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1.
《The International journal of biochemistry》1990,22(6):601-605
- 1.1. Isoenzymes of d-lactate specific dehydrogenase from foot, mantle and hepatopancreas of Patella caerulea have been purified by Chromatographic techniques. d-lactate dehydrogenase (d-Ldh) from P. caerulea tissues was found to be tetrameric with a Mr of ca 140,000 as judged by gel filtration; subunit Mr of ca 37,000 was obtained from SDS-electrophoresis.
- 2.2. Kinetic studies suggest that P. caerulea foot and mantle d-Ldh is similar to vertebrate muscle-type l-Ldh; furthermore hepatopancreas d-LDH resembles vertebrate heart-type l-LDH since it has a higher affinity for d-lactate and is inhibited by pyruvate.
- 3.3. The results imply that the P. caerulead-Ldh isoenzymes may have distinct metabolic functions.
2.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(4):721-724
- 1.1. Activities of the three ammonia-forming enzymes, glutamate dehydrogenase, AMP deaminase and serine dehydrase (SerDH), were measured in tissues of gill, digestive diverticula, mantle and foot muscle of the brackish-water bivalve Corbicula japonica.
- 2.2. High levels of SerDH activity were detected in gill and digestive diverticula, while the activity levels of the other two enzymes were low.
- 3.3. The result suggests the significance of SerDH in amino acid degradation of this species.
3.
《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.
4.
《Comparative biochemistry and physiology. A, Comparative physiology》1986,83(3):503-505
- 1.1. The shell side of the mantle of Achatina fulica is several millivolts positive to the blood side in vitro.
- 2.2. The electrical potential does not depend on Na+, Ca2+, Mg2+, K+ or HCO3− but requires the presence of chloride on the shell side.
- 3.3. The potential difference and short-circuit current ranged from 3.0 to 30.0 mV and 15.0 to 75 μA/cm2 with averages at 10m V and 50 μA/cm2 respectively.
- 4.4. The electrical gradient is reduced by 2,4-dinitrophenol, thiocyanate and furosemide but not by ouabain, CO2 or acetozolamide.
- 5.5. It is suggested that the nature and mechanism of electrogenesis in Achatina parallels that of the Helix mantle.
5.
《Comparative biochemistry and physiology. C: Comparative pharmacology》1988,89(2):399-402
- 1.1. Optimum in vitro conditions, and kinetics of the enzyme catechol-O-methyltransferase from the brain of the male African catfish were studied.
- 2.2. A saturated level for S-adenosylmethionine, as methyldonor, and magnesium as cofactor was reached at 5 μM and 10 mM, respectively.
- 3.3. The addition of ascorbic acid, as an antioxidant, and tranylcypromine, as a MAO inhibitor, was not necessary, during incubations with fore-brain homogenates.
- 4.4. Kinetic analysis of the methylation of catecholestrone, catecholestradiol and dopamine showed Km values of 1.2, 0.6 and 0.5 μM, respectively.
- 5.5. The affinity of the catecholsubstrates for the enzyme catechol-O-methyltransferase is much higher in the brain of the African catfish than in tissues of mammals.
6.
- 1.1. The palmitic acid fate as substrate for the synthesis of either glycerides or other fatty acids was studied in vivo and in the microsomal fraction from hepatopancreas of Macrobrachium borellii.
- 2.2. Most of the palmitic acid administered in vivo circulated to the hepatopancreas, being incorporated mainly in the triacylglycerol (TG) fraction.
- 3.3. Palmitic acid transformations into palmitoleic, stearic and oleic acids were observed in the hepatopancreas.
- 4.4. The in vitro biosynthesis of TG in hepatopancreas was more active than in other tissues. In the microsomal fraction, palmitic acid was also incorporated mainly in TG, and followed the α-glycerophosphate pathway.
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.
《The International journal of biochemistry》1990,22(11):1333-1339
- 1.1. The reactivities of lysine residues of recombinant rat guanidinoacetate methyltransferase were determined by trace labeling with acetic anhydride.
