scholarly journals The β-glucosidase from Botryodiplodia theobromae. Mechanism of enzyme-catalysed reactions

1979 ◽  
Vol 179 (3) ◽  
pp. 503-507 ◽  
Author(s):  
G M Umezurike
Keyword(s):  
Maximum Velocity ◽  
Enzymic Activity ◽  
Enzyme Mechanism ◽  
Botryodiplodia Theobromae ◽  
Imidazole Group ◽  
Group 4 ◽  
Effects Of Ph ◽  
Group 3 ◽  
High Concentrations ◽  
Beta Glucosidase

The effects of pH and temperature on Michaelis constant (Km) and maximum velocity (Vmax.) and of NaCl on the activity of the high-molecular-weight beta-glucosidase (beta-D-glucoside glucohydrolase EC 3.2.1.21) from cultures of Botryodiplodia theobromae Pat. have been studied. 2. Donor binding and inhibition of activity by glucose were dependent on the ionization of a group (pK 6.0) that appeared to be an imidazole group. 3. Catalytic activity and the stimulation of activity by glycerol were dependent on the ionization of two groups, which appeared to be a carboxy group and an imidazole group. 4. The Arrhenius activation energy (Ea) calculated from results obtained at pH 4.0 and 5.0 was about 45–46kJ.mol-1. 5. The enthalpies (delta H0) calculated from results obtained at pH 4.0 and 5.0 were similar (about -4kJ.mol-1), whereas at pH 6.5 the value was about -33kJ.mol-1. 6. The entropies (delta S0) calculated from these results at 37 degrees C were -21, -22 and -118J.K-1.mol-1 at pH 4.0, 5.0 and 6.5 respectively. A low concentration of NaCl (16.6 mM) stimulated enzymic activity and decreased the Km for the donor, whereas high concentrations (up to 500 mM) inhibited enzymic activity, increased the Km and had no effect on Vmax. 8. Plots of initial velocity data obtained in the presence of dioxan as 1/v against the ratio of the molar concentration of dioxan to that of water were linear. 9. The results are discussed in terms of the enzyme mechanism.

scholarly journals The active site of β-glucosidase from Botryodiplodia theobromae. Effects of pH and dioxan on enzyme-catalysed reactions

1977 ◽  
Vol 167 (3) ◽  
pp. 831-833 ◽  
Author(s):  
G M Umezurike
Keyword(s):  
Molecular Weight ◽  
Active Site ◽  
Maximum Velocity ◽  
Carboxyl Group ◽  
Michaelis Constant ◽  
Botryodiplodia Theobromae ◽  
Effects Of Ph ◽  
Group 2 ◽  
Beta Glucosidase ◽  
Hydrolysis Of

1. The hydrolysis of o-nitrophenyl beta-D-glucopyranoside by the high-molecular-weight beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) of Botryodiplodia theobromae Pat in the absence or presence of added dioxan was found to be dependent on the ionization of two groups, which appeared to be a carboxyl group and an imidazole group. 2. Dioxan increased the Michaelis constant, Km, but decreased the maximum velocity, V.

scholarly journals Effects of a probiotic in combination with prebiotics on intestinal lactobacilli and coliforms and activities of bacterial enzymes in 1,2-dimethylhydrazine exposed rats

2011 ◽  
Vol 56 (No. 3) ◽  
pp. 99-106 ◽  
Author(s):  
L. Strojný ◽  
A. Bo ◽  
E. Hijová ◽  
A. Chmelárová ◽  
G. Mojžišová ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Control Group ◽  
Group 4 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Beta Glucosidase ◽  
Alpha Glucosidase ◽  
Beta Galactosidase ◽  
Group 1

