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1.
《The International journal of biochemistry》1991,23(12):1445-1451
- 1.1. An alkaline p-nitrophenylphosphate phosphatase has been purified 440-fold from extracts of Hatobacterium halobium.
- 2.2. The enzyme has an apparent molecular weight of 24,000.
- 3.3. A Km value for p-nitrophenylphosphate of 1.12mM has been found under optimal conditions.
- 4.4. The enzyme is selectively activated and stabilized by Mn2+.
- 5.5. It requires high salt concentrations for stability and maximum activity.
- 6.6. It displays an unusual restricted substrate specificity of 25 phosphate esters tested, only phosphotyrosine and casein were hydrolysed besides p-nitrophenylphosphate.
2.
《The International journal of biochemistry》1992,24(10):1657-1660
- 1.1. A thermostable orthophosphoric monoester phosphohydrolase (EC 3.1.3.1) from Thermus sp strain Rt41A has been purified 400-fold to give a specific activity of 25 U/mg at 60°C in IM diethanolamine (pH 11.1).
- 2.2. The enzyme has a Mr of 160,000 and is trimeric.
- 3.3. The half-life of the enzyme is 5 min at 85°C.
- 4.4. The enzyme has a wide specificity for a number of phosphate monoesters.
- 5.5. The Hm of the enzyme is pH dependent, so the pH optimum of the enzyme is affected by the substrate concentration.
- 6.6. The enzyme is inhibited 50% by 20 mM Ca2+ or Mg2+.
- 7.7. The Ki for phosphate, EDTA-di sodium salt and arsenate (in 1 M diethanolamine, pH 11.1) is approx 1.2, 1.6 and 4mM respectively.
- 8.8. Urea (200 mM) is not inhibitory.
3.
《The International journal of biochemistry》1984,16(1):117-120
- 1.1. The specific activity of GMP synthetase was measured in several human tissues and found to be highest in cultured skin fibroblasts, followed by bone marrow, leukocytes, erythrocytes. placenta, and liver.
- 2.2. The enzyme from fibroblasts was purified approximately 50-fold by ammonium sulfate fractionation and gel filtration.
- 3.3. The Km values were determined to be 4.9μM for XMP, 270μM for ATP. and 340 μM for glutamine.
- 4.4. Ammonium sulfate could replace glutamine as the amino donor but was much less efficient.
- 5.5. The enzyme was specific for ATP as the energy source.
- 6.6. Unlike the calf thymus enzyme, the human enzyme has no requirement for a reduced sulfhydryl compound.
- 7.7. Human GMP synthetase is inhibited by ATP, dATP, azaserine, and hydroxylamine.
4.
《The International journal of biochemistry》1984,16(12):1217-1221
- 1.1. Primate liver lysosomal acid DNase is an endonucleolytic enzyme.
- 2.2. The enzyme has both 3'- and 5'-nucleotidohydrolase activities.
- 3.3. The oligonucleotides produced by DNase are polymers mainly about 30 mononucleotides long.
- 4.4. The Arrhenius plot shows a discontinuity with a transition temperature at 47°C, with an activation energy of 107 kJ/mol below and 67 kJ/mol above this temperature.
- 5.5. The activation enthalpy is 104kJ/mol and the entropy −0.498 kJ/mol/K.
- 6.6. The enzyme is subject to substrate inhibition and the Km value is 159 × 10−3mM DNA-P.
5.
《The International journal of biochemistry》1993,25(9):1325-1330
- 1.1. A lipoxygenase activity was purified from Thermoactinomyces vulgaris and some of its properties were characterized.
- 2.2. The enzyme showed a temperature activity range of 40–55°C with still significant activity over 60°C.
- 3.3. The pH of activity on linoleic acid had a broad range with an optimum at pH 6.0 and a weaker one at pH 11.0.
- 4.4. On arachidonic acid the pattern was narrow bell-shaped with an optimum at pH 6.5.
- 5.5. The purified lipoxygenase from Th. vulgaris showed an apparent Km of 1 mM and Vmax of 0.84 μmol diene/min/mg protein.
- 6.6. It was inhibited by the oxidation products, 9-HPOD and 13-HPOD.
- 7.7. A 160,000 Da molecular weight of the enzyme was determined by molecular filtration. Methionine, tyrosine, tryptophan and cysteine are apparently involved in its activity.