- 2.2. Lys-113 and -160 were weakly reactive and Lys-178 and -234 were unreactive toward the reagent. The six lysines (Lys-38, -83, -104, -108, -152 and -180) showed moderate reactivities. The N-terminal amino group was very reactive.
- 3.3. S-Adenosylmethionine did not alter the reactivities of lysines significantly, but the reactivity of Lys-38 was substantially reduced in the presence of S-adenosylmethionine and guanidinoacetate.
9.
《The International journal of biochemistry》1984,16(6):623-628
- 1.1. 3-hydroxykynureninase in human liver was present in cytosol and mitoehondria.
- 2.2. The cytosolic enzyme and mitochondrial enzyme had the same physiological and enzymic properties.
- 3.3. The enzyme had a mol. wt of 130,000 by gel filtration and isoelectric point of pH 5.9.
- 4.4. The enzyme was active for 3-hydroxykynurenine and kynurenine, and its activity ratio was 15:1. The apparent Km values of the enzyme were 7.7 × 10−5M for 3-hydroxykynurenine, 1.0×10−3M for kynurenine and 2.5 × 10−6M for pyridoxal 5'-phosphate with 3-hydroxykynurenine.
- 5.5. Some other properties of purified enzymes are described.
10.
《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−.
11.
《The International journal of biochemistry》1993,25(12):1963-1968
- 1.1. The native rat-kidney cortex Fructose-1,6-BPase is differentially regulated by Mg2+ and Mn2+.
- 2.2. Mg2+ binding to the enzyme is hyperbolic and large concentrations of the cation are non-inhibitory.
- 3.3. Mn2+ produces a 10-fold rise in Vmax higher than Mg2+. [Mn2+]0.5 is much larger than [Mg2+]0.5. At elevated [Mn2+] inhibition is observed.
- 4.4. Mg2+ and Mn2+ produce antagonistic effects on the inhibition of the enzyme by high substrate.
- 5.5. Fru-2,6-P2 inhibits the enzyme by rising the S0.5 and favouring a sigmoidal kinetics.
- 6.6. The inhibition by Fru-2,6-P2 is released by Mg2+ and more powerfully by Mn2+ increasing the I0.5.
12.
《Comparative biochemistry and physiology. A, Comparative physiology》1990,95(1):145-147
- 1.1. In the contents of the oesophagus and stomach, one form of acid phosphatase is found. Its electrophoretic mobility is identical to that of the multiple form 3 of acid phosphatase from the hepatopancreas.
- 2.2. The enzyme is not stimulated by divalent cations. It is inhibited by molybdate, Cu2+, Hg2+. F− and tartrate L+.
- 3.3. The optimum pH of the enzyme is 4.5. The Km for paranitrophenylphosphate as substrate amounts to 0.25 mM. The enzyme is stable at a temperature of up to 55°C.
13.
《Comparative biochemistry and physiology. B, Comparative biochemistry》1993,104(4):925-932
- 1.1. In order to assign a meaningful role to the phosphorolytic pathway in Mytilus glycogen metabolism the kinetic mechanism of phosphorylase b, and its allosteric control, were studied.
- 2.2. The kinetic parameters of phosphorylase b from the mussel Mytilus galloprovincialis were determined. Michaelis constants (Km or S0.5) were in the range of 0.32–2.49 mg/ml for glycogen, 7–16 mM for Pi and 114–423 μM for AMP. In the direction of glycogen synthesis, the Km value for glucose-1-P was approximately 180 mM.
- 3.3. The enzyme displayed homotropic co-operativity towards the binding of co-substrate and AMP (Hill coefficients of 2 and 1.4, respectively) and heterotropic co-operativity between substrates and AMP.
- 4.4. The concentration of glycogen in the Mytilus mantle is between 38- and 125-fold higher than the apparent Km of phosphorylase b; the concentration of AMP varies throughout the year from 10 to 175 μM, up to a value close to the apparent Km for the effector.
- 5.5. The apparent Km for Pi is close to the concentration found in the mantle. This ligand showed more important regulatory effects than the effector AMP.
14.
《The International journal of biochemistry》1986,18(7):589-594
- 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
- 2.2. Optimal pH for the activity was approximately 7.
