scholarly journals A pulse-radiolysis study of the manganese-containing superoxide dismutase from Bacillus stearothermophilus

1977 ◽  
Vol 165 (1) ◽  
pp. 81-87 ◽  
Author(s):  
M E McAdam ◽  
F Levelle ◽  
R A Fox ◽  
E M Fielden
Keyword(s):  
Superoxide Dismutase ◽  
Enzyme Activity ◽  
Substrate Concentration ◽  
Radical Anion ◽  
Pulse Radiolysis ◽  
Bacillus Stearothermophilus ◽  
Preceding Paper ◽  
Native Enzyme ◽  
Arrhenius Parameters ◽  
Mechanism Of Catalysis

In the preceding paper the mechanism of catalysis of the manganese-containing superoxide dismutase from Bacillus stearothermophilus was shown to involve a ‘fast cycle’ and a ‘slow cycle’ [McAdam, Fox, Lavelle & Fielden, 1977 (Biochem. J. 165, 71-79)]. Further properties of the enzyme was considered in the present paper. Pulse-radiolysis studies, under conditions of low substrate concentration to (i.e. when the fast cycle predominates), showed that enzyme activity decreases as pH increases (6.5-10.2). Activity was unaffected by the addition of H2O2 or NaN3 but slightly decreased by KCN. Both H2O2 and the reducing radical anion CO2– caused a decrease in A480 of the native enzyme. The rate of the fast catalytic cycle was independent of temperature (5-55 degrees C), and as temperature increases the slow cycle becomes relatively more important. Arrhenius parameters of the rate contants were estimated. The possible identity of the various forms of the enzyme is considered.

scholarly journals A pulse-radiolysis study of the manganese-containing superoxide dismutase from Bacillus stearothermophilus. A kinetic model for the enzyme action

1977 ◽  
Vol 165 (1) ◽  
pp. 71-79 ◽  
Author(s):  
M E McAdam ◽  
R A Fox ◽  
F Lavelle ◽  
E M Fielden
Keyword(s):  
Superoxide Dismutase ◽  
Pulse Radiolysis ◽  
Bacillus Stearothermophilus ◽  
Enzyme Concentration ◽  
Native Enzyme ◽  
Visible Absorption ◽  
Oxidation Reduction ◽  
Reduction Cycle ◽  
Computer Calculations ◽  
Kinetics Of

The enzymic reaction mechanism of a manganese-containing superoxide dismutase from Bacillus stearothermophilus was studied by using pulse radiolysis. During catalysis (pH 8.9; 25 degrees C), changes occurring in the kinetics of substrate disappearance and in the visible absorption of the enzyme at 480 nm established that the simple two-step mechanism found for copper- and iron-containing superoxide dismutases is not involved. At a low ratio (less than 15) of substrate concentration to enzyme concentration the decay of O2–is close to exponetial, whereas at much higher ratios (greater than 100) the observed decay is predominantly zero-order. The simplest interpretation of the results invokes a rapid one-electron oxidation-reduction cycle (‘the fast cycle’) and, concurrently, a slower reaction giving a form of the enzyme that is essentially unreactive towards O2– but which undergoes a first-order decay to yield fully active native enzyme (‘the slow cycle’). The fast cycle involves the native enzyme EA and a form of the enzyme EB which can be obtained also by treating the form EA with H2O2. Computer calculations made with such a simple model predict behaviour in excellent agreement with the observed results.

Amino acids flanking the central core of Cu,Zn superoxide dismutase are important in retaining enzyme activity after autoclaving

2016 ◽  
Vol 34 (3) ◽  
pp. 475-485 ◽  
Author(s):  
Arun Kumar ◽  
Vinay Randhawa ◽  
Vishal Acharya ◽  
Kashmir Singh ◽  
Sanjay Kumar
Keyword(s):  
Amino Acids ◽  
Superoxide Dismutase ◽  
Enzyme Activity ◽  
Central Core

β-GLUCURONIDASE OF RABBIT POLYMORPHONUCLEAR LEUCOCYTES

1950 ◽  
Vol 28e (3) ◽  
pp. 69-79 ◽  
Author(s):  
R. J. Rossiter ◽  
Esther Wong
Keyword(s):  
Enzyme Activity ◽  
Blood Plasma ◽  
Substrate Concentration ◽  
Final Concentration ◽  
White Cell ◽  
Polymorphonuclear Leucocytes ◽  
Michaelis Constant ◽  
Glucuronidase Activity ◽  
Arsanilic Acid ◽  
Optimum Ph

Rabbit polymorphonuclear leucocytes contain an enzyme capable of hydrolyzing biosynthetic phenolphthalein mono-β-glucuronide. The concentration of the enzyme in the white cell is some 2000 times the concentration of the enzyme in the blood plasma. Under the conditions of study, the β-glucuronidase activity was proportional to the concentration of the enzyme. The effect of substrate concentration on the enzyme activity was studied and the Michaelis constant, Ks, determined. The course of the reaction was linear with time for the first 12 hr. and then fell off slightly during the next 12 hr. The optimum pH of the enzyme was 4.45 in either 0.2 M acetate or 0.2 M phthalate buffer. It was not inhibited by cyanide, azide, iodoacetate, fluoride, glycine, thiourea, urethane, arsanilic acid, acetophenone, o-cresol or m-cresol, in a final concentration of 0.01 M. The possible function of β-glucuronidase in rabbit polymorphonuclear leucocytes is discussed.

