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Biomedical subjects

K Apel

Publications and source records attributed to K Apel.

82 records · Page 5Linked to original sources
PubMed1978

The plastid membranes of barley (Hordeum vulgare). Light-induced appearance of mRNA coding for the apoprotein of the light-harvesting chlorophyll a/b protein.

Illumination of dark-grown barley plants induces a massive insertion of the light-harvesting chlorophyll a/b protein into the developing thylakoid membrane. In addition to the onset of chlorophyll synthesis, light induces specifically the appearance of a prominent mRNA species which codes for a polypeptide of Mr 29500. This component was identified as a precursor of the apoprotein of the light-harvesting chlorophyll a/b protein. The precursor has an Mr larger than the authentic protein by approximately 4000. Studies of the chlorophyll-b-less mutant chlorina f2 of barley offer the first clue to the mechanism which controls the light-dependent mRNA formation. The induction of the mRNA coding for the aproprotein of the light-harvesting chlorophyll a/b protein does not seem to be linked directly to the assembly process of the light-harvesting structure and does not require chlorophyll b. It is proposed that light exerts its influence on the mRNA formation by a reaction which is different from the phototransformation of protochlorophyll(ide) to chlorophyll(ide).

Cell Membrane↗
PubMed1977

The light-harvesting chlorophylla a/b.protein complex of the green alga Acetabularia mediterranea. Isolation and characterization of two subunits.

In the green alga Acetabularia mediterranea a light-harvesting chlorophyll a/b.protein complex of 67 000 daltons has been found which contains two polypeptide chains of 21 500 and 23 000 daltons. These two polypeptides were isolated on a preparative scale and were further characterized by several different methods. Both polypeptides proved to be very similar. While their amino acid and sugar compositions as well as their immunochemical properties were almost identical the tryptic peptides and the cyanogen bromide fragments of the two polypeptides revealed minor but significant differences. The 67 000-dalton chlorophyll a/b.protein complex and its two polypeptide components were compared to the light-harvesting chlorophyll a/b.protein of higher plants.

Acetabularia↗
PubMed1976

Light-induced increase in the activity of maize plastid DNA-dependent RNA polymerase.

Illumination of dark-grown maize plants induces a rapid rise in DNA-DEPENDENT RNA polymerase activity in plastids. Within 16 h illumination the enzyme activity is isolated plastids increases 3-4 fold as compared to other dark-grown plants illuminated for only 2 h. This change in activity is unaccompanied by either a quantitative rise in the amount of chloroplast RNA polymerase or qualitative changes in the purified enzyme. It is suggested that other factors may be present which interact either with the enzyme or the DNA template and that these factors are responsible for the light-induced enhancement of the RNA polymerase activity inplastids.

Chlorophyll↗
PubMed1976

Chloroplast membranes of the green alga Acetabularia mediterranea. II. Topography of the chloroplast membrane.

The localization of the chlorophyll-protein complexes inside the thylakoid membrane of Acetabularia mediterranea was determined by fractionating the chloroplast membrane with EDTA and Triton X-100, by using pronase treatment, and by labeling the surface-exposed proteins with 125I. The effects of the various treatments were established by electrophoresis of the solubilized membrane fractions and electron microscopy. After EDTA and pronase treatment, the membrane structure was still intact. Only the two chlorophyll-protein complexes of 67,000 and 152,000 daltons and an additional polypeptides were found in the membrane before the EDTA and pronase treatment. The 125,000 dalton complex seems to be buried inside the lipid layer. The 23,000 dalton subunit of the 67,000 dalton complex is largely exposed to the surface of the EDTA-insoluble membrane and only the chlorophyll-binding subunit of 21,500 daltons is buried inside the lipid layer.

Acetabularia↗
PubMed1975

Chloroplast membranes of the green alga Acetabularia mediterranea. I. Isolation of the photosystem II.

1. In the presence of Triton X-100, chloroplast membranes of the green alga Acetabularia mediterranea were disrupted into two subchloroplast fragments which differed in buoyant density. Each of these fractions had distinct and unique complements of polypeptides, indicating an almost complete separation of the two fragments. 2. One of the two subchloroplast fractions was enriched in chlorophyll b. It exhibited Photosystem II activity, was highly fluorescent and was composed of particles of approx. 50 A diameter. 3. The light-harvesting chlorophyll-protein complex of the Photosystem II-active fraction had a molecular weight of 67 000 and contained two different subunits of 23 000 and 21 500. The molecular ratio of these two subunits was 2:1.

Acetabularia↗
PubMedDate not supplied

A powder made from seeds and shells of a rose-hip subspecies (Rosa canina) reduces symptoms of knee and hip osteoarthritis: a randomized, double-blind, placebo-controlled clinical trial.

OBJECTIVE: The aim of this study was to determine whether a herbal remedy made from a subspecies of rose-hip (Rosa canina) might reduce symptoms of osteoarthritis and consumption of rescue medication in patients suffering from osteoarthritis. METHODS: Ninety-four patients with osteoarthritis of the hip or knee were enrolled in a randomized, placebo-controlled, double-blind crossover trial. Forty-seven patients were given 5 g of the herbal remedy daily for a period of 3 months and the remaining patients were given a similar amount of placebo. The group initially treated with placebo was then changed to rose-hip and vice versa for another 3-month period. Upon inclusion and after 3 weeks and 3 months of each treatment period, pain, stiffness, disability, and global severity of the disease were scored on a Western Ontario and McMaster Universities (WOMAC) questionnaire. After 3 weeks of treatment, patients, if possible, were allowed to reduce their consumption of 'rescue medication'. Data were analysed on the basis of intention to treat. RESULTS: Rose-hip resulted in a significant reduction in WOMAC pain (p<0.014) as compared to placebo, when testing after 3 weeks of treatment. The consumption of 'rescue medication' significantly declined as a result of active treatment (p<0.027). WOMAC disability, stiffness, and global assessment of severity of the disease were not altered by 3 weeks but decreased significantly (p<0.018, p<0.038, and p<0.035, respectively) after 3 months of treatment. CONCLUSION: The data suggest that the present herbal remedy can alleviate symptoms of osteoarthritis and reduce the consumption of 'rescue medication'.

Adult↗