6.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1987,86(4):1151-1155
- 1.1. Biliverdin reductase from the liver of eel, Anguilla japonica was characterized and purified with a novel enzymatic staining method on polyacrylamide electrophoretic gel.
- 2.2. This enzyme could use both NADPH and NADH as coenzyme. The Km of NADPH was 5.2 μM, while that of NADH was 5.50 μM.
- 3.3. The optimum reaction pH for using HADPH as coenzyme was 5.3. That for NADH was 6.1. The optimum reaction temperature is 37°C.
- 4.4. When NADPH was used as coenzyme, the Km of biliverdin was 0.6 μM. When NADH was used as coenzyme, the Km of biliverdin was 7.0 μM.
- 5.5. The activity of the enzyme was inhibited by the concentration of biliverdin. Also, the potency of the enzyme was much less than that of the analogous enzyme isolated from mammals.
- 6.6. This is a fairly stable enzyme with a mol. wt around 67,000. Its estimated pI was pH 3.5–4.0.
- 7.7. This is the first time biliverdin reductase has been isolated and characterized from a vertebrate other than mammals. The property of it is quite different from that of mammals.
7.
《The International journal of biochemistry》1991,23(10):991-995
- 1.1. Purified ostrich (Struthio camelus) liver fructose-1,6-bisphosphatase exhibited an absolute requirement for Mg2+.
- 2.2. The enzyme catalyzed the hydrolysis of fructose-1,6-bisphosphate, sedoheptulose-l,7-bisphosphate and ribulose-l,5-bisphosphate.
- 3.3. S0.5 for substrate was 1.4 μM.
- 4.4. AMP was a potent non-competitive inhibitor with respect to substrate (Ki of 25 μM).
- 5.5. Fructose-2,6-bisphosphate was a potent competitive inhibitor of the enzyme (Ki of 4.8 μM).
8.
《Comparative Biochemistry and Physiology》1982,17(4):1079-1087
- 1.The trytophan pyrrolase activity of central fat bodies of S. gregoria hoppera was studied.
- 2.The enzyme system appears to be similar to that of mammalian liver.
- 3.The enzyme was localized only in central fat bodies.
- 4.Extracts of other body parts can mimic an enzyme activity because of a degradation of ommochromes in the enzyme test.
9.
《The International journal of biochemistry》1981,13(5):591-602
- 1.1. A choriolytic enzyme was isolated from the hatching medium of the pike, Esox lucius.
- 2.2. The enzyme is defined as hatching enzyme.
- 3.3. The molecular weight of the enzyme is 24,000.
- 4.4. The enzyme is a glycoprotein containing 2% carbohydrate.
- 5.5. Its isoelectric point is 6.5.
- 6.6. The pH optimum is around pH 8.
- 7.7. The enzyme molecule contains two disulfide bonds but no free cysteine.
- 8.8. Inhibitor studies and metal analysis show that the enzyme is a zinc-metalloprotease.
10.
《The International journal of biochemistry》1987,19(9):831-835
- 1.1. Malic enzyme purified from the fruit tissue of Mangifera indica was irradiated in dilute solution and the effect of γ-irradiation was investigated.
- 2.2. The activity of the enzyme decreased exponentially as a function of the applied dose under all conditions investigated. The inactivation yield (Go-value) in neutral solution and in air was 0.069.
- 3.3. The role of the radicals produced by water radiolysis in the inactivation of the enzyme was investigated by using different gas atmospheres and selective free radical-anions. The hydrogen atom and the hydrated electron (reducing species) were found to be important in the enzyme inactivation; as well as the possible destruction of cysteine and tryptophan residues.
- 4.4. The irradiated enzyme appears to adopt a more compact conformation as reflected in a slightly lower Mr, Stokes-radius and diffusion coefficient.
- 5.5. γ-Radiation does not lead to any heterogeneity in the charge and size properties of the enzyme and the pI and the Mr of the subunits were unaffected.
- 6.6. Some differences in the amino acid composition of the non-irradiated and irradiated enzyme were observed but specific amino acid residues were not preferentially destroyed.
- 7.7. These changes were also reflected in the ultraviolet spectrum of the enzyme which shifted to lower values.
