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.

KINETIC STUDIES ON ACID PHOSPHATASE IN TRIBOLIUM CONFUSUM DUVAL

1964 ◽  
Vol 42 (12) ◽  
pp. 1769-1775 ◽  
Author(s):  
K. D. Chaudhary ◽  
S. Moorjani ◽  
A. Lemonde
Keyword(s):  
Kinetic Studies ◽  
Final Concentration ◽  
Tribolium Confusum ◽  
Metallic Ions ◽  
Optimal Conditions ◽  
Optimum Temperature ◽  
Apparent Effect ◽  
Michaelis Constant ◽  
Optimum Ph ◽  
Zero Order Reaction

The biochemical characteristics of acid phosphomonoesterase in Tribolium confusum homogenate have been determined. Zero-order reaction occurs for 30 minutes, with 10−3 M final concentration of phenyl phosphate at an optimum pH of 6.4. Michaelis constant (Km) under the optimal conditions is 6.34 × 10−3 M. Maximum enzyme activity is obtained at 40 °C, and the activation energy (ΔE) is 13,000 cal/mole, within the limits of optimum temperature. Inorganic phosphate inhibits competitively and Ki value is 3.45 × 10−3 M. Partial inhibition by fluoride is shown. Apparent effect of metallic ions also has been demonstrated.Comparison of these results with those reported in the literature for several other species of insects, as well as with those in certain mammalian systems, has been discussed.

Characterization and Subcellular Localization of Leucine Aminonaphthylamidase (LAN) in Rainbow Trout (Salmo gairdneri)

1975 ◽  
Vol 32 (8) ◽  
pp. 1289-1295 ◽  
Author(s):  
G. R. Bouck ◽  
P. W. Schneider Jr. ◽  
Janet Jacobson ◽  
R. C. Ball
Keyword(s):  
Enzyme Activity ◽  
Rainbow Trout ◽  
Reaction Time ◽  
Blood Plasma ◽  
Substrate Concentration ◽  
Room Temperature ◽  
Diagnostic Value ◽  
Inhibitory Effect ◽  
Salmo Gairdneri ◽  
Body Temperatures

LAN analyses appear to have diagnostic value in fish pathobiology and studies were undertaken to determine optima for substrate concentration, pH, reaction time, temperature, and buffer ions. Citrate ion did not inhibit LAN at anticoagulant levels, but cyanide, pyrophosphate, and EDTA had an inhibitory effect. Storage of samples at —10 and 1 C resulted in small but significant reductions of LAN activity, while at room temperature enzyme activity was rapidly lost. LAN activity was distributed among liver fractions as follows: microsomes, 12%; mitochondria, 9%; cellular sap, 37%; other, 50%. Three isozymes of LAN were found. Blood plasma contained significant amounts of LAN activity which was significantly higher in cold- than in warm-acclimated fish. However, these LAN levels were comparable when their activity was extrapolated to body temperatures.

New fluorogenic substrates for the determination of post-proline endopeptidase activity

1990 ◽  
Vol 55 (4) ◽  
pp. 1112-1118 ◽  
Author(s):  
Chryssa Tzougraki ◽  
George Kokotos ◽  
Hana P. Mašková ◽  
Eva Anzenbacherová ◽  
Tomislav Barth
Keyword(s):  
Enzyme Activity ◽  
Organic Solvent ◽  
Fluorogenic Substrate ◽  
Michaelis Constant ◽  
Fluorogenic Substrates ◽  
Endopeptidase Activity ◽  
Optimum Ph ◽  
Adverse Influence

A new fluorogenic substrate for determination of the activity of post-proline endopeptidase (EC 3.4.21.26), Z-Cys(Bzl)-Pro-NH-Meq has been synthesized. Affinity of this substrate to the enzyme was significantly higher than that of the hitherto employed substrates. The Michaelis constant of the post-proline endopeptidase for Z-Cys(Bzl)-Pro-NH-Meq was at the optimum pH (7.0) 1.05 10-6 mol l-1. The concentration of dimethylsulfoxide used for the solubilization of Z-Cys(Bzl)-Pro-NH-Meq (<0.4%) was outside the limits of adverse influence of the organic solvent on the enzyme activity. The fluorogenic substrate Z-Gly-Pro-NH-Meq was also synthesized for comparison (Km = 10.35 10-6 mol l-1 at pH 7.0).

scholarly journals PENGARUH EKSTRAK METANOL DAUN PEPAYA (Carica papaya L.) TERHADAP AKTIVITAS ENZIM LIPASE

