scholarly journals The reaction of a histidine residue in glutamate dehydrogenase with diethyl pyrocarbonate

1973 ◽  
Vol 133 (1) ◽  
pp. 183-187 ◽  
Author(s):  
Robert B. Wallis ◽  
J. John Holbrook
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Steady State ◽  
Glutamate Dehydrogenase ◽  
Specific Activity ◽  
Histidine Residue ◽  
Apparent Change ◽  
Diethyl Pyrocarbonate ◽  
Polypeptide Chains ◽  
Rate Limiting

1. One mol of diethyl pyrocarbonate will react with one mol of glutamate dehydrogenase polypeptide chains to form one mol of N1-carbethoxyhistidine. Reaction is prevented by NADH. 2. The 1:1 complex has an increased specific activity (1.4–2.0-fold). 3. The reason for the activation is discussed. The results are not consistent with NADH dissociation from the enzyme–glutamate–NADH complex being rate-limiting in the steady state measured. 4. The effects of modification on the properties of the enzyme were investigated. The effects of GTP and NAD+ on the enzyme activity are unaltered by activation. NADH binding is unaltered and there is no apparent change in the molecular weight. However, the activated enzyme can still be further activated by ADP. Ks for ADP is decreased fivefold.

scholarly journals Inactivation of the endogenous argininosuccinate lyase activity of duck δ-crystallin by modification of an essential histidine residue with diethyl pyrocarbonate

1993 ◽  
Vol 293 (2) ◽  
pp. 537-544 ◽  
Author(s):  
H J Lee ◽  
S H Chiou ◽  
G G Chang
Keyword(s):  
Enzyme Activity ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Histidine Residue ◽  
Argininosuccinate Lyase ◽  
First Order ◽  
Diethyl Pyrocarbonate ◽  
Order Rate ◽  
Lyase Activity ◽  
Pseudo First Order

The argininosuccinate lyase activity of duck delta-crystallin was inactivated by diethyl pyrocarbonate at 0 degrees C and pH 7.5. The inactivation followed pseudo-first-order kinetics after appropriate correction for the decomposition of the reagent during the modification period. The plot of the observed pseudo-first-order rate constant versus diethyl pyrocarbonate concentration in the range of 0.17-1.7 mM was linear and went through the origin with a second-order rate constant of 1.45 +/- 0.1 M-1.s-1. The double-logarithmic plot was also linear, with slope of 1.13, which suggested a 1:1 stoichiometry for the reaction between diethyl pyrocarbonate and delta-crystallin. L-Arginine, L-norvaline or L-citrulline protected the argininosuccinate lyase activity of delta-crystallin from diethyl pyrocarbonate inactivation. The dissociation constants for the delta-crystallin-L-arginine and delta-crystallin-L-citrulline binary complexes, determined by the protection experiments, were 4.2 +/- 0.2 and 0.12 +/- 0.04 mM respectively. Fumarate alone had no protective effect. However, fumarate plus L-arginine gave synergistic protection with a ligand binding interacting factor of 0.12 +/- 0.02. The double-protection data conformed to a random Uni Bi kinetic mechanism. Fluorescence-quenching studies indicated that the modified delta-crystallin had minimum, if any, conformational changes as compared with the native delta-crystallin. Inactivation of the enzyme activity was accompanied by an increasing absorbance at 240 nm of the protein. The absorption near 280 nm did not change. Treatment of the modified protein with hydroxylamine regenerated the enzyme activity to the original level. These results strongly indicated the modification of an essential histidine residue. Calculation from the 240 nm absorption changes indicated that only one histidine residue per subunit was modified by the reagent. This super-active histidine residue has a pKa value of approximately 6.8 and acts as a general acid-base catalyst in the enzyme reaction mechanism. Our experimental data are compatible with an E1cB mechanism [Raushel (1984) Arch. Biochem. Biophys. 232, 520-525] for the argininosuccinate lyase with the essential histidine residue close to the arginine-binding domain of delta-crystallin. L-Citrulline, after binding to this domain, might form an extra hydrogen bond with the essential histidine residue.

scholarly journals Intracellular enzymes of collagen biosynthesis in rat liver as a function of age and in hepatic injury induced by dimethylnitrosamine. Purification of rat prolyl hydroxylase and comparison of changes in prolyl hydroxylase activity with changes in immunoreactive prolyl hydroxylase