Stressed Response of Submerged Elodea nattalii under Eutrophication Growth Conditions

2012 ◽  
Vol 610-613 ◽  
pp. 229-234
Author(s):  
Han Feng Xiong ◽  
Qi Ling Tan
Keyword(s):  
Superoxide Dismutase ◽  
Enzyme Activity ◽  
Aquatic Plants ◽  
Nutrient Concentration ◽  
Growth Conditions ◽  
Antioxidant Enzyme Activity ◽  
Metabolic Responses ◽  
Concentration Increase ◽  
Time Period ◽  
Mda Content

Eutrophication in water bodies affects the growth of aquatic plants. In this study, we conducted static experiments to better understand the metabolic responses of Elodea nattalii under eutrophication conditions. The nitrogen (N) and phosphorous (P) levels in tissue, malondiadehyde (MDA), and activities of three antioxidases (peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)) of Elodea nattalii cultured at different nutrient levels (oligotropher, mesotropher, eutropher, and hypertrophics) were investigated. The results showed that with nutrient concentration increase, N and P contents of Elodea nattalii increased. The MDA content improved with nutrient increase. the POD activity initially increased and later decreased. CAT and SOD activities decreased during the experimental time period. These finding suggested that changes in stem the increase of antioxidant enzyme activity can be served as the indicators of the response of Elodea nattalii to eutrophication conditions.

scholarly journals Вплив хлориду кадмію на стан антиоксидантної системи у печінці щурів

2013 ◽  
pp. 102-103
Author(s):  
Б. В. Гутий
Keyword(s):  
Lipid Peroxidation ◽  
Superoxide Dismutase ◽  
Enzyme Activity ◽  
Glutathione Peroxidase ◽  
Antioxidant System ◽  
Cadmium Chloride

Розкрито особливості антиоксидантної системиорганізму щурів за хронічного кадмієвого токсикозу.Встановлено, що хлорид кадмію у токсичній дозісприяє зниженню активності ферментної й нефер-ментної системи антиоксидантного захисту, на щовказує зниження ферментів глутатіонпероксидази,глутатіонредуктази, супероксиддисмутази, катала-зи та відновленого глутатіону у печінці щурів. Ре-зультати досліджень вказують на те, що хронічнийкадмієвий токсикоз призводить до посиленої акти-вації процесів ліпопероксидації. The features of the antioxidant system of rats with chronic cadmium toxicosiare disclosed. It wasresearched that cadmium chloride in toxic doses reduces enzyme activity of antioxidant system, asindicated by the decrease in enzyme glutathione peroxidase, hlutationreduktazy, superoxide dismutase,catalase and restored glutathione in the liver and blood of rats. The results indicate that chroniccadmium toxicosis leads to enhanced activation of lipid peroxidation.

scholarly journals THE CORRELATION BETWEEN FAT INTAKE AND PLASMA SUPEROXIDE DISMUTASE ACTIVITY WITH TELOMERE LENGTH OF MINANGKABAU ETHNICITY MEN, IN WEST SUMATERA, INDONESIA

2019 ◽  
pp. 305-309
Author(s):  
AFRIWARDI AFRIWARDI ◽  
DELMI SULASTRI ◽  
YUNIAR LESTARI ◽  
DESMAWATI DESMAWATI ◽  
PRIMA MINERVA
Keyword(s):  
Superoxide Dismutase ◽  
Enzyme Activity ◽  
Fatty Acid ◽  
Telomere Length ◽  
Saturated Fatty Acids ◽  
Cross Sectional Study ◽  
Fat Intake ◽  
Sod Activity ◽  
Cross Sectional ◽  
Total Fat

Objective: The purpose of this research is to investigate the correlation between fat intake and plasma superoxide dismutase (SOD) enzyme activity with telomere length of Minangkabau ethnic men in West Sumatera, Indonesia. Materials and Methods: This cross-sectional study was conducted in Padang City in 2016, using a sample of 107 Minangkabau ethnic men, aged between 40 and 50 years. The total fat, saturated fatty acids (SFA), monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA) intake were collected using a food frequency questionnaire, and blood sample analysis to measure telomere length and plasma SOD activity. Results: This research indicated that an average telomere length was 584.59±305.92 bp, fat intake consists of total fat was 27.01±6.68% calorie, SFA was 24,7510.07% calorie, MUFA was 10.24±5.41% calorie, and PUFA was 7.35±3.54% calorie. Average of plasma SOD activity was 5.85±3.41 u/mL. There were no correlations between fat intake (total fat, SFA, MUFA, and PUFA) with telomere length (p>0.05), but there was a significant positive correlation between plasma SOD enzyme activity with telomere length (r=−0.202, p=0.037). Conclusion: Fat intake within normal limits does not correlate with telomere length, and plasma SOD activity is a risk factor for telomere shortening in ethnic Minangkabau men.

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