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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 24 (1977), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Mitochondria were isolated from Euglena gracilis strain Z by pressure-breakage of the cells and sucrose-cushion centrifugation. Multiple peaks (2-4) were observed in the rate of phosphorylation with Mg-ADP-phosphate concentration curves. The phosphorylative and oxidative activities were highest with NADH as the substrate, moderate with succinate, and lowest with glutamate. Inhibition of phosphorylation with 2,4-dinitrophenol and carbonyl cyanide, m-chlorophenylhydrazone gave sigmoidal concentration curves, with the extent of inhibition by DNP depending on the substrate used. Inhibition of phosphorylation by valinomycin, atractyloside, or carboxyatractyloside was only ∼ 60%. Oligomycin inhibited phosphorylation in 2 phases at low and high concentrations; it inhibited Mg-ATPase in a sigmoidal fashion. Both phosphorylation and oxidation had discontinuities in Arrhenius plots at 34 C and 18 C.The relative Mg2+-dependent nucleoside triphosphatase activity was: 1 for ATP and GTP, 0.6 for ITP, 0.15 for CTP and and UTP; with Ca2+ in place of Mg2+ this activity was 0.35. Both DNP and CCCP stimulated the Mg-ATPase 50-200%. The optimal pH for the stimulation was ∼ 7 regardless of the uncoupler used, and ∼ 8 without the uncouplers.The few differences observed between mitochondria from Euglena and those from other sources are probably due to the fragmentation of the reticular mitochondrial structure during isolation and not to unique characteristics of these mitochondria.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 533 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 468 (1986), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 462 (1986), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 540 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 41 (1976), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The degree of browning produced from the oxidation of 4-methyl catechol by Lerman and Fuerte avocado PPO was affected by the presence of various phenol-type compounds which could not, by themselves, act as substrates for the enzyme. P-coumaric acid, protocatechuic acid and p-cresol arrested the development of dark-colored o-quinones, while phloroglucinol, orcinol and resorcinol markedly increased their formation. Similar relative effects were obtained with PPO of either avocado source.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 42 (1977), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The browning potential of avocado fruits of the Fuerte and Lerman cultivars was determined in fruits which were cut and exposed to air at 20°C. Analyses of the changes in tristimulus color parameters showed that the total change in color as defined by δE depends mostly on the change in lightness (δL) which has a linear relationship to exposure time of 210 min. The browning potential of Fuerte was much greater than the browning potential of Lerman and in both cultivars it was greater at the distal (blossom) ends compared with the proximal (stem) ends of the fruits. It was also found that the browning potential is dependent on the length of the storage period after harvest and an increase which roughly corresponded to the climacteric was observed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 52 (1987), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Starch granules of avocado seeds were oval shaped with a relatively smooth surface and an average diameter of 5–35μ. The starch was nonionic and not waxy. The gelatinization temperature range of the starch was 62–75°C. Brabender viscosity curves showed that the starch had restricted swelling with no pronounced pasting peak but with good pasting stability and average set back on cooling. Avocado seed starch exhibited type B x-ray diffraction pattern.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 42 (1977), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biochemical properties of polyphenoloxidase (PPO) from Lerman and Fuerte avocado varieties, which differ in their rates of browning, were studied. The partially purified PPO from either source had a pH optimum around 5.5–6.5 and was characterized by a relatively high stability to heat. PPO of Lerman and Fuerte avocado exhibited fairly similar substrate specificity, with a higher activity toward 4-methyl catechol, pyrogallol or dopamine and a lower one toward catechm, caffeic acid or chlorogenic acid. No lactase or cresolase activity was detected with either enzyme. The effect of several types of PPO inhibitors was tested and it was found that, with minor exceptions, the two enzymes responded similarly. PPO of both sources exhibited similar relative activities toward most of the o-dihydroxyphenols tested and, as reported earlier, similar isoenzyme patterns were obtained with DL-DOPA, caffeic acid, chlorogenic acid, and 4-methyl catechol. It can therefore be concluded that the higher rate of browning observed when freshly cut Fuerte is exposed to air, as compared with Lerman, is unlikely to result from a difference in the properties of the PPO enzymes in each of these varieties. Instead, it may be directly correlated to the amount of PPO activity present per gram wet weight and/or the concentrations of the natural substrates present.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 50 (1985), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Casein hydrolyzate and bovine serum albumin did not inhibit the o-dihydroxyphenolase activity of polyphenol oxidase of avocado and mushroom. L-lysine, glycine, L-histidine and L-phenylalanine, in increasing order of effectiveness, inhibited o-dihydroxyphenolase activity to a maximum of about 60% inhibition only; 50% inhibition was observed with 50 mM L-phenylalanine vs. 160 mM L-lysine. L-cysteine at about 0.4 mM gave full inhibition. Triglycine, diglytine and glycine, in decreasing order, were effective in lowering the final level of colored melanin formed by the action of polyphenol oxidase on DL-DOPA. Amino acids are nontoxic and could be safely added to food during processins as a means of preventing undesirable enzymatic browning.
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