1976 ◽  
Vol 158 (2) ◽  
pp. 369-376 ◽  
Author(s):  
J Risteli ◽  
L Tuderman ◽  
K I Kivirikko
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Hepatic Injury ◽  
Specific Activity ◽  
Prolyl Hydroxylase ◽  
Newborn Rats ◽  
Hydroxylase Activity ◽  
Immunoreactive Protein ◽  
Molecular Weights ◽  
Polypeptide Chains

Prolyl hydroxylase was purified from newborn rats by affinity chromatography using poly(L-proline), and antiserum to the enzyme was prepared in rabbits. The rat prolyl hydroxylase was similar to the chick and human enzymes with respect to specific activity, molecular weight and molecular weights of the polypeptide chains. The activity of prolyl hydroxylase and the content of immunoreactive enzyme were measured in rat liver as a function of age in experimental hepatic injury. Active prolyl hydroxylase comprised about 13.2% of the total immunoreactive protein in the liver of newborn rats and the value decreased to about 3.6% at the age of 420 days. This decrease was due to a decrease in the enzyme activity, whereas only minor changes were found in the content of the immunoreactive protein. In hepatic injury, a significant increase was found in the ratio of active enzyme to total immunoreactive protein, owing to an increase in the enzyme activity. The data indicate that prolyl hydroxylase activity in rat liver is controlled in part by a mechanism which does not involve changes in the content of the total immunoreactive protein.

INFLUENCE OF ANDROGENS ON THE WEIGHTS OF THE MALE ACCESSORY REPRODUCTIVE ORGANS AND ON THE ACTIVITIES OF MITOCHONDRIAL ENZYMES IN THE EPIDIDYMIS OF THE RAT

1979 ◽  
Vol 82 (2) ◽  
pp. 293-303 ◽  
Author(s):  
D. E. BROOKS
Keyword(s):  
Enzyme Activity ◽  
Steady State ◽  
Specific Activity ◽  
Reproductive Organs ◽  
Maximum Activity ◽  
Rate Of Change ◽  
Mitochondrial Enzymes ◽  
Tissue Weight ◽  
Accessory Glands ◽  
Cauda Epididymidis

SUMMARY The influence of androgens on the male accessory glands of the rat was assessed in terms of changes in weight and of the specific activity of the mitochondrial enzymes, succinate dehydrogenase, glycerolphosphate dehydrogenase and pyruvate carboxylase, in the epididymis. In some instances, the activity of the cytoplasmic enzymes, hexokinase and phosphofructokinase, was also measured and the influence of androgens on these enzymes was found to be similar to that on the mitochondrial enzymes. After the administration of androgen to castrated rats the specific activity of enzymes reached a new steady state sooner than did epididymal weight. The time taken for the specific activity of the enzymes to reach a new steady state after the removal of androgen was variable, depending on the enzyme and the region of the epididymis. This time was generally longer, however, than the time taken for induction, and in the case of glycerolphosphate dehydrogenase, the decline of activity was slower in the cauda than in the caput. In castrated animals, about 100 times as much androgen was required to attain maximum tissue weight as was required to attain maximum enzyme activity. The epididymis, prostate and seminal vesicles responded similarly to androgen in terms of the dose–response pattern and the time taken for tissue weight to attain a new steady-state value, although the gain in weight of the epididymis relative to its weight in unstimulated control animals was less than the relative gain of the other accessory glands. Enzymes in the cauda epididymidis required lower amounts of androgen to elicit maximum activity than were required by those in the caput. The rate of change in the accessory glands in attaining new steady-state levels of tissue weight and enzyme activity was independent of the dose of androgen except during the first few days of hormone administration. Androgens were the most effective steroids in stimulating an increase of tissue weight and enzyme activity, although some changes were induced by oestradiol-3-benzoate and progesterone.

scholarly journals Modification of lactate oxidase with diethyl pyrocarbonate. Evidence for an active-site histidine residue

1977 ◽  
Vol 165 (2) ◽  
pp. 385-393 ◽  
Author(s):  
Choong Yee Soon ◽  
Maxwell G. Shepherd ◽  
Patrick A. Sullivan
Keyword(s):  
Enzyme Activity ◽  
Chemical Reduction ◽  
Enzyme Inactivation ◽  
Subunit Structure ◽  
Histidine Residue ◽  
Lactate Oxidase ◽  
Histidine Residues ◽  
Diethyl Pyrocarbonate ◽  
Competitive Inhibitors ◽  
Active Site Histidine