Effects of the probiotic (PRO) Lactobacillus plantarum and of the combination of PRO and the prebiotic (PRE) inulin enriched with oligofructose (2%), and PRO with Lini oleum virginale (O) on counts of lactobacilli and coliforms and enzymatic activities in faeces of rats were studied. The rats (n = 60) were divided into 5 groups of 12 subjects. The animals were fed on a high fat diet (10%) for 8 weeks of experiment. Colon cancer was induced by the application of 1,2-dimethylhydrazine (DMH) twice a week in a dose of 20 mg/kg s.c. in groups G2-G5. The rats in group 1 (control 1) received a diet without any supplements. The rats in group 2 (control 2) received 1,2 DMH without any supplements. The rats in group 3 received PRO, group 4 PRO and PRE, and group 5 received PRO and O. A significant decrease (P < 0.05) of coliforms was found out after the application of PRO, PRO-O, and PRO-PRE in comparison with control group G2. Significantly higher (P < 0.05) counts of lactobacilli were determined after the application of PRO-O and PRO-PRE. Significantly lower (P < 0.001) activities of β-galactosidase, β-glucuronidase and α-glucosidase were observed in PRO, PRO-PRE and PRO-O, while in the case of the enzyme β-glucosidase the activity was lower only after the addition of PRO-O. The protective effect of lactobacilli was observed in the order PRO-O, PRO-PRE, and PRO. It was shown that combinations of PRO-O and PRO-PRE had a synergistic effect which was higher than the effect of administering only PRO.

scholarly journals The mechanism of action of β-glucosidase from Botryodiplodia theobromae Pat

1987 ◽  
Vol 241 (2) ◽  
pp. 455-462 ◽  
Author(s):  
G M Umezurike
Keyword(s):  
Mechanism Of Action ◽  
Rate Equation ◽  
Enzymic Activity ◽  
Botryodiplodia Theobromae ◽  
Acidic Group ◽  
Linear Decrease ◽  
Low Concentrations ◽  
Acetic Acid Buffer ◽  
Beta Glucosidase ◽  
Enzyme Intermediate

The activity of the high-molecular-weight beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) obtained from culture filtrates of Botryodiplodia theobromae Pat. was affected by added NaCl in such a way that an initial phase of stimulation was followed by a phase of rapid non-linear decrease in velocity and finally by a phase of slow linear decrease in velocity as the concentration of NaCl was increased. In the presence of 0.014 M-sodium acetate/acetic acid buffer (pH 5.0) there was a slight increase in enzymic activity in the presence of low concentrations of dioxan (up to about 10% dioxan) and a rapid decrease in enzymic activity at higher dioxan concentrations, but both effects were mitigated in the presence of 0.1 M buffer. The order of efficiency of added glucosyl acceptors in beta-glucosidase-catalysed reactions was found to be fructose greater than sucrose greater than glycerol greater than methanol. The enzyme was inactivated by the active-site-directed compound conduritol-B-epoxide; but this inactivation was concentration-dependent, was prevented by 10 mM-glucose, and involved an acidic group with pKa 4.3. A rate equation has been derived on the assumption of a mechanism of action involving a solvent-separated and an intimate glucosyl cation-carboxylate ion-pair intermediate and an alpha-glucosyl enzyme intermediate [Umezurike, G. M. (1981) Biochem. J. 199, 203-209]. Calculations based on the application of the derived rate equation and the calculated kinetic parameters show that the rate equation explains the peculiar properties of beta-glucosidase in the presence of added glucosyl acceptors or of NaCl.

scholarly journals The β-glucosidase from Botryodiplodia theobromae. Mechanism of enzyme action

1981 ◽  
Vol 199 (1) ◽  
pp. 203-209 ◽  
Author(s):  
G M Umezurike
Keyword(s):  
Isotope Effect ◽  
Maximum Velocity ◽  
Competitive Inhibitor ◽  
Ion Pair ◽  
High Concentration ◽  
Botryodiplodia Theobromae ◽  
Solvent Isotope Effect ◽  
Kinetic Isotope ◽  
Beta Glucosidase ◽  
Solvent Isotope

1. In the presence of a high concentration of p-nitrophenyl beta-D-glucopyranoside (donor) the rates of production of p-nitrophenol and a transglucosylation product (1-glyceryl beta-D-glucopyranoside) increased, whereas the rate of production of glucose decreased with increasing concentration of glycerol in reactions catalysed by the high-molecular-weight beta-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) obtained from culture filtrates of Botryodiplodia theobromae Pat. 2. When [donor] greater than Km the rate of production of p-nitrophenol was higher in the presence of glycerol than in its absence, whereas when [donor] less than Km the rate of production of p-nitrophenol was lower in the presence of glycerol than in its absence. 3. Glycerol increased both the Michaelis constant (Km) and maximum velocity (Vmax.), whereas dioxan increased Km but decreased Vmax. 4. Up to 1 mM-AgNO3 had no effect on enzyme activity. 5. A 2H-solvent-isotope-effect [Vmax. (H2O)/V max. (2H2O)] value of 1.40 +/- 0.05 was found at pH (or p2H) 5.8 6. alpha-2H-kinetic isotope-effect (kappa H/kappa 2H) values of 1.03 +/- 0.01 and 1.05 +/- 0.01 were found in the absence and presence of glycerol respectively. 7. Although maltose was a non-competitive inhibitor of beta-glucosidase activity, the ratio of velocity in the presence of glycerol to that in its absence increased, after an initial decline, with increasing concentration of maltose. 8. These results are discussed in terms of a mechanism involving a solvent-separated glucosyl cation-carboxylate ion-pair, which has greater affinity for alcoholic glucosyl acceptors, and an intimate ion-pair, which has greater affinity for water as a glucosyl acceptor and which could collapse reversibly and rapidly into a preponderance of an unreactive covalent glucosyl-enzyme.