KOVALEN ◽  
2017 ◽  
Vol 3 (3) ◽  
pp. 211
Author(s):  
Nurhaeni Nurhaeni ◽  
Ahmad Ridhay ◽  
Magfira Magfira
Keyword(s):  
Enzyme Activity ◽  
Lipase Activity ◽  
Incubation Time ◽  
Substrate Concentration ◽  
Goal Attainment ◽  
Carica Papaya ◽  
Methanol Extract ◽  
Ph Optimum ◽  
Lipase Enzyme ◽  
Optimum Ph

Has conducted research on the effects of methanol extract of leaves papaya (Carica papaya L.) Against Lipase Enzyme Activity. This study aimed to obtain information in a methanol extract inhibits lipase activity. The method used is Complete Random Design (RAL), with goal attainment is done by determining the incubation time lipase enzyme, pH optimum lipase enzyme, and maximum substrate concentration lipase enzyme. And determining the effect of the methanol extract to inhibit the lipase enzyme activity. The results showed that the best incubation time of lipase obtained by time of 120 minutes, the optimum pH 7 and the maximum substrate concentration of 4%. With the highest activity were obtained 16.94 mol /ml.menit, 13.33 mol / ml.menit, and 12.89 mol / ml.menit. The methanol extract of papaya leaves can inhibit the lipase enzyme activity the best concentration of 2% with the acquisition activity of 3.67 mol/ml.menit.Keyword: papaya, lipase, incubation time, optimum pH, substrate concentration.

The effect of low oxygen tension on the activity of aerobic dehydrogenases

1952 ◽  
Vol 140 (899) ◽  
pp. 230-243 ◽  
Keyword(s):  
Enzyme Activity ◽  
Amino Acid ◽  
Substrate Concentration ◽  
Substrate Oxidation ◽  
Acid Oxidase ◽  
Low Oxygen ◽  
Michaelis Constant ◽  
Amino Acid Oxidase ◽  
Low Oxygen Tension ◽  
Primary Substrate

The oxidation of D-alanine, hypoxanthine and glucose by D-amino-acid oxidase, xanthine oxidase and glucose oxidase (notatin) respectively has been studied at O 2 tensions varying from 1 to 100 %, mainly with a view to examining enzyme activity at an O 2 tension comparable to that obtaining in the animal body, i.e. < 10 % O 2 . It was found that ( a ) the rate of substrate oxidation decreases markedly at O 2 tensions < 20 % , i.e. the enzymes examined have a low O 2 affinity; ( b ) the substrate concentration giving half-maximal oxidation rate (= Michaelis constant, K m ) decreases with a lowering of the O 2 tension; ( c ) the rate of primary substrate oxidation at low O 2 tension in presence of catalase is higher than in presence of catalase and a secondary substrate which undergoes peroxidatic oxidation by catalase and H 2 O 2 . A possible mechanism underlying this effect, which involves the participation of catalase and H 2 O 2 in primary substrate oxidation at low O 2 tension, is suggested.

Alkaline phosphatase. I. Kinetics and inhibition by levamisole of purified isoenzymes from humans.

1976 ◽  
Vol 22 (7) ◽  
pp. 972-976 ◽  
Author(s):  
H Van Belle
Keyword(s):  
Alkaline Phosphatase ◽  
Substrate Concentration ◽  
Human Liver ◽  
Alkaline Phosphatases ◽  
Mechanism Of Inhibition ◽  
Optimum Ph ◽  
Alkaline Phosphatase Isoenzymes

Abstract I studied the kinetics and sensitivity toward inhibition by levamisole and R 8231 of the most important human alkaline phosphatase isoenzymes. N-Ethylaminoethanol proved superior to the now widely used diethanolamine buffer, especially for the enzymes from the intestine and placenta, behaving as an uncompetitive activator. The optimum pH largely depends on the substrate concentration. The addition of Mg2+ has no effect on the activities. The meaning of Km-values for alkaline phosphatases is questioned. Isoenzymes from human liver, bone, kidney, and spleen are strongly inhibited by levamisole or R 8231 at concentrations that barely affect the enzymes from intestine or placenta. The inhibition is stereospecific, uncompetitive, and not changed by Mg2+. Inhibition is counteracted by increasing concentrations of N-ethylaminoethanol. The mechanism of inhibition is suggested to be formation of a complex with the phosphoenzyme.

scholarly journals The apparent Km is a misleading kinetic indicator

1986 ◽  
Vol 239 (1) ◽  
pp. 175-178 ◽  
Author(s):  
I W Plesner
Keyword(s):  
Substrate Concentration ◽  
Kinetic Data ◽  
Substrate Binding ◽  
Enzymic Activity ◽  
Free Enzyme ◽  
Ligand Concentration ◽  
Double Reciprocal Plot ◽  
Michaelis Constant ◽  
Formal Framework ◽  
Enzyme Species

