M. Mäder
Heidelberg University
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Featured researches published by M. Mäder.
Planta | 1980
M. Mäder; Jutta Ungemach; Patrick Schloß
Three peroxidase isoenzyme-groups found in cell walls of tobacco were tested for their capacity to form H2O2. Isoenzyme-group GI, located only in cell walls (GII and GIII are also found in protoplasts) showed the highest Kapp-value for H2O2-formation. The lowest Kapp-value, i.e., maximal H2O2-formation was received for group GIII which is ionically bound to the cell wall. As shown before, GI yields maximal polymerization rates for coniferyl- and p-coumarylalcohol. These facts indicate that each of the peroxidase isoenzyme groups of the cell wall is involved with different catalytic functions within the same pathways of H2O2-formation and succeeding lignification. H2O2-formation catalyzed by all 3 groups was increased by very low concentrations of Mn2+-ions. The required amount of Mn2+ leading to maximal stimulation was in each case dependent on the basic rate of H2O2-formation. Maximal stimulation of H2O2-formation by phenolic compounds was achieved by coniferylalcohol at a concentration of 10-4M for all groups. Stimulation by p-coumaryl-and by sinapylalcohol was not as significant.
Planta | 1975
M. Mäder; Yves Meyer; Martin Bopp
SummaryUpon disk-electrophoresis with guaiacol as a substrate the peroxidase-isoenzymes of Nicotiana tabacum (L.) were localized on the gels in two anodic and two cathodic groups. By preparation of protoplasts and isolation of cell walls it was possible to show that only cathodic enzymes are located in the protoplasts in measurable amounts, whereas all the isoenzymes, anodic and cathodic, can be found associated with cell walls. The different groups of isoenzymes are bound to the cell wall in different ways as evidenced by differences in their extration. It seems possible that different biological functions are associated with the different groups of isoenzymes.The isoenzyme patterns of different organs and tissues of tobacco show qualitative differences only in the anodic (i.e. wall located) isoenzymes. It is suggested that the ontogenetic change in peroxidase-patterns is direct evidence of biochemical differences in the cell walls of the different tissues and organs.
Planta | 1987
Patrick Schloß; C. Walter; M. Mäder
Vacuoles of tobacco mesophyll and of suspension-cultured cells were isolated in order to study the localization of peroxidase isoenzymes. Only basic peroxidases were detectable by electrophoretic separation of the vacuolar sap. Some of the basic peroxidases have formerly been described as an ionically bound cell-wall fraction. This fraction, however, was found to be an artifact produced by incomplete cell breakage. Reinvestigation of isolated cell walls confirmed that mainly acidic peroxidases are localized in the cell walls where they move freely or are bound. As a consequence of former and present results we think it probable that all of the peroxidase isoenzymes are secretory proteins because they have to be transported from the sites of synthesis in the cytoplasm to the sites of function, the extracytoplasmic spaces, cell wall (acidic peroxidases), and vacuole (basic peroxidases).
Zeitschrift für Pflanzenphysiologie | 1977
M. Mäder; A. Nessel; Martin Bopp
Summary The present communication describes the determination of apparent Michaelis-constants of three peroxidase-isoenzyme-groups for several artificial (chemicals which are active in the peroxidase catalysed reaction) and natural substrates (compounds which are found in plants and which possibly act as electrondonors for H 2 O 2 -reduction by peroxidases in vivo ). G I (cell wall located group) has lowest Michaelis-constants for artificial, G III (protoplast located group) for natural substrates. Scopoletin is no substrate for G III , but for G I particularly and to some extent for G II . Maximal oxidation rates of different flavan-derivatives are highest for G I or G II and lowest for G III . The in vitro polymerisation of cumaryland coniferylalcohol to lignin-like-substances is catalysed by G I and G II to a substantial rate but hardly by G III . All the isoenzyme groups exhibit indole-3-acetic oxidase but no phenol-oxidase-activity. The results are discussed in connection with several hypotheses of peroxidase-function and with the localisation of peroxidase-isoenzyme-groups in tissues of tobacco.