1. Diethyl pyrocarbonate inactivated l-lactate oxidase from Mycobacterium smegmatis. 2. Two histidine residues underwent ethoxycarbonylation when the enzyme was treated with sufficient reagent to abolish more than 90% of the enzyme activity, but analyses of the inactivation showed that the modification of one histidine residue was sufficient to cause the loss of enzyme activity. The rates of enzyme inactivation and histidine modification were the same. 3. Substrate and competitive inhibitors decreased the maximum extent of inactivation to a 50% loss of enzyme activity and modification was decreased from 1.9 to 0.75–1.2 histidine residues modified/molecule of FMN. 4. Treatment of the enzyme with diethyl [14C]pyrocarbonate (labelled in the carbonyl groups) confirmed that only histidine residues were modified under the conditions used and that deacylation of the ethoxycarbonylhistidine residues by hydroxylamine was concomitant with the removal of the14C label and the re-activation of the enzyme. 5. No evidence was found for modification of tryptophan, tyrosine or cysteine residues, and no difference was detected between the conformation and subunit structure of the modified and native enzyme. 6. Modification of the enzyme with diethyl pyrocarbonate did not alter the following properties: the binding of competitive inhibitors, bisulphite and substrate or the chemical reduction of the flavin group to the semiquinone or fully reduced states. The normal reduction of the flavin by lactate was, however, abolished.

scholarly journals Modification of uridine phosphorylase from Escherichia coli by diethyl pyrocarbonate. Evidence for a histidine residue in the active site of the enzyme

1990 ◽  
Vol 270 (2) ◽  
pp. 319-323 ◽  
Author(s):  
A K Drabikowska ◽  
G Woźniak
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Active Site ◽  
Order Rate Constant ◽  
Enzymic Activity ◽  
Histidine Residue ◽  
Uridine Phosphorylase ◽  
High Concentration ◽  
Histidine Residues ◽  
Diethyl Pyrocarbonate

Uridine phosphorylase from Escherichia coli is inactivated by diethyl pyrocarbonate at pH 7.1 and 10 degrees C with a second-order rate constant of 840 M-1.min-1. The rate of inactivation increases with pH, suggesting participation of an amino acid residue with pK 6.6. Hydroxylamine added to the inactivated enzyme restores the activity. Three histidine residues per enzyme subunit are modified by diethyl pyrocarbonate. Kinetic and statistical analyses of the residual enzymic activity, as well as the number of modified histidine residues, indicate that, among the three modifiable residues, only one is essential for enzyme activity. The reactivity of this histidine residue exceeded 10-fold the reactivity of the other two residues. Uridine, though at high concentration, protects the enzyme against inactivation and the very reactive histidine residue against modification. Thus it may be concluded that uridine phosphorylase contains only one histidine residue in each of its six subunits that is essential for enzyme activity.

scholarly journals PREPARATION, PURIFICATION AND PROPERTIES OF LIPASE FROM HEPATOPANCREAS OF TRA (PANGASIUS) CATFISH

2011 ◽  
Vol 14 (3) ◽  
pp. 5-11
Author(s):  
Thy Bao Vuong ◽  
Lam Bich Tran ◽  
Duan Luu
Keyword(s):  
Heavy Metals ◽  
Molecular Weight ◽  
Enzyme Activity ◽  
Crude Extract ◽  
Gel Electrophoresis ◽  
Specific Activity ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Purification And Properties ◽  
Temperature Optima

Lipase from the hepatopancreas of Tra (Pangasius) catfish was purified by ammonium sulfate fractionation, followed by ion-exhange chromatography on DEAE Cellulose and gel filtration Sephadex G-75. The preparation was homogeneous on polyacrylamide disc gel electrophoresis. The specific activity of the purified enzyme was 37.95 times higher than that of the crude extract. The enzyme showed a molecular weight of 57000 Da. The pH and temperature optima of purified lipase were 8 and 500C respectively. Enzyme activity was enhanced by Ca2+ but inhibited by heavy metals Zn2+, Cd2+, Mg2+.

