Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00080 (Leaf)
 21,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thylakoids of vegetative cells of the filamentous cyanobacterium, Anabaena cylindrica, are capable of oxygen-evolving photosynthesis and contain both Photosystems I and II (PSI and PSII). The heterocysts, cells specialized for nitrogen fixation, do not produce oxygen and lack Photosystem II activity, the major accessory pigments, and perhaps the chlorophyll a associated with PSII. Freeze-fracture replicas of vegetative cells and of heterocysts reveal differences in the structure of the thylakoids. A histogram of particle sizes on the exoplasmic fracture face (E-face, EF) of vegetative cell thylakoids has two major peaks, at 75 and 100 A. The corresponding histogram for heterocyst thylakoids lacks the 100 A size class, but has a very large peak at about 55 A with a shoulder at 75 A. Histograms of protoplasmic fracture face (P-face, PF) particle diameters show single broad peaks, the mean diameter being 71 A for vegetative cells and 64 A for heterocysts. The thylakoids of both cell types have about 5600 particles/micrometers2 on the P-face. On the E-face, the density drops from 939 particles/micrometers2 on vegetative cell thylakoids to 715 particles/micrometers2 on heterocyst thylakoids. The data suggest that the 100 A E-face particle of vegetative cell thylakoids is a PSII complex. The 55 A EF particle of heterocysts may be part of the nitrogenase complex or a remnant of the PSII complex. The role of the 75 A EF particle is unknown. Other functions localized on cyanobacterial thylakoids, such as respiration and hydrogenase activity, must be considered when interpreting the structure of these complex thylakoids.
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PMID:Changes in thylakoid structure associated with the differentiation of heterocysts in the cyanobacterium, Anabaena cylindrica. 11 Mar 42

The successful cultivation of a variety of haemoflagellates in three different liquid media is reported. These media include medium 199, Grace's insect tissue-culture medium and Schneider's drosophila medium, each in combination with 30% (v/v) foetal calf serum. These media were used to cultivate Old and New World species of visceral and cutaneous human Leishmania, as well as Leishmania species isolated from sandflies, rodents, and reptiles. Four strains of Trypanosoma cruzi, an isolate of T. R-angeli and and an isolate of T. lewisi have also been cultivated in these media. One or more of these media have been used to cultivate 121 strains of haemoflagellates, including at least 14 different species (11 Leishmania and 3 Trypanosoma) and many geographic isolates or strains. The Leishmania include L. braziliensis, L. peruviana, L. mexicana, L. tropica, L. donovani, L. chagasi, L. enriettii, L. hertigi, L. hoogstraali, L. adleri, and L. agamae. Using the Schneider's based medium, we have obtained primary isolates of both cutaneous and visceral Leishmania of man and of experimentally infected laboratory rodents and canines. Freeze-dried preparations of the Schneider's based medium that were reconsituted with distilled water after 24 months of storage at ambient temperature have proven to be suitable cultivation media. This feature makes the media valuable field tools. The various species of human Leishmania cultivated in these media have in our experience demonstrated no differences in growth rate, viability after liquid nitrogen preservation, or infectivity for laboratory animals and tissue-culture cells compared with promastigotes derived from blood-agar cultivation.
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PMID:Haemoflagellates: commercially available liquid media for rapid cultivation. 35 27

The fine structure of the regular arrays of subunits seen on both plasmalemma fracture faces in resting and starved Saccharomyces cerevisiae (baker's yeast) has been compared using different freeze-fracture replication methods. Freeze-cleaving was carried out at 173 degrees, 133 degrees, and 108 degrees K under a vacuum of 2 X 10(-7) torr (2.6 X 10(- 7)mbar) or under liquid nitrogen at atmosphereic pressure. Independent of the preparation conditions (fracturing temperature, and whether cleaved under vacuum or liquid nitrogen), resting and starved yeast show a significant difference in the morphology of the subunits forming the regular arrays. The regularly arranged particles of the P face of the plasmalemma of starved yeast have a clear craterlike structure which has previously been reported to be demonstrated only by freeze-etching at very low temperatures in ultrahigh vacuum. A complementary structure is seen on the plasmalemma E face. Prolonged exposures of fracture faces under the protection of liquid nitrogen-cooled shrouds have shown that, because of the consequent drastic reduction of condensable gases in the specimen area, no detectable condensation contamination of exposed fracture faces occurs within 15 min at a specimen temperature of 108 degrees K. This shows that a complicated ultrahigh vacuum technology is not required for high resolution freeze- etching.
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PMID:Freeze-fracturing in normal vacuum reveals ringlike yeast plasmalemma structures. 35 75