- 8.8. The major cause of inactivation seem to be a change in conformation caused by chemical modification of amino acid side chains.
11.
《The International journal of biochemistry》1989,21(8):909-912
- 1.1. A third form (D3) of cyclic nucleotide phosphodiesterase from Rhizobiumfrediiv/as detected and characterized for the first time.
- 2.2. The enzyme could hydrolyse both cyclic AMP and cyclic GMP with apparent Km for cyclic AMP of approx. 0.2 μM.
- 3.3. D3 cyclic nucleotide phosphodiesterase had a pH optimum of about 6.0 when hydrolysing cyclic AMP.
- 4.4. The enzyme lost almost all its activity when heated to 60°C for 20 min.
- 5.5. Gel filtration with Sephadex G-100 gave a mol. wt of approx. 42.5 kD for the native enzyme.
12.
《The International journal of biochemistry》1985,17(10):1085-1089
- 1.1. Hydroxypyruvate reductase has been purified 193-fold from Lemna minor L. by affinity chromatography on Blue Sepharose.
- 2.2. The enzyme has activity over a broad pH range (optimum pH 6), a Km hydroxypyruvate of 59 μ M and Km NADH of 12μM.
- 3.3. Crude extracts of Lemna exhibit substrate inhibition of activity above 1 mM hydroxypyruvate, a property which is lost on purification.
- 4.4. Oxaloacetate inhibits purified preparations of the enzyme and a possible role for such regulation in vivo is discussed.
13.
《The International journal of biochemistry》1984,16(12):1373-1378
- 1.1. Glycollate oxidase has been purified to apparent homogeneity from Lemna minor L. grown on medium containing 7mM NO−3.
- 2.2. The enzyme is a highly basic protein with a sub-unit molecular weight of 42,000 and a holoprotein molecular weight of 250,000.
- 3.3. The Lemna enzyme is a flavoprotein with a broad specificity for straight chain α-hydroxy acids, the preferred substrate being glycollate.
- 4.4. It is also competitively inhibited by oxalate and phenyllactate.
- 5.5. A comparison is drawn between the physical properties of glycollate oxidase from a number of higher plants and the degree of sub-unit aggregation in the resulting protomers.
14.
《Comparative biochemistry and physiology. A, Comparative physiology》1986,83(3):489-493
- 1.1. Fundamental chitin digestion characteristics of Crassostrea virginica crystalline style were investigated.
- 2.2. Optimum temperature and pH were 34°C and 4.8. respectively.
- 3.3. The colloidal regenerated chitin (0.56mol/0.5 ml: GlcNAc equivalents) was saturating under all enzyme levels encountered.
- 4.4. There was no evidence of end product inhibition, even after 100 hr incubation.
- 5.5. Calculated Km for the chitinase complex was 1.19mM when determined using a 30 min assay, but was only 0.70 mM when determined using a 4.6 hr assay.
- 6.6. Both Km values are lower than reported for similar assays in other molluscs and for most bacteria.
- 7.7. Effect of substrate preparation on the kinetics are discussed.
- 8.8. Eight peaks of chitinase activity were resolved by DEAE-Fractogel ion exchange chromatography.
15.
《The International journal of biochemistry》1984,16(11):1099-1106
- 1.1. NAD(P)H dehydrogenase from rabbit liver was purified to electrophoretic homogeneity using a procedure also found applicable for the rat liver enzyme.
- 2.2. Rabbit and rat liver enzymes showed different behaviour in isoelectric focusing and different Km values and turnover numbers.
- 3.3. Both enzymes were inhibited to similar extents by warfarin.
- 4.4. The rabbit enzyme is composed of two subunits of mol. wt 27,000 and contained 1 FAD group per subunit.
- 5.5. Some absorption and circular dichroism properties of the rat enzyme are shown.
16.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1993,104(3):681-684
- 1.1. Elastase has been purified from the hepatopancreas of the king crab (Paralithodes camtschatica). Specific activity of the enzyme measured toward Suc-(Ala)3-pNA and Boc-(Ala)3-pNA was 926 and 3700 mUnits per mg of protein, respectively.
- 2.2. The enzyme is an anion protein (pI 4.5) with an approximate mol.wt of 28.5 kDa.