Alterations in glutamate dehydrogenase of the brain of rats of various ages

1970 ◽  
Vol 48 (2) ◽  
pp. 203-206 ◽  
Author(s):  
Gyan Kaur ◽  
M. S. Kanungo
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activity ◽  
Glutamate Dehydrogenase ◽  
Nervous Tissue ◽  
Specific Activity ◽  
Old Rats ◽  
Total Dna ◽  
Regulatory Effects ◽  
The Brain ◽  
Inhibited Enzyme

The activity of glutamate dehydrogenase of the brain of 6-, 22-, 52-, and 96-week-old rats was determined. The specific activity, units per milligram DNA and units per organ, increased with growth and was highest at 22 weeks. This was probably due to a higher rate of protein synthesis during growth since the total DNA content did not change during this period. The activity declined in old age. Some biogenic amines, endogenous to nervous tissue and possibly having neurotransmitter functions, such as 5-hydroxy-tryptamine (5-HT), acetylcholine (ACh), and norepinephrine (NEp), inhibited enzyme activity; epinephrine (Ep) stimulated enzyme activity at all ages. Studies on the effects of various concentrations of the transmitters showed that the concentrations of 5-HT, ACh, NEp, and Ep producing significant regulatory effects on the enzyme may be 0.048, 0.18, 0.05, and 0.025 mg/ml, respectively.

scholarly journals Ionic properties of an essential histidine residue in pig heart lactate dehydrogenase

1973 ◽  
Vol 131 (4) ◽  
pp. 729-738 ◽  
Author(s):  
J. John Holbrook ◽  
V. Ann Ingram
Keyword(s):  
Enzyme Activity ◽  
Amino Acid ◽  
Lactate Dehydrogenase ◽  
Side Chains ◽  
Histidine Residue ◽  
Acylating Agent ◽  
Diethyl Pyrocarbonate ◽  
Substrate Analogues ◽  
Amino Acid Side Chains

1. Pig heart lactate dehydrogenase is inhibited by addition of one equivalent of diethyl pyrocarbonate. The inhibition is due to the acylation of a unique histidine residue which is 10-fold more reactive than free histidine. No other amino acid side chains are modified. 2. The carbethoxyhistidine residue slowly decomposes and the enzyme activity reappears. 3. The essential histidine residue is only slightly protected by the presence of NADH but is completely protected when substrate and substrate analogues bind to the enzyme–NADH complex. The protection is interpreted in terms of a model in which substrates can only bind to the enzyme in which the histidine residue is protonated and is thus not available for reaction with the acylating agent. 4. The apparent pKa of the histidine residue in the apoenzyme is 6.8±0.2. In the enzyme–NADH complex it is 6.7±0.2. 5. Acylated enzyme binds NADH with unchanged affinity. The enzyme is inhibited because substrates and substrate analogues cannot bind at the acylated histidine residue in the enzyme–NADH complex.

Molecular characterization of an endo-type chitosanase from the fish pathogenRenibacteriumsp. QD1

2014 ◽  
Vol 94 (4) ◽  
pp. 681-686 ◽  
Author(s):  
Peichuan Xing ◽  
Dan Liu ◽  
Wen-Gong Yu ◽  
Xinzhi Lu
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Specific Activity ◽  
Fermentation Broth ◽  
Maximal Activity ◽  
Optimum Temperature ◽  
Sds Page ◽  
Ph Range ◽  
Tlc Analysis

Renibacteriumsp. QD1, a bacteria strain capable of hydrolysing chitosan, was isolated from the homogenate of small crabs. An extracellular chitosanase, Csn-A, was purified from the QD1 fermentation broth. The enzyme was purified to homogeneity, with a yield of eight-fold, 67% recovery and a specific activity of 1575 U/mg proteins. The molecular weight of Csn-A was estimated to be 26.1 kDa by SDS-PAGE. Unlike other chitosanases, the purified Csn-A displayed maximal activity at a pH range of 5.3–6.5, and it was stable in a broad pH range of 5.0–10.0. The optimum temperature for chitosanlytic activity was 55°C. The enzyme activity was strongly stimulated by Mn2+but inhibited by Fe3+, Cu2+, Al3+, Zn2+and SDS. TLC analysis demonstrated that Csn-A hydrolysed N-deacetylated polymeric glucosamines into chito-biose and -triose in an endo-type manner. The amino acid seuquence of Csn-A showed close identity with an uncharacterized chitosanase of strain ATCC33209.

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