Ring, trophozoite, and schizont stages of Plasmodium knowlesi were cooled in dimethyl sulfoxide either by direct immersion in liquid nitrogen or by a two-step method in which the cells were held at temperatures slightly below 0 degrees C for different lengths of time before they were cooled to -196 degrees C. After the direct plunge treatment, thawed trophozoites and schizonts were found to be extensively damaged. Their survival was markedly increased by holding them at -31 degrees C for 30 min before plunging them into liquid nitrogen. Freeze-substitution showed that cells cooled by the two-step procedure were grossly shrunken and had relatively few intracellular ice cavities. Large amounts of ice formed in trophozoites and schizonts preserved by direct immersion in liquid nitrogen. The two-step protocols investigated did not improve the survival of ring-stage parasites, 25-50% of which survived rapid cooling to -196 degrees C. Infected cell agglutination tests were carried out with frozen and thawed schizonts. Variant specificity was demonstrated with cells that had been plunged directly to -196 degrees C, but cells cooled by the two-step method tended to agglutinate spontaneously.
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PMID:Preservation of intraerythrocytic forms of malarial parasites by one-step and two-step cooling procedures. 41 5

The induction of nitrogenase (C2H2) activity in asymbiotically cultured Rhizobium sp. 32H1 was found to be associated with morphological changes in the cells which were more pronounced than those seen in bacteroids. Polyphosphate granules were found in both bacteroids and cultured cells, but poly-beta-hydroxybutyrate vesicles were almost absent in bacteroids but were present in cultured cells. Freeze-etching techniques revealed no differences between the asymbiotically cultured nitrogen-fixing forms and bacteroids in that both the cell wall and cytoplasmic membrane cleavage planes were normal for gram-negative bacteria.
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PMID:Nitrogen fixation by Rhizobium sp. 32H1. A morphological and ultrastructural comparison of asymbiotic and symbiotic nitrogen-fixing forms. 45 50

Most data on the nutrient composition of shell eggs were obtained before 1950. Since then, management systems for egg production and analytical methods for many components have changed. Freeze-dried whole egg, yolk and white samples were prepared from eggs obtained from a single source of 15 month old White Leghorns. The sample were packaged under nitrogen and held at -20 degrees C. until analyzed. Conversion factors are included for expressing the amount of each component on a per egg as well as a per 100 g. edible liquid basis. This re-evaluation of nutrient data included total solids, lipid, protein, cholesterol, ash, calories, amino acids, fatty acids, vitamins and minerals.
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PMID:A nutrient re-evaluation of shell eggs. 56 14

The growth rates of young chicks were varied from 0 to 10% per day by manipulation of the adequacy of the amino acid and energy supply. The rates of protein synthesis in the white breast (pectoralis thoracica) muscle and the dark leg (gastrocnemius and peronaeus longus) muscles were estimated by feeding l-[U-(14)C]tyrosine in amino acid/agar-gel diets (;dietary infusion'). This treatment rapidly and consistently produced an isotopic equilibrium in the expired CO(2) and in the free tyrosine of plasma and the muscles. Wholebody protein synthesis in 2-week-old chicks was estimated from the tyrosine flux and was 6.4g/day per 100g body wt. In 1-week-old chicks the rate of protein synthesis was more rapid in the breast muscles than in the leg muscles, but decreased until the rates were similar in 2-week-old birds. Synthesis was also more rapid in fast-growing Rock Cornish broilers than in medium-slow-growing New HampshirexSingle Comb White Leghorn chicks. No or barely significant decrease in the high rates of protein synthesis, in the protein/RNA ratio and in the activity of RNA for protein synthesis occurred in non- or slow-growing chicks fed on diets deficient in lysine, total nitrogen or energy. Thus the machinery of protein synthesis in the young chick seems to be relatively insensitive to dietary manipulation. In the leg muscles, there was a small but significant correlation between the fractional rate of growth and protein synthesis. A decrease in the fractional rate of degradation, however, appeared to account for much of the accumulation of muscle protein in rapidly growing birds. In addition, the rapid accumulation of breast-muscle protein in rapidly growing chicks appeared to be achieved almost entirely by a marked decrease in the fractional rate of degradation.
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PMID:Growth and muscle protein turnover in the chick. 74 59