Morphological Changes in the Rat Granulosa Cell Surface During Differentiation Induced by Estradiol and Gonadotropins

1977 ◽  
Vol 35 ◽  
pp. 484-485
Author(s):  
P. Bagavandoss ◽  
JoAnne S. Richards ◽  
A. Rees Midgley
Keyword(s):  
Cell Surface ◽  
Granulosa Cell ◽  
Morphological Changes ◽  
Follicular Development ◽  
Female Rats ◽  
Functional Changes ◽  
Group 4 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2

During follicular development in the mammalian ovary, several functional changes occur in the granulosa cells in response to steroid hormones and gonadotropins (1,2). In particular, marked changes in the content of membrane-associated receptors for the gonadotropins have been observed (1).We report here scanning electron microscope observations of morphological changes that occur on the granulosa cell surface in response to the administration of estradiol, human follicle stimulating hormone (hFSH), and human chorionic gonadotropin (hCG).Immature female rats that were hypophysectcmized on day 24 of age were treated in the following manner. Group 1: control groups were injected once a day with 0.1 ml phosphate buffered saline (PBS) for 3 days; group 2: estradiol (1.5 mg/0.2 ml propylene glycol) once a day for 3 days; group 3: estradiol for 3 days followed by 2 days of hFSH (1 μg/0.1 ml) twice daily, group 4: same as in group 3; group 5: same as in group 3 with a final injection of hCG (5 IU/0.1 ml) on the fifth day.

Correlation of γ-radioactivity and Scanning Electron Microscopy in measurement of retention of 111Indium-labeled canine endothelial cells on synthetic vascular grafts

1989 ◽  
Vol 47 ◽  
pp. 886-887
Author(s):  
E.J. Prendiville ◽  
S. Laliberté Verdon ◽  
K. E. Gould ◽  
K. Ramberg ◽  
R. J. Connolly ◽  
...  
Keyword(s):  
Blood Flow ◽  
Ex Vivo ◽  
Vascular Grafts ◽  
Retention Data ◽  
Vascular Prostheses ◽  
Group 4 ◽  
Human Fibronectin ◽  
Insufficient Time ◽  
Group 3 ◽  
Group 2

Endothelial cell (EC) seeding is postulated as a mechanism of improving patency in small caliber vascular grafts. However the majority of seeded EC are lost within 24 hours of restoration of blood flow in previous canine studies . We postulate that the cells have insufficient time to fully develop their attachment to the graft surface prior to exposure to hemodynamic stress. We allowed EC to incubate on fibronectin-coated ePTFE grafts for four different time periods after seeding and measured EC retention after perfusion in a canine ex vivo shunt circuit.Autologous canine EC, were enzymatically harvested, grown to confluence, and labeled with 30 μCi 111 Indium-oxine/80 cm 2 flask. Four groups of 5 cm x 4 mm ID ePTFE vascular prostheses were coated with 1.5 μg/cm.2 human fibronectin, and seeded with 1.5 x 105 EC/ cm.2. After seeding grafts in Group 1 were incubated in complete growth medium for 90 minutes, Group 2 were incubated for 24 hours, Group 3 for 72 hours and Group 4 for 6 days. Grafts were then placed in the canine ex vivo circuit, constructed between femoral artery and vein, and subjected to blood flow of 75 ml per minute for 6 hours. Continuous counting of γ-activity was made possible by placing the seeded graft inside the γ-counter detection crystal for the duration of perfusion. EC retention data after 30 minutes, 2 hours and 6 hours of flow are shown in the table.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin
Keyword(s):  
Vascular Graft ◽  
Graft Infection ◽  
Vascular Graft Infection ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Prosthetic Vascular Graft Infection ◽  
Group 1

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

Defensive activity of Hesperidin against Ciprofloxacin induced hepatic injury in rabbits.