- 3.3. The activity was stimulated by Mg2+.
- 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN3, NaVO3, or PCMB but not inhibited by ouabain.
15.
《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.
16.
《The International journal of biochemistry》1984,16(8):875-881
- 1.1. Rat liver cytoplasmic acetyl-CoA synthetase was partially purified (purification factor = 23, yield = 30%).
- 2.2. The apparent Kms for acetate, coenzyme A, ATP and MgCl2 were determined and found to be 52.5 μM, 50.5 μM, 570 μM and 1.5 mM, respectively.
- 3.3. The partially-purified enzyme showed a low affinity for short-chain carbon substrates other than acetate.
- 4.4. The properties of the partially-purified enzyme were compared with those of enzymes from other sources.
17.
《The International journal of biochemistry》1985,17(3):341-345
- 1.1. A new tetralysine endopeptidase from Escherichia coli AJ005 has been purified about 135-fold.
- 2.2. The peptidase seems to be specific to tetralysine among lysine homopolymers.
- 3.3. The optimal pH was about 7.5
- 4.4. The activity was inhibited by KCN but not inhibited by soybean trypsin inhibitor.
- 5.5. The apparent Km value was 2.5 × 1O−3 M for tetralysine.
18.
《The International journal of biochemistry》1983,15(3):329-336
- 1.1. The interaction of insulin with purified brush-border membranes from rat kidney was studied with the use of [125I]insulin.
- 2.2. The specific binding of insulin by brush-borders could be demonstrated, and was time- and temperature-dependent.
- 3.3. [125I]insulin was displaced by unlabelled insulin. A1-B29 dodecoyl insulin and insulin A- and B-chains in proportion to their relative bioactivity.
- 4.4. Brush-border membranes showed high insulin-degrading activity with an apparent Km of 2.2 μM.
- 5.5. A number of proteinase inhibitors were effective in inhibiting insulin degradation but the greatest degree of inhibition was achieved by the use of thiol-blocking reagents.
- 6.6. No evidence was obtained for the involvement of the enzyme glutathione-insulin transhydrogenase.
19.
《The International journal of biochemistry》1985,17(2):253-257
- 1.1. Pyruvate kinase from mycelium of Phycomyces blakesleeanus NRRL 1555(−) has been partially purified and some kinetic properties has been investigated at pH 7.5.
- 2.2. Positive homotropic interactions were observed with phosphoenolpyruvate and Mg2+, showing Hill coefficient values of 2.8 and 2.5, respectively, whereas hyperbolic kinetics are found when ADP was the variable substrate.
- 3.3. Fructose 1,6-bisphosphate acts as a heterotropic allosteric activator, markedly decreasing the S0.5 value for phosphoenolpyruvate saturation curve from a sigmoidal to a hyperbolic form.
- 4.4. ATP inhibits pyruvate kinase from mycelium of Phycomyces blakesleeanus. ATP appears to be a non-competitive inhibitor with respect PEP and competitive inhibitor with respect ADP.
20.
《Comparative biochemistry and physiology. A, Comparative physiology》1991,98(3):595-598
- 1.1. Proteolytic, lipolytic, amylolytic and cellulolytic activities were studied in adults of the phytophagous beetle, Hydromedion sparsutum, indigenous to the sub-Antarctic island of South Georgia.
- 2.2. Gastric enzyme activities were measured at experimental temperatures of 5–40°C and results were compared with those obtained from two thermophilic insects, Gryllus bimaculatus and Tenebrio molitor.
- 3.3. Protease and lipase activities in Hydromedion were 10–15 times lower than in Gryllus and Tenebrio.
- 4.4. In the temperature range of 5–15°C, α-amylase activity from Hydromedion was only slightly lower than that from Gryllus.
- 5.5. Hydromedion gut homogenates exhibited a distinct cellulolytic activity, even at a low temperature of 5°C.
- 6.6. Cellulolytic activity in the digestive tract of Hydromedion was confirmed by the evolution of 14CO2 after consumption of labelled cellulose.
- 7.7. The thermal properties of digestive enzymes agree well with the role of Hydromedion as primary decomposer in its ecosystem.