When information concerning whether or not a ligand interacts with the same enzyme species as do the substrates, the variation of the Michaelis constant Km (for each substrate) with ligand concentration is sometimes used as a diagnostic. It is shown that the Michaelis constant is of no particular value in this respect and may be misleading. Thus, depending on the mechanism, Km may vary with ligand concentration even though the ligand interacts with species far removed in the mechanism from the substrate-binding steps, and it may stay constant in cases where the ligand competes directly for the free enzyme. In contrast, the slope of a double-reciprocal plot of the kinetic data (= Km/Vmax.) (or, equivalently, the ordinate intercept of a Hanes plot A/v versus A, where A is the substrate concentration) independently of the particular mechanism involved uniquely signifies whether or not such interaction occurs. The results clearly indicate that, for purposes other than communicating the substrate concentration yielding control of the enzymic activity, usage of Km and its variation with ligand concentration should be avoided and interest instead focused on the slope, in accordance with the long-established rules of Cleland [Biochim. Biophys. Acta (1963) 67, 188-196], for which the present analysis provides the formal framework.

scholarly journals Partial purification and characterization of an endo-α-N-acetylgalactosaminidase from the culture medium of Streptomyces sp. OH-11242

1992 ◽  
Vol 288 (2) ◽  
pp. 475-482 ◽  
Author(s):  
I Ishii-Karakasa ◽  
H Iwase ◽  
K Hotta ◽  
Y Tanaka ◽  
S Omura
Keyword(s):  
Enzyme Activity ◽  
Culture Medium ◽  
Gel Filtration ◽  
Partial Purification ◽  
Gastric Mucus ◽  
Purification And Characterization ◽  
Streptomyces Sp ◽  
Optimum Ph ◽  
New Type

For the purification of a new type of endo-alpha-N-acetylgalactosaminidase from the culture medium of Streptomyces sp. OH-11242 (endo-GalNAc-ase-S) [Iwase, Ishii, Ishihara, Tanaka, Omura & Hotta (1988) Biochem. Biophys. Res. Commun. 151, 422-428], a method for assaying enzyme activity was established. Using purified pig gastric mucus glycoprotein (PGM) as the substrate, oligosaccharides liberated from PGM were pyridylaminated, and the reducing terminal sugars of oligosaccharides larger than Gal beta 1-3GalNAc were analysed by h.p.1.c. The crude enzyme of endo-GalNAc-ase-S was prepared as an 80% (w/v) ammonium sulphate precipitate from the concentrated culture medium. The enzyme was partially purified by gel chromatofocusing and subsequent DEAE-Toyopearl chromatography. Endo-enzyme activity eluted around pI 4.8 on a gel chromatofocusing column and eluted with 0.19-0.25 M-NaCl on a DEAE-Toyopearl column. In the enzyme fraction obtained, no exo-glycosidases or proteases could be detected. The molecular mass of the enzyme was estimated as 105 kDa by gel filtration, and the optimum pH was 5.5. Endo-GalNAc-ase-S hydrolysed the O-glycosidic linkage between GalNAc and Ser (Thr) in 3H-labelled and unlabelled asialofetuin, liberating both the disaccharide (Gal beta 1-3GalNAc) and the tetrasaccharide [Gal beta 1-3 (Gal beta 1-4GlcNAc beta 1-6)GalNAc]. When endo-alpha-N-acetylgalactosaminidase from Alcaligenes sp. (endo-GalNac-ase-A) was incubated with 3H-labelled and unlabelled asialofetuin, only the disaccharide (Gal beta 1-3GalNAc) was liberated.

Effect of temperature and pH on the production, activity, and stability of α-amylase from Bacillus subtilis V37

2021 ◽  
Vol 66 (1) ◽  
pp. 72-79
Author(s):  
Thuoc Doan Van ◽  
Hung Nguyen Phuc
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Animal Feed ◽  
Culture Conditions ◽  
Effect Of Temperature ◽  
Physical Parameters ◽  
Original Activity ◽  
Optimum Ph ◽  
Production Activity ◽  
Ph Range

The effect of physical parameters such as temperature and pH on the production, activity, and stability of α-amylase from Bacillus subtilis V37 was investigated. The results indicated that the optimum culture conditions for enzyme activity were pH 7.0 and 35 oC. The optimum pH and temperature for enzyme activity were 6.0 and 70 oC. The crude enzyme was found to be stable in the pH range of 5.0 to 7.0. The enzyme was stable for 1 h at a temperature from 30 to 80 oC; nearly 100% of enzyme activity remained at temperatures of 30 - 40 oC, and about 34% of original activity remained at a temperature of 80 oC. These features demonstrated that α-amylase from B. subtilis V37 can be applied in many areas such as the food, fermentation, and animal feed industries.

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