Planta | 1976
M. Mäder
SummaryBy vacuum infiltration of intercellular spaces of tobacco tissues it is possible to extract substances from cell walls which move freely in the walls. The peroxidases (E.C. 1.11.1.7) contained in these extracts are predominantly isoenzymes of GI (fast migrating anodic group) as was shown by discelektrophoresis of the extracts. As has been demonstrated previously GI is not present in the protoplast; therefore GI is the typical cell wall fraction of tobacco peroxidases. Different tissues of tobacco always differ in the isoenzyme pattern of GI. This pattern also changes during tissue development. We can therefore say that there exists an enzymatic differentiation of plant cell walls during development. As GI is not bound to the walls, it always appears in high amounts in crude extracts of plant material. Therefore GI is always called the soluble cytoplasmic fraction, but our investigations clearly demonstrate that GI is localized in cell walls only. Beside GI there are much smaller amounts of GIII (slow migrating cathodic group) and if present in the tissue GII (slow migrating anodic group) detectable in the infiltration fluids of intracellular spaces. GIII and GII are localized mainly in the protoplast. But they are also bound to the walls, ionically in the case of GIII and covalently in the case of GII.By vacuum infiltration of intercellular spaces of tobacco tissues it is possible to extract substances from cell walls which move freely in the walls. The peroxidases (E.C. 1.11.1.7) contained in these extracts are predominantly isoenzymes of GI (fast migrating anodic group) as was shown by discelektrophoresis of the extracts. As has been demonstrated previously GI is not present in the protoplast; therefore GI is the typical cell wall fraction of tobacco peroxidases. Different tissues of tobacco always differ in the isoenzyme pattern of GI. This pattern also changes during tissue development. We can therefore say that there exists an enzymatic differentiation of plant cell walls during development. As GI is not bound to the walls, it always appears in high amounts in crude extracts of plant material. Therefore GI is always called the soluble cytoplasmic fraction, but our investigations clearly demonstrate that GI is localized in cell walls only. Beside GI there are much smaller amounts of GIII (slow migrating cathodic group) and if present in the tissue GII (slow migrating anodic group) detectable in the infiltration fluids of intracellular spaces. GIII and GII are localized mainly in the protoplast. But they are also bound to the walls, ionically in the case of GIII and covalently in the case of GII.
Planta | 1986
M. Mäder; C. Walter
De-novo synthesis of acid and basic peroxidases has been studied in cell suspension cultures of tobacco by incorporation of 3H- and 14C-amino acids. Incorporation rates were found to be high for acid peroxidases and low for basic peroxidases. Synthesis of all peroxidases was inhibited by cycloheximide and actinomycin D. Subculturing of the cells increased the rates of radioactive amino-acid incorporation into all peroxidases within the first 24 h. This rise in peroxidase synthesis was correlated with the age of the transferred cells. The older the cells were the more pronounced was the effect. During the culture cycle the high rates of peroxidase synthesis at the second day dropped back to initial values. Peroxidase synthesis was thus inversely related to peroxidase accumulation which was very low at the beginning and increased continuously. By pulse-chase experiments it has been shown that newly synthesized acid peroxidases accumulated in the medium. This process was inhibited by monensin. Only the acid peroxidases were secreted into the cell wall and from there released. The basic peroxidases were not detectable in the medium.
Planta | 1975
M. Mäder; P. Münch; Martin Bopp
Peroxidase activity and isoenzyme pattern were studied during dedifferentiation of tobacco stem-sections leading to callus formation and during redifferentiation of tobacco callus leading to formation of shoots. These processes are both accompanied by an increase in total peroxidase activity and by characteristic changes in isoenzyme pattern. The isoenzyme pattern of tobacco callus differs from that of tobacco stem-tissue. The plantlets differentiated from the callus show the same pattern as seedlings do.During the differentiation process, before any buds are visible, the callus shows a peroxidase pattern that is determined by a reduction of fast-migrating anodic isoenzymes and by an increase of activity in all the other peroxidase isoenzymes. The formation of this pattern is independent of the growth regulators responsible for the differentiation: only the kind of differentiation itself determines the pattern.By artificial inhibition of callus growth it is possible to induce an isoenzyme pattern very similar to that of differentiation; the fast-migrating anodic enzymes are reduced in activity but the others are not increased as they are during differentiation. Therefore the question arises whether there are two independent processes taking place in differentiating callus. The one process, inhibition of growth in the cells that do not differentiate, is accompanied by a reduction of fast-migrating anodic isoenzymes. The other process, formation of meristemoids in the callus, is accompanied by a sharp rise in peroxidase activity of the other anodic and cathodic isoenzymes.SummaryPeroxidase activity and isoenzyme pattern were studied during dedifferentiation of tobacco stem-sections leading to callus formation and during redifferentiation of tobacco callus leading to formation of shoots. These processes are both accompanied by an increase in total peroxidase activity and by characteristic changes in isoenzyme pattern. The isoenzyme pattern of tobacco callus differs from that of tobacco stem-tissue. The plantlets differentiated from the callus show the same pattern as seedlings do.During the differentiation process, before any buds are visible, the callus shows a peroxidase pattern that is determined by a reduction of fast-migrating anodic isoenzymes and by an increase of activity in all the other peroxidase isoenzymes. The formation of this pattern is independent of the growth regulators responsible for the differentiation: only the kind of differentiation itself determines the pattern.By artificial inhibition of callus growth it is possible to induce an isoenzyme pattern very similar to that of differentiation; the fast-migrating anodic enzymes are reduced in activity but the others are not increased as they are during differentiation. Therefore the question arises whether there are two independent processes taking place in differentiating callus. The one process, inhibition of growth in the cells that do not differentiate, is accompanied by a reduction of fast-migrating anodic isoenzymes. The other process, formation of meristemoids in the callus, is accompanied by a sharp rise in peroxidase activity of the other anodic and cathodic isoenzymes.
