scholarly journals A new enzyme for the interconversion of pyruvate and phosphopyruvate and its role in the C4 dicarboxylic acid pathway of photosynthesis

1968 ◽  
Vol 106 (1) ◽  
pp. 141-146 ◽  
Author(s):  
M. D. Hatch ◽  
C. R. Slack
Keyword(s):  
Zea Mays ◽  
Dicarboxylic Acid ◽  
Sugar Cane ◽  
Sorghum Vulgare ◽  
Leaf Extracts ◽  
Tropical Grasses ◽  
Thiol Compound ◽  
Acid Pathway

1. An enzyme was isolated from leaves of tropical grasses that catalyses the reversible conversion of pyruvate, ATP and orthophosphate into phosphopyruvate, AMP and pyrophosphate. A requirement for Mg2+ could not be replaced by Mn2+ or Ca2+. 2. By replacing orthophosphate with [32P]orthophosphate or with arsenate, evidence was provided that the orthophosphate consumed appears in pyrophosphate. 3. Without Mg2+ or 2-mercaptoethanol the enzyme was rapidly and irreversibly inactivated. EDTA only partially replaced the requirement for the thiol compound. The enzyme was considerably more unstable at 0° or when frozen than at 22°. Even with the best conditions devised the enzyme lost about 25% of its activity every 3hr. 4. The activities of the enzyme in leaves of the tropical grasses sugar cane (Saccharum hybrid var. Pindar), maize (Zea mays) and sorghum (Sorghum vulgare) were comparable with their maximum photosynthesis rates. The enzyme was not detectable in leaf extracts from several other plants. 5. Its role in photosynthesis is discussed.

scholarly journals Properties and regulation of leaf nicotinamide–adenine dinucleotide phosphate–malate dehydrogenase and ‘malic’ enzyme in plants with the C4-dicarboxylic acid pathway of photosynthesis

1970 ◽  
Vol 119 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Hilary S. Johnson ◽  
M. D. Hatch
Keyword(s):  
Dicarboxylic Acid ◽  
Malate Dehydrogenase ◽  
Malic Enzyme ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Maximum Velocity ◽  
Enzyme Reaction ◽  
Reverse Direction ◽  
Leaf Extracts ◽  
Ph Optimum ◽  
Acid Pathway

1. NADP–malate dehydrogenase and `malic' enzyme in maize leaf extracts were separated from NAD–malate dehydrogenase and their properties were examined. 2. The NADP–malate dehydrogenase was nicotinamide nucleotide-specific but otherwise catalysed a reaction comparable with that with the NAD-specific enzyme. By contrast with the latter enzyme, a thiol was absolutely essential for maintaining the activity of the NADP–malate dehydrogenase, and the initial velocity in the direction of malate formation, relative to the reverse direction, was faster. 3. For the `malic' enzyme reaction the Km for malate was dependent on pH and the pH optimum varied with the malate concentration. At their respective optimum concentrations the maximum velocity for this enzyme was higher with Mg2+ than with Mn2+. 4. The NADP–malate dehydrogenase in green leaves was rapidly inactivated in the dark and was reactivated when plants were illuminated. Reactivation of the enzyme extracted from darkened leaves was achieved simply by adding a thiol compound. 5. The activity of both enzymes was low in etiolated leaves of maize plants grown in the dark but increased 10–20-fold, together with chlorophyll, when leaves were illuminated. 6. The activity of these enzymes in different species with the C4-dicarboxylic acid pathway was compared and their possible role in photosynthesis was considered.

scholarly journals The activity of uridine diphosphate glucose–d-fructose 6-phosphate 2-glucosyltransferase in leaves

1967 ◽  
Vol 105 (3) ◽  
pp. 943-946 ◽  
Author(s):  
J. S. Hawker
Keyword(s):  
Sugar Cane ◽  
Sucrose Synthesis ◽  
Uridine Diphosphate ◽  
Leaf Extracts ◽  
Uridine Diphosphate Glucose ◽  
Rate Of Photosynthesis ◽  
Diphosphate Glucose ◽  
Sucrose Phosphate Synthetase ◽  
High Sucrose ◽  
Sucrose Phosphate

1. By using EDTA in reaction mixtures it was possible to determine the activity of sucrose phosphate synthetase in freshly prepared leaf extracts without the complications caused by sucrose phosphatase. 2. EDTA was found also to increase the activity of sucrose phosphate synthetase by as much as 100%. 3. High sucrose phosphate synthetase activities were found in leaf preparations in which sucrose phosphatase was inhibited by EDTA. By contrast with previous reports, the activities were sufficient to allow sucrose synthesis in leaves during photosynthesis to occur via sucrose phosphate. 4. Sugar-cane plants having different rates of photosynthesis also had different activities of sucrose phosphate synthetase in their leaves. 5. It is suggested that the activity of sucrose phosphate synthetase in leaves may play a role in the control of the rate of photosynthesis.

