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  • 1
    Electronic Resource
    Electronic Resource
    Alanine dehydrogenase of the N2-fixing blue-green alga, Anabaena cylindrica (1976)
    Springer
    Archives of microbiology 107 (1976), S. 115-124 
    Details
    ISSN: 1432-072X
    Keywords: Alanine dehydrogenase ; Anabaena cylindrica ; Heterocysts ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The l-alanine dehydrogenase (ADH) of Anabaena cylindrica has been purified 700-fold. It has a molecular weight of approximately 270000, has 6 sub-units, each of molecular weight approximately 43000, and shows activity both in the aminating and deaminating directions. The enzyme is NADH/NAD+ specific and oxaloacetate can partially substitute for pyruvate. The K m app for NAD+ is 14 μM and 60 μM at low and high NAD+ concentrations, respectively. The K m app for l-alanine is 0.4 mM, that for pyruvate is 0.11 mM, and that for oxaloacetate is 3.0 mM. The K m app for NH 4 + varies from 8–133 mM depending on the pH, being lowest at high pH levels (pH 8.7 or above). Alanine, serine and glycine inhibit ADH activity in the aminating direction. The enzyme is active both in heterocysts and vegetative cells and activity is higher in nitrogen-starved cultures than in N2-fixing cultures. The data suggest that although alanine is formed by the aminating activity of ADH, entry of newly fixed ammonia into organic combination does not occur primarily via ADH in N2-fixing cultures of A. cylindrica. Ammonia assimilation via ADH may be important in cultures with an excess of available nitrogen. The deaminating activity of the enzyme may be important under conditions of nitrogen-deficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446830
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  • 2
    Electronic Resource
    Electronic Resource
    Cellular compartmentation of photosynthetic and photorespiratory enzymes in the heterocystous cyanobacterium Anabaena cylindrica (1980)
    Springer
    Archives of microbiology 124 (1980), S. 149-154 
    Details
    ISSN: 1432-072X
    Keywords: Phosphoribulokinase ; d-ribulose 1,5-bisphosphate carboxylase-oxygenase ; Phosphoglycollate phosphatase ; Glycollate dehydrogenase ; Heterocysts ; Anabaena cylindrica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activities of enzymes of photosynthesis and photorespiration have been measured in extracts of vegetative cells and heterocysts from the filamentous cyanobacterium Anabaena cylindrica. Phosphoribulokinase, d-ribulose 1,5-bisphosphate carboxylase/oxygenase, phosphoglycollate phosphatase and glycollate dehydrogenase activities were readily measured in vegetative cell extracts, but were undetectable or negligible in heterocyst preparations. The data help to explain why heterocysts are unable to perform photosynthetic CO2 fixation. They also exemplify the co-ordinate compartmentation of enzymes of photosynthesis and photorespiration which occur in a differentiated phototrophic prokaryote.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427720
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Alteration of cyanobacterial glutamine synthetase activity in vivo in response to light and NH 4 + (1979)
    Springer
    Archives of microbiology 120 (1979), S. 195-200 
    Details
    ISSN: 1432-072X
    Keywords: Blue-green algae ; Cyanobacteria ; Glutamine synthetase ; Light-modulation ; Anabaena cylindrica ; NH 4 + -deactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extractable glutamine synthetase activity of the cyanobacterium Anabaena cylindrica was reduced by approximately 50% when N2-fixing cultures were treated with 10 mM NH 4 + or were placed in darkness. The deactivated enzyme could be rapidly reactivated (within 5 min) by adding 40 mM 2-mercaptoethanol to the biosynthetic reaction mixture. The enzyme could also be reactivated in vivo by replacing the culture in light or by removing NH 4 + . When the enzyme was deactivated by simultaneously adding NH 4 + and placing the culture in darkness, reactivation occurred on reillumination and removal of NH 4 + . The removal of NH 4 + in darkness did not result in reactivation. On in vitro reactivation of glutamine synthetase from dark or NH 4 + -treated cultures the maximum glutamine synthetase activity observed frequently exceeded that of glutamine synthetase extracted from untreated cultures. Anacystis nidulans showed a similar type of reversible dark deactivation to A. cylindrica but Plectonema boryanum and a Nostoc did not. With A. cylindrica, a direct positive correlation between the size of the intracellular pool of glutamate and biosynthetic glutamine synthetase activity occurred during light/dark shifts, and on treatment with NH 4 + . The changes in activity of glutamine synthetase in A. cylindrica in response to light resemble in some respects the light modulation of enzymes of the oxidative and reductive pentose phosphate pathways noted in cyanobacteria by others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423065
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  • 4
    Electronic Resource
    Electronic Resource
    ATP pools and transients in the blue-green alga, Anabaena cylindrica (1976)
    Springer
    Archives of microbiology 108 (1976), S. 249-258 
    Details
    ISSN: 1432-072X
    Keywords: Anabaena cylindrica ; ATP pools ; ATP transients ; Phosphorylating mechanisms ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anabaena cylindrica grown in steady state continuous culture has an extractable ATP pool, measured on the basis of the luciferin-luciferase assay of 165±35 nmoles ATP mg chla -1. This pool is maintained by a dynamic balance between the rate of ATP synthesis and the rate of ATP utilization. Phosphorylating mechanisms which can maintain the pool in the short term are total photophosphorylation, cyclic photophosphorylation and oxidative phosphorylation. The alga can maintain its ATP pool by switching rapidly from one of these phosphorylating mechanisms to another depending on the environmental conditions. At each switch-over there is a transient drop in the ATP pool for a few seconds. On switching to conditions where only substrate level phosphorylation operates, the ATP pool falls immediately, but takes several hours to recover. The apparent rates of ATP synthesis by total photophosphorylation and by cyclic photophosphorylation are both much higher (210±30 and 250±13 μmoles ATP mg chla -1 h-1 respectively) than the apparent rate of ATP synthesis by oxidative phosphorylation (22±3 μmoles ATP mg chla -1 h-1). In long term experiments the ATP pool is maintained when total photophosphorylation is operating. It cannot be maintained in the long term by cyclic photophosphorylation alone in the absence of photosystem II activity or endogenous carbon compounds, or by oxidative phosphorylation in the absence of endogenous carbon compounds. Measurements of ATP, ADP and AMP show that the total pool of adenylates is similar in the light and in the dark in the short term. There is only limited production of ATP under dark anaerobic conditions when glycolysis and substrate phosphorylation can operate which suggests that these processes are of limited significance in providing ATP in Anabaena cylindrica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454849
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    Paper (German National Licenses)
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