scholarly journals The effects of anions on fumarate reductase isolated from the cytoplasmic membrane of Escherichia coli

1981 ◽  
Vol 199 (3) ◽  
pp. 473-477 ◽  
Author(s):  
J J Robinson ◽  
J H Weiner
Keyword(s):  
Escherichia Coli ◽  
Cytoplasmic Membrane ◽  
Chemical Properties ◽  
Fumarate Reductase ◽  
Maximal Velocity ◽  
Nitrobenzoic Acid ◽  
Thiol Reagent ◽  
Membrane Bound ◽  
Physical And Chemical ◽  
And Chemical Properties

A broad range of anions was shown to stimulate the maximal velocity of purified fumarate reductase isolated from the cytoplasmic membrane of Escherichia coli, while leaving the Km for fumarate unaffected. Reducing agents potentiate the effects of anions on the activity, but have no effect by themselves. Thermal stability, conformation as monitored by circular dichroism and susceptibility to the thiol reagent 5,5′-dithiobis-(2-nitrobenzoic acid) are also altered by anions. The apparent Km for succinate in the reverse reaction (succinate dehydrogenase activity) varies as a function of anion concentration, but the maximal velocity is not affected. The membrane-bound activity is not stimulated by anions and its properties closely resemble those of the purified enzyme in the presence of anions. Thus it appears that anions alter the physical and chemical properties of fumarate reductase, so that it more closely resembles the membrane-bound form.

Molecular properties of fumarate reductase isolated from the cytoplasmic membrane of Escherichia coli

1982 ◽  
Vol 60 (8) ◽  
pp. 811-816 ◽  
Author(s):  
John J. Robinson ◽  
Joel H. Weiner
Keyword(s):  
Escherichia Coli ◽  
Rhodospirillum Rubrum ◽  
Cytoplasmic Membrane ◽  
Reductase Activity ◽  
Sulfhydryl Group ◽  
Fumarate Reductase ◽  
Molar Ratio ◽  
Heart Mitochondrion ◽  
Visible Absorption ◽  
Nitrobenzoic Acid

Fumarate reductase, purified from the cytoplasmic membrane of Escherichia coli, has been cross-linked with the bifunctional reagent dimethylsuberimidate and shown to exist as an αβ dimer of polypeptides of molecular weights 69 000 and 25 000 in a 1:1 molar ratio. The protein has an s20,W of 7.67S and a D20,W of 6.5 × 10−7 cm2/s. The purified enzyme contained 4–5 mol of nonheme iron and 4–5 mol of acid labile sulfur while the visible absorption spectrum showed a broad peak between 400 and 470 nm owing to the presence of an Fe–S centre and 8α[N-3]histidyl FAD. Fumarate reductase activity was readily inhibited by the sulfhydryl reagents 5,5′-dithiobis-(2-nitrobenzoic acid), p-chloromercuribenzoate, and iodoacetamide. Using 5,5′-dithiobis-(2-nitrobenzoic acid) sulfhydryl group modification was followed as a function of enzyme activity. A single cysteine residue was shown to be required for activity and this essential sulfhydryl group was located in the 69 000 dalton subunit. The amino acid composition of E. coli fumarate reductase was similar to the succinate dehydrogenases from beef heart mitochondrion and Rhodospirillum rubrum.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Tailoring microstructures of materials through biomimetics

1993 ◽  
Vol 51 ◽  
pp. 500-501
Author(s):  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Chemical Properties ◽  
Design And Synthesis ◽  
Structure Sensitive ◽  
Macro Scale ◽  
Methods Of Synthesis ◽  
Successive Level ◽  
Engineering Materials ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Synthesis Of Materials

Biomimetics involves investigation of structure, function, and methods of synthesis of biological composite materials. The goal is to apply this information to the design and synthesis of materials for engineering applications.Properties of engineering materials are structure sensitive through the whole spectrum of dimensions from nanometer to macro scale. The goal in designing and processing of technological materials, therefore, is to control microstructural evolution at each of these dimensions so as to achieve predictable physical and chemical properties. Control at each successive level of dimension, however, is a major challenge as is the retention of integrity between successive levels. Engineering materials are rarely fabricated to achieve more than a few of the desired properties and the synthesis techniques usually involve high temperature or low pressure conditions that are energy inefficient and environmentally damaging.In contrast to human-made materials, organisms synthesize composites whose intricate structures are more controlled at each scale and hierarchical order.

Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno
Keyword(s):  
Block Design ◽  
Management Strategies ◽  
Chemical Properties ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Physical And Chemical Properties ◽  
Total N ◽  
Randomized Complete Block Design ◽  
Physical And Chemical ◽  
And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

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