Cochliobolus heterostrophus. [Descriptions of Fungi and Bacteria].

1971 ◽  
Author(s):  
M. B. Ellis
Keyword(s):  
Zea Mays ◽  
Geographical Distribution ◽  
Leaf Sheath ◽  
Leaf Blight ◽  
Disease Spread ◽  
Cochliobolus Heterostrophus ◽  
Sorghum Vulgare ◽  
Main Host ◽  
The Tropics ◽  
Diffuse Lesion

Abstract A description is provided for Cochliobolus heterostrophus. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Generally on leaves of Zea mays, the main host, Euchlaena mexicana, Sorghum vulgare and many species of Gramineae (41: 40; 45, 3084; 48, 414; 50, 2257i). During an epidemic in USA caused by race T in 1970 no important hosts apart from Z. mays were noted (50, 2257b). DISEASE: Southern leaf blight of maize, forming very numerous lesions up to 2.5 cm long, mostly on the leaves. They are at first elliptical, then longitudinally elongate, becoming rectangular as restriction by the veins occurs; cinnamon-buff (sometimes with a purplish tint) with a reddish-brown margin and occasionally zonate, coalescing and becoming greyish with conidia. Symptoms caused by race T show a less well defined, somewhat diffuse lesion, with marginal chlorosis leading to leaf collapse, and all parts of the plant can be attacked. Perithecia have been recently reported in the field at the junction of leaf sheath and blade (50, 2257j). GEOGRAPHICAL DISTRIBUTION: Widespread in the tropics and subtropics (CMI Map 346, ed. 3, 1969) but not reported from Australia. Records not yet mapped are: Brunei, Guatemala, Hawaii, Israel, Laos, Mexico, Salvador and Venezuela. TRANSMISSION: Presumably air-dispersed but no detailed studies seem to have been reported. During the recent USA outbreak the disease spread from Florida to Maine in c. 6 months (50, 2257c). Spread by seed occurs (50, 3690, 3692; Crosier & Boothroyd, Phytopathology 61: 427, 747).

scholarly journals Enhancing the Decolorizing and Degradation Ability of Bacterial Consortium Isolated from Textile Effluent Affected Area and Its Application on Seed Germination

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Rashid Mahmood ◽  
Faiza Sharif ◽  
Sikander Ali ◽  
Muhammad Umar Hayyat
Keyword(s):  
Zea Mays ◽  
Ascorbic Acid ◽  
Sodium Chloride ◽  
Seed Germination ◽  
Bacterial Consortium ◽  
Textile Effluent ◽  
Sorghum Vulgare ◽  
Affected Area ◽  
Individual Strain ◽  
Degradation Ability

A bacterial consortium BMP1/SDSC/01 consisting of six isolates was isolated from textile effected soil, sludge, and textile effluent from Hudiara drain near Nishat Mills Limited, Ferozepur Road, Lahore, Pakistan. It was selected because of being capable of degrading and detoxifying red, green, black, and yellow textile dyes. The pH and supplements were optimized to enhance the decolorization ability of the selected consortium. The results indicated that decolorizing ability of consortium for the red, green, black, and yellow dyes was higher as compared to individual strains. The consortium was able to decolorize 84%, 84%, 85%, 85%, and 82% of 200 ppm of red, green, black, yellow, and mixed dyes within 24 h while individual strain required 72 h. On supplementing urea, the consortium decolorized 87, 86, 89, 86, and 83%, respectively, while on supplementing sodium chloride the consortium decolorized 93, 94, 93, 94, and 89% of red, green, black, yellow, and mixed dyes, respectively, which was maximum while in the presence of ascorbic acid and ammonium chloride it showed intermediate results. The effect of untreated and treated dyes was investigated onZea maysL. (maize) andSorghum vulgarePers. (sorghum). This study will help to promote an efficient biotreatment of textile effluents.

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