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Biomedical subjects

E Wellmann

Publications and source records attributed to E Wellmann.

17 recordsLinked to original sources
PubMed2000

Assay of DNA photolyase activity in spinach leaves in relation to cell compartmentation-evidence for lack of DNA photolyase in chloroplasts.

Spinach cyclobutane pyrimidine dimer (CPD)-specific DNA photolyase was successfully detected in leaf extracts by an assay system for plant photolyase using an improved enzyme-linked immunosorbent assay (ELISA) which was newly introduced by novel horseradish peroxidase (HRP)-linked CPD specific monoclonal antibodies. The assay system includes two main steps: a photorepair reaction of CPD introduced in substrate DNA and measurement of CPD remained after the photorepair by the improved ELISA. When CPD- induced salmon sperm DNA was used as a substrate, high CPD-photolyase activities were observed in the enzyme fraction prepared from whole spinach leaf extracts, but not from chloroplast extracts. This strongly suggests that spinach CPD-specific photolyases are localized in cell compartments other than chloroplasts.

Animals↗
PubMed1998

The cell wall-anchored Streptomyces reticuli avicel-binding protein (AbpS) and its gene.

Streptomyces reticuli produces a 35-kDa cellulose-binding protein (AbpS) which interacts strongly with crystalline forms of cellulose (Avicel, bacterial microcrystalline cellulose, and tunicin cellulose); other polysaccharides are recognized on weakly (chitin and Valonia cellulose) or not at all (xylan, starch, and agar). The protein could be purified to homogeneity due to its affinity to Avicel. After we sequenced internal peptides, the corresponding gene was identified by reverse genetics. In vivo labelling experiments with fluorescein isothiocyanate (FITC), FITC-labelled secondary antibodies, or proteinase K treatment revealed that the anchored AbpS protrudes from the surfaces of the hyphae. When we investigated the hydrophobicity of the deduced AbpS, one putative transmembrane segment was predicted at the C terminus. By analysis of the secondary structure, a large centrally located alpha-helix which has weak homology to the tropomyosin protein family was found. Physiological studies showed that AbpS is synthesized during the late logarithmic phase, independently of the carbon source.

Amino Acid Sequence↗
PubMed1987

Chlorogenic acid biosynthesis: characterization of a light-induced microsomal 5-O-(4-coumaroyl)-D-quinate/shikimate 3'-hydroxylase from carrot (Daucus carota L.) cell suspension cultures.

Microsomal preparations from carrot (Daucus carota L.) cell suspension cultures catalyze the formation of trans-5-O-caffeoyl-D-quinate (chlorogenate) from trans-5-O-(4-coumaroyl)-D-quinate. trans-5-O-(4-Coumaroyl)shikimate is converted to about the same extent to trans-5-O-caffeoylshikimate. trans-4-O-(4-Coumaroyl)-D-quinate, trans-3-O-(4-coumaroyl)-D-quinate, trans-4-coumarate, and cis-5-O-(4-coumaroyl)-D-quinate do not act as substrates. The reaction is strictly dependent on molecular oxygen and on NADPH as reducing cofactor. NADH and ascorbic acid cannot substitute for NADPH. Cytochrome c, Tetcyclacis, and carbon monoxide inhibit the reaction suggesting a cytochrome P-450-dependent mixed-function monooxygenase. Competition experiments as well as induction and inhibition phenomena indicate that there is only one enzyme species which is responsibl for the hydroxylation of the 5-O-(4-coumaric) esters of both D-quinate and shikimate. The activity of this enzyme is greatly increased by in vivo irradiation of the cells with blue/uv light. We conclude that the biosynthesis of the predominant caffeic acid conjugates in carrot cells occurs via the corresponding 4-coumaric acid esters. Thus, in this system, 5-O-(4-coumaroyl)-D-quinate can be seen as the final intermediate in the chlorogenic acid pathway.

Carbon Monoxide↗
PubMed1985

Isoflavonoid Formation as an Indicator of UV Stress in Bean (Phaseolus vulgaris L.) Leaves : The Significance of Photorepair in Assessing Potential Damage by Increased Solar UV-B Radiation.