A revertible turbidity happens in the depectinized red raspberry juice under refrigeration. Its analysis is carried out: --Chemically: Total sugar determination by anthrone methol, galacturonic acid determination by carbazol, total nitrogen determination according to Berthelot's coloured reaction (automated analysis) -- Physically: Calcium, potassium and magnesium determinations by atomic absorption. -- Chromatographically: Sugar separation and determination by HPLC. M. W. determination of the different entites by GPC (gel Sephadex G 100). Pectic substances separation on DEAE-cellulose column. The turbidity ensues from an enhanced by cold and acidic pH flocculation process which occurs between the large nitrogeneous molecules (inactive and enzymic proteins mainly). M. W. (superior to 150.000) of the depectinizing preparation and rich in glucose and mannose polysaccharidiques (M. W. between the range from 1.000 to 10.000) accompanied by aldobiuronic units. The origin of the manno-glucan entity remains to be determined. It could be issued either a limit-substrate produced by the degradation of the raspberry pectic substances or an by Aspergillus niger excreted compound.
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PMID:[Proteo-polysaccharidic turbidity in depectinized raspberry juice]. 75 86

Papain (EC 3.4.22.2) is a proteolytic enzyme, the three-dimensional structure of which has been determined by x-ray diffraction at 2.8 A resolution (Drenth, J., Jansonius, J.N., Koekoek, R., Swen, H. M., and Wothers, B.G. (1968), Nature (London) 218, 929-932). The active site is a groove on the molecular surface in which the essential sulfhydryl group of cysteine-25 is situated next to the imidazole ring of histidine-159. The main object of this study was to determine by the difference-Fourier technique the binding mode for the substrate in the groove in order to explain the substrate specificity of the enzyme (P2 should have a hydrophobic side chain (Berger and Schechter, 1970) and to contribute to an elucidation of the catalytic mechanism. To this end, three chloromethyl ketone substrate analogues were reacted with the enzyme by covalent attachment to the sulfur atom of cysteine-25. The products crystallized isomorphously with the parent structure that is not the native, active enzyme but a mixture of oxidized papain (probably papain-SO2-) and papain with an extra cysteine attached to cysteine-25. Although this made the interpretation of the difference electron density maps less easy, it provided us with a clear picture of the way in which the acyl part of the substrate binds in the active site groove. The carbonyl oxygen of the P1 residue is near two potential hydrogen-bond donating groups, the backbone NH of cysteine-25 and the NH2 of glutamine-19. Valine residues 133 and 157 are responsible for the preference of papain in its substrate splitting. By removing the methylene group that covalently attaches the inhibitor molecules to the sulfur atom of cysteine-25 we obtained acceptable models for the acyl-enzyme structure and for the tetrahedral intermediate. The carbonyl oxygen of the P1 residue, carrying a formal negative charge in the tetrahedral intermediate, is stabilized by formation of two hydrogen bonds with the backbone NH of cysteine-25 and the NH2 group of glutamine-19. This situation resembles that suggested for the proteolytic serine enzymes (Henderson, R., Wright, C. S., Hess, G. P., and Blow, D. M. (1971), Cold Spring Harbor Symp. Quant. Biol. 36, 63-70; Robertus, J. D., Kraut, J., Alden, R. A., and Birktoft, J. J. (1972b), Biochemistry 11, 4293-4303). The nitrogen atom of the scissile peptide bond was found close to the imidazole ring of histidine-159, suggesting a role for this ring in protonating the N atom of the leaving group (Lowe, 1970). This proton transfer would be facilitated by a 30 degrees rotation of the ring around the C beta-Cgamma bond from an in-plane position with the sulfur atom to an in-plane position with the N atom. The possibility of this rotation is derived from a difference electron-density map for fully oxidizied papain vs. the parent protein.
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PMID:Binding of chloromethyl ketone substrate analogues to crystalline papain. 95 85

The relationship of efficiency of efficiency of feed utilization with metabolizable energy derived from the diet and nitrogen retention was studied in broiler strains and in lines selected for divergence in feed conversion ratio. Individual feed conversion (g feed/g gain) and metabolizable energy derived from the diet and nitrogen retention (determined by chromic oxide method) of these strains and lines were measured, and correlations were determined at various intervals from 4 to 9 weeks of age to determine the effects of age, sex, strain, feed conversion, growth, and feed consumption on the metabolizable energy derived from the diet and nitrogen retained. Although there were significant differences in feed conversion between sexes, strains, and lines selected for divergence in feed conversion, there were no associated differences in metabolizable energy derived from the diet or in nitrogen retention. There were no significant correlations of consumption, growth, or feed conversion with metabolizable energy derived from the diet or nitrogen retention. Nitrogen retention of the White Plymouth Rock strain was significantly higher for all ages. These results show that differences observed in growth, consumption, or feed conversion do not influence derivation of metabolizable energy from the diet or nitrogen retention.
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PMID:Influence of genetic differences in feed efficiency of young chickens on derivation of metabolizable energy from the diet and nitrogen retention. 114 2


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