturonan pectic oligosaccharides. Twenty-four-hour, temperature- and pH-controlled, stirred anaerobic fecal batch cultures were used to determine the effects that oligosaccharides derived from orange products had on the composition of the fecal microbiota. The effects were measured through fluorescent in situ hybridization to determine changes in bacterial populations, fermentation end products were analyzed by high-performance liquid chromatography to assess short-chain fatty acid concentrations, and subsequently, a prebiotic index (PI) was determined. Pectic oligosaccharides (POS) were able to increase the bifidobacterial and Eubacterium rectale numbers, albeit resulting in a lower prebiotic index than that from fructo-oligosaccharide metabolism. Orange albedo maintained the growth of most bacterial populations and gave a PI similar to that of soluble starch. Fermentation of POS resulted in an increase in the Eubacterium rectale numbers and concomitantly increased butyrate production. In conclusion, this study has shown that POS can have a beneficial effect on the fecal microflora; however, a classical prebiotic effect was not found. An increase in the Eubacterium rectale population was found, and butyrate levels increased, which is of potential benefit to the host.
201 citations
TL;DR: The hypothesis that the glucose conjugate is a long-distance transport form of ABA is supported and the first biochemical and physiological characterization of the extracellular glucosidase activity in barley is given.
Abstract: Abscisic acid conjugate concentrations increased in barley xylem sap under salinity, whereas it remained at a low level in the intercellular washing fluid (IWF) of barley primary leaves (Hordeum vulgare cv. Gerbel). Here it is shown that IWF contains beta-glucosidase activity which releases abscisic acid (ABA) from the physiologically inactive ABA-glucose conjugate pool in the leaf apoplast, The following data support this conclusion and give the first biochemical and physiological characterization of the extracellular glucosidase activity in barley. Free ABA was released by the incubation of ABA glucose ester with IWF. The product exhibited the retention time of authentic ABA upon separation by thin layer chromatography and was identified by ABA-ELISA. p-Nitrophenol-beta-D-glucopyranoside (pNPG) was used as the substrate for beta-glucosidases. The K-M (pNPG) was 1.8 mmol l(-1). The activity was affected by ABA glucopyranoside in a competitive type of inhibition with a K-I of 400 mu mol l(-1). Various hormone conjugates were compared with respect to their inhibitory effect on beta-glucosidase activity. Inhibition was highest for the ABA glucopyranoside and the zeatin riboside, but insignificant for ABA methyl ester and zeatin-9-beta-D-glucoside. The specific activity of the beta-glucosidase was 16-fold greater in IWF as compared to crude leaf extracts confirming its extracellular compartmentation. The activity of beta-glucosidase was strongly increased after growth in hydroponic medium supplemented with NaCl. The data support the hypothesis that the glucose conjugate is a long-distance transport form of ABA.
200 citations
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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