Induction of the isoflavonoid pigment, coumestrol (3,9-dihydroxy-6H-benzofuro-[3,2-c][1] benzopyran-6-one), in primary leaves of beans (Phaseolus vulgaris L. var Saxa) by ultraviolet (UV) radiation was used as a quantifiable marker for UV damage to a plant system. Coumestrol was induced only by wavelengths below 300 nanometers and its formation could be reversed by treatment with white, but not red light after the UV irradiation period. Formation of coumestrol by UV could also be prevented over a period of 14 hours by simultaneous irradiation with blue light provided that the blue fluence rate was high enough. The results suggest that coumestrol formation is mediated via UV-induced pyrimidine dimer formation in the plant DNA and the photorepair properties of blue light are discussed with respect to possible increases in solar UV due to stratospheric ozone depletion.

Journal Article↗
PubMed1984

UV-B Inhibition of Phytochrome-Mediated Anthocyanin Formation in Sinapis alba L. Cotyledons : Action Spectrum and the Role of Photoreactivation.

An action spectrum was measured for ultraviolet (UV) radiation-induced damage to (inhibition of) phytochrome-induced anthocyanin formation in cotyledons of 40-hour-old Sinapis alba L. seedlings. The action spectrum showed maximum effectiveness in the 260 to 280 nanometer waveband with little effect above 295 nanometers. The damaging effect of UV could be photorepaired by subsequent exposure to sunlight or to long wavelength (360 nanometers) UV radiation. Because this form of damage is subject to photorepair (photoreactivation), it is probably due to the formation of pyrimidine dimers, and the results suggest that it would not be ecologically relevant even if there was an increase in solar UV due to a decrease in stratospheric ozone levels of about 30%. If a dark period of more than 1 hour is interspersed between the phytochrome induction and the UV irradiation, the inhibition of the phytochrome induction gradually decreases with increasing dark period.

Journal Article↗
PubMed1976

Coordinated induction and subsequent activity changes of two groups of metabolically interrelated enzymes. Light-induced synthesis of flavonoid glycosides in cell suspension cultures of Petroselinum hortense.

The enzymes of the flavonoid glycoside pathway were specifically induced upon irradiation of a 10-day-old, dark-grown cell suspension culture of Petroselinum hortense Hoffm. with ultraviolet light. The curves for the activity changes of a first sequence of three enzymes (group I) revealed only small, but significant, differences. Sharp peaks in these enzyme activities were observed at about 17, 22, and 23 h after the onset of the irradiation. The apparent half-lives during the subsequent periods of decline ranged, in the same order, from about 10 to 15 and 17 h. No significant differences were found for the lag periods preceding the increases in the three enzyme activities. The possibility is discussed that the slight differences in the patterns of the light-induced activity changes are mainly due to different rates of degradation of the enzymes, suggesting an otherwise largely interpendent regulation. The patterns of the activity changes of four enzymes of the second sequence (group II) differed greatly from those observed for group I, but were again similar to one another. Thus, the two groups of enzymes appear to be regulated differently, despite their concomitant induction. A sigmoidal curve for the accumulation of the flavonoid glycosides was obtained upon the induction of the enzymes. This curve corresponded closely to that derived by integration of the curve for the activity changes of the first enzyme of group I, phenylalanine ammonia-lyase. It is concluded that this enzyme might be rate-limiting for the entire pathway.

Acyltransferases↗
PubMed1975

Phytochrome-mediated de Novo Synthesis of Phenylalanine Ammonia-Lyase in Cell Suspension Cultures of Parsley.

After a preirradiation with ultraviolet light, phenylalanine ammonia-lyase activity in cell suspension cultures of parsley (Petroselinum hortense Hoff.) is controlled by phytochrome (red/far red photoreversibility). Isopycnic CsCl density gradient centrifugation, after labeling with (15)N (90 atom%) under inductive and noninductive conditions, was used to investigate the mode of action of phytochrome in this response. After a 5hour labeling period, a buoyant density shift of 0.009 kg.l(-1) (0.7%) without band-broadening (indicating close to maximal labeling of the enzyme), was observed in irradiated cells. In dark-grown controls, the density shift was 0.004 kg.l(-1) (0.3%), accompanied by significant band-broadening, indicating turnover of about half of the enzyme pool during 5 hours. These results are taken as evidence that phytochrome controls de novo synthesis of this enzyme over a background of basal turnover.

Journal Article↗
PubMed1975

[Effect of radiation changes in the spectrum UV on plant organisms].

The synthesis of UV absorbing pigments (flavonoids), induced by UV (lambdamax less than 300 nm) with linear dose dependency, which we have recently observed in seedlings of the Umbelliferae, is described. This may provide a protective mechanism against an excess of solar UV radiation. The physiological importance of UV for the plant is discussed from the point of view of radiation damage and the plant's resistance to it.

Dose-Response Relationship, Radiation↗