- 3.3. The enzyme exhibited a bell-shaped pH-dependence for the hydrolysis of Suc-(Ala)3-pNA with a maximum at 8–8.5. Under these conditions the values of Km and kcat of the crab elastase are 4 mM and 4.75 s−1, respectively.
- 4.4. The serine elastase is effectively inhibited by elastinal and diisopropylfluorophosphate.
- 5.5. It is shown that some salts except HgCl2 activate the protease. In the presence of HgCl2 with concentrations of 10 mM and higher, the crab elastase is inactive. SDS and Triton X-100 have no any effect on the activity of crab elastase.
17.
《The International journal of biochemistry》1989,21(7):783-789
- 1.1. Kinetic constant values of the reaction catalyzed by bass liver glucose 6-phosphate dehydrogenase show to be modified between 10 and 40°C.
- 2.2. The Arrhenius plot between 10 and 50°C shows two slopes with different activation energies.
- 3.3. These results suggest a regulation of this enzyme by environmental temperature.
- 4.4. Kinetics of ATP inhibition were examined between pH 6.2 and 7.8: patterns and Ki values obtained are affected by the pH variation.
- 5.5. NADH is an effective inhibitor of bass glucose 6-phosphate dehydrogenase but this enzyme does not show NAD-linked activity.
- 6.6. Kinetics of pyridoxal 5′-phosphate inhibition have indicated the presence of a lysine in the catalytic site for NADP+.
18.
《The International journal of biochemistry》1993,25(6):879-884
- 1.1. Phospholipase A2 was isolated from Agkistrodon bilineatus venom by Sephadex G-75 and CM-Cellulose column chromatographies.
- 2.2. The purified phospholipase A2-I gave a single band on disc polyacrylamide gel electrophoresis, isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis.
- 3.3. The enzyme preparation had a molecular weight of 14,000, isoelectric point of pH 8.77 and possessed 123 amino acid residues.
- 4.4. The purified phospholipase A2 possessed lethal, indirect hemolytic and anticoagulant activities.
- 5.5. The enzyme hydrolyzed the phospholipids phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl inositol (PI) and phosphatidyl serine (PS).
- 6.6. The concentration of mouse diaphragm was inhibited and the contraction of guinea pig left atrium was increased by phospholipase A2-I.
- 7.7. Phospholipase A2 activity of this preparation was inhibited by ethylenediamine tetraacetic acid, p-bromo phenacyl bromide, n-bromo succinimide or dithiothreitol, but not by diisopropyl fluorophosphate or benzamidine.
19.
《The International journal of biochemistry》1981,13(7):865-869
- 1.1. Sedimentation velocity and sedimentation equilibrium studies of bovine heart AMP-deaminase were performed. Molecular weights of the native enzyme and subunit were determined as 161,000 and 43,000 dallons respectively.
- 2.2. The kinetic data indicate that in the presence of 100 mM KCl the enzyme may be active as a dimer.
- 3.3. The influence of temperature on the enzyme kinetics was investigated, from which activation energy (Ea and the heat of enzyme-substrate complex formation (ΔHs) were calculated.
- 4.4. It is suggested that an equilibrium may exist between a dimeric and tetrameric form of AMP-deaminase in the heart.
20.
《The International journal of biochemistry》1987,19(10):973-980
- 1.1. The purified enzyme hydrolyzes the linear l-lysinamide and the cycle amide of l-lysine—l-α-amino-ϵ-caprolactam.
- 2.2. The apparent relative molecular mass is 180,000. The enzyme consists of four subunits and the molecular mass of a single subunit was found to be 47,000.
- 3.3. The coefficient of molecular sedimentation equals 8.3 S, the isoelectric point was determined to be pH 4.3
- 4.4. The enzyme is not a glycoprotein. p-Mercuribenzoate binds 10 SH-groups of the native enzyme molecule and 20 SH-groups in the presence of 0.7% SDS.
- 5.5. pH- optimum for the hydrolysis of l-lysine amides was observed to be 7.5–7.7. The enzyme is strictly dependent on Mn2+ and Mg2+.
- 6.6. The kinetic parameters for the hydrolysis of l-lysinamide where Km = 3.8 mM and kcat = 3000 sec−1 For the hydrolysis of cyclic L-lysinamide Km = 4.8 mM and kcat = 2600 sec−.