2019 ◽  
Vol 10 (03) ◽  
Author(s):  
Hawraa M. Murad ◽  
Tamadhur Hani Hussein ◽  
Audai Sulaiman Khudhair ◽  
Manal Muhi Murad ◽  
Jawad Kadhim Faris
Keyword(s):  
Body Weight ◽  
Bacterial Infections ◽  
Hepatoprotective Activity ◽  
The Body ◽  
Local Breed ◽  
Group 4 ◽  
Group 3 ◽  
Group 2 ◽  
Defensive Activity ◽  
Antioxidant Effects

This study was conducted to find out hepatoprotective activity of hesperidin (HES) 100mg/kg body weight (b.w.) against ciprofloxacin (CPX) 100 mg/kg induced hepatotoxicity in local breed rabbits .CPX is a broad spectrum antibiotic used for treatment of many bacterial infections. Twenty four male rabbits were divided into four groups ,group1: control, (1 ml/kg Saline orally) group 2: CPX (100 mg/kg orally) for (14) consecutive days , group 3: HES (100 mg//kg) orally for (14) consecutive days group 4: CPX (100 mg/kg orally) plus HES (100 mg//kg orally ) for (14) consecutive days. All the rabbits were killed on the (15) day of the experiment, and then the blood, and livers samples were taken. CPX induced hepatotoxicity was proved by a significant (p less than 0.01) reduction in the body weight ,and a significant (p less than 0.01) increased serum aspartate transaminase (AST), alanine transaminase (ALT) , Malonaldehyde enzyme (MAD) and histopathological changes. Protective hepatic toxicity effect and oxidative damage caused by CPX significantly (p less than 0.01) increasing in body weight and significantly (p less than 0.01) decreasing AST , ALT, MAD and improving tissue morphology in HES (100 mg//kg) . These results assure that HES (100 mg//kg) antioxidant effects can protect CPX-induced hepatotoxicity in rabbits.

Does Perioperative Hemoglobin A1c Level Affect the Incidence, Pattern and Mortality of Lower Extremity Amputation?

2019 ◽  
Vol 17 (4) ◽  
pp. 354-364
Author(s):  
Hassan Al-Thani ◽  
Moamena El-Matbouly ◽  
Maryam Al-Sulaiti ◽  
Noora Al-Thani ◽  
Mohammad Asim ◽  
...  
Keyword(s):  
Glycemic Control ◽  
Lower Extremity ◽  
Hazard Ratio ◽  
Lower Extremity Amputation ◽  
Group 4 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Extremity Amputation ◽  
Group 1

Background: We hypothesized that perioperative HbA1c influenced the pattern and outcomes of Lower Extremity Amputation (LEA). Methods: A retrospective analysis was conducted for all patients who underwent LEA between 2000 and 2013. Patients were categorized into 5 groups according to their perioperative HbA1c values [Group 1 (<6.5%), Group 2 (6.5-7.4%), Group 3 (7.5-8.4%), Group 4 (8.5-9.4%) and Group 5 (≥9.5%)]. We identified 848 patients with LEA; perioperative HbA1c levels were available in 547 cases (Group 1: 18.8%, Group 2: 17.7%, Group 3: 15.0%, Group 4: 13.5% and Group 5: 34.9%). Major amputation was performed in 35%, 32%, 22%, 10.8% and 13.6%, respectively. Results: The overall mortality was 36.5%; of that one quarter occurred during the index hospitalization. Mortality was higher in Group 1 (57.4%) compared with Groups 2-5 (46.9%, 38.3%, 36.1% and 31.2%, respectively, p=0.001). Cox regression analysis showed that poor glycemic control (Group 4 and 5) had lower risk of mortality post-LEA [hazard ratio 0.57 (95% CI 0.35-0.93) and hazard ratio 0.46 (95% CI 0.31-0.69)]; this mortality risk persisted even after adjustment for age and sex but was statistically insignificant. The rate of LEA was greater among poor glycemic control patients; however, the mortality was higher among patients with tight control. Conclusion: The effects of HbA1c on the immediate and long-term LEA outcomes and its therapeutic implications need further investigation.

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