Zeitschrift für Pflanzenphysiologie | 1981
Frauke Rohwer; M. Mäder
Summary Activity of ethylene formation from 1-aminocyclopropane-1-carboxylic acid (ACC) was compared to peroxidase (POD) activity in crude extracts of etiolated pea shoots ( Pisum sativum L.) as well as in Sephadex and Concanavalin A-Sepharose (ConA) fractions of these extracts. In crude extracts the stability of POD activity was higher than that of ethylene formation. Mercaptoethanol and sodiumazide inhibited both activities, but other inhibitors of ethylene formation (hydroxylammoniumchloride, catalase, EDTA, KCN, CuSO 4 , CoCl 2 ) had a weak or no effect at all on POD activity. High-molecular weight fractions (FI) from Sephadex of pea crude extracts formed ethylene from ACC and exhibited POD activity. By mixing high molecular weight fractions with low molecular weight fractions from the Sephadex column ethylene formation was stimulated. A similar effect could be reached by substituting FI fractions with horse radish peroxidase (HRP), but ethylene production was very low. After ConA fractionation the highest ethylene formation was found to be in the POD containing eluate, but in addition we found ethylene formation in effluent fractions which showed no POD activity. Mn 2+ otherwise has a stimulating effect on ethylene production from Sephadex fractions as well as from HRP but not on the crude extract. It appears that peroxidase itself does not play a major role in decarboxylation or ring cleavage of ACC, but that it might be involved in a more complex way by providing radicals, H 2 O 2 or otherwise unknown factors.
Plant Science Letters | 1979
M. Mäder; Patrick Schloss
Abstract Isolation of cell wall-bound malate dyhydrogenase (MDH, EC 1.1.1.37) from tobacco was obtained by treating purified cell walls with pectinase and hemicellulase. By electrophoretic separation it was demonstrated that the wall-bound isoenzymes of MDH are different from the cellular ones.
Planta | 1976
M. Mäder; Yves Meyer; Martin Bopp
SummaryMesophyll-protoplasts of tobacco show increasing peroxidase-activity immediately after isolation. This is due to an enhancement of activity of the constitutive isoenzymes of GIII (=slow migrating cathodic group) and to a new formation of GII-isoenzymes (=slow migrating anodic group). (GII is not present in intact leaves.) As both processes are inhibited by actinomycin and actidion it is assumed that there is a new synthesis of peroxidase enzymes —The peroxidase reaction is independent of the further development of the protoplasts, as was evidenced by culturing protoplasts in different media which regulate the development of the protoplasts. Peroxidase reaction is always the same whether or not there is cell-wall synthesis and cell division. This leads to the conclusion that peroxidases in this case have no relation to synthesis of primary cell-walls. On the other hand they could be related to the dedifferentiation processes that always take place in isolated protoplasts.In the protoplasts GII is localized in the cytoplasma as GIII is, because GII appears before cell walls are synthesised and there is no lack of GII isoenzymes when protoplasts are remazerated after having formed new cell walls.GI (fast migrating anodic group), which is not detectable in isolated protoplasts, appears again after small calluses have developed out of protoplasts. Therefore as far as function is concerned GI is quite different from GII and GIII. The results confirm the hypothesis that GI is localized in intercellular spaces only. It is discussed whether all of the isoenzymes of peroxidase detectable in crude extracts are cytoplasmic ones.Mesophyll-protoplasts of tobacco show increasing peroxidase-activity immediately after isolation. This is due to an enhancement of activity of the constitutive isoenzymes of GIII (=slow migrating cathodic group) and to a new formation of GII-isoenzymes (=slow migrating anodic group). (GII is not present in intact leaves.) As both processes are inhibited by actinomycin and actidion it is assumed that there is a new synthesis of peroxidase enzymes -The peroxidase reaction is independent of the further development of the protoplasts, as was evidenced by culturing protoplasts in different media which regulate the development of the protoplasts. Peroxidase reaction is always the same whether or not there is cell-wall synthesis and cell division. This leads to the conclusion that peroxidases in this case have no relation to synthesis of primary cell-walls. On the other hand they could be related to the dedifferentiation processes that always take place in isolated protoplasts.In the protoplasts GII is localized in the cytoplasma as GIII is, because GII appears before cell walls are synthesised and there is no lack of GII isoenzymes when protoplasts are remazerated after having formed new cell walls.GI (fast migrating anodic group), which is not detectable in isolated protoplasts, appears again after small calluses have developed out of protoplasts. Therefore as far as function is concerned GI is quite different from GII and GIII. The results confirm the hypothesis that GI is localized in intercellular spaces only. It is discussed whether all of the isoenzymes of peroxidase detectable in crude extracts are cytoplasmic ones.