Mechanism of the feedback-inhibition resistance in aspartate kinase of Corynebacterium pekinense: from experiment to MD simulations

RSC Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 30-38
Author(s):  
Xiaoting Liu ◽  
Caijing Han ◽  
Li Fang ◽  
Zhanqing Fan ◽  
Yanan Wang ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Feedback Inhibition ◽  
Md Simulations ◽  
Aspartate Kinase ◽  
High Enzyme ◽  
High Enzyme Activity

Corynebacterium pekinense AK was successfully modified and two mutants A380C and T379N/A380C with high enzyme activity were constructed. The mechanism of their feedback-inhibition resistance was thoroughly studied from experiment to MD simulations.

Su1843 High Enzyme Activity UGT1A1 or Low Activity Ugt1a8 and Ugt2b4 Genotypes Increase Esophageal Cancer Risk

2012 ◽  
Vol 142 (5) ◽  
pp. S-517
Author(s):  
Polat Dura ◽  
Jody Salomon ◽  
Rene te Morsche ◽  
Hennie Roelofs ◽  
Jon Kristinsson ◽  
...  
Keyword(s):  
Esophageal Cancer ◽  
Enzyme Activity ◽  
Cancer Risk ◽  
High Enzyme ◽  
Low Activity ◽  
High Enzyme Activity

Internodal invertases and stalk maturity in sugarcane

1991 ◽  
Vol 116 (2) ◽  
pp. 239-243 ◽  
Author(s):  
H. L. Sehtiya ◽  
J. P. S. Dendsay ◽  
A. K. Dhawan
Keyword(s):  
Enzyme Activity ◽  
Cell Expansion ◽  
Reducing Sugars ◽  
Sucrose Solution ◽  
Invertase Activity ◽  
Neutral Invertase ◽  
High Enzyme ◽  
Stem Slices ◽  
High Enzyme Activity

SUMMARYAcid and neutral invertase activities in the stem of an early (CoJ 64) and a late cultivar (Col 148) of sugarcane were estimated by incubating stem slices in buffered sucrose solution and measuring the production of reducing sugars. High enzyme activity occurred in young tissue but the activity of both enzymes was considerably lower in the mature internodes. Acid and neutral invertase activity was highest in the midinternode position, corresponding to the region of cell expansion.

Preparation of enzymatically highly active pegylated-D-amino acid oxidase and its application to antitumor therapy

2021 ◽  
Vol 18 ◽  
Author(s):  
Hideaki Nakamura ◽  
Appiah Enoch ◽  
Shotaro Iwaya ◽  
Sakura Furusho ◽  
Shoko Tsunoda ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Antitumor Effect ◽  
Tumor Tissue ◽  
Acid Oxidase ◽  
Antitumor Therapy ◽  
Amino Acid Oxidase ◽  
Tumor Bearing ◽  
Highly Active ◽  
High Enzyme ◽  
High Enzyme Activity

Background: D-amino acid oxidase (DAO) is an H2O2-generating enzyme, and tumor growth suppression by selective delivery of porcine DAO in tumors via the cytotoxic action of H2O2 has been reported. DAO isolated from Fusarium spp. (fDAO) shows much higher enzyme activity than porcine DAO, although the application of fDAO for antitumor treatment has not yet been determined. Objective: The purpose of this study was to prepare enzymatically highly active pegylated-fDAO, and to determine whether it accumulates in tumors and exerts a potent antitumor effect in tumor-bearing mice. Methods: Polyethylene glycol (PEG; Mw. 2000) was conjugated to fDAO to form PEGylated fDAO (PEG-fDAO). PEGfDAO was intravenously administered into S180 tumor-bearing mice, and the body distribution and antitumor activity of PEG-fDAO was determined. Results: The enzyme activity of PEG-fDAO was 26.1 U/mg, which was comparable to that of fDAO. Intravenously administered PEG-fDAO accumulated in tumors with less distribution in normal tissue except in the plasma. Enzyme activity in the tumor was 60–120 mU/g-tissue over 7–20 h after i.v. injection of 0.1 mg of PEG-fDAO. To generate the H2O2 in the tumor tissue, PEG-fDAO was intravenously administered, and then, D-phenylalanine was intraperitoneally administered after a lag time. No remarkable tumor suppression effect was observed under conditions used in this study, compared to the non-treated group. Conclusion: The results suggest that PEG-fDAO maintained high enzymatic activity after pegylation. Treatment with PEGfDAO conferred high enzyme activity on tumor tissue; 3–6 fold higher than that of previously reported pDAO; however, high enzyme activity in the plasma limited repeated treatment owing to lethal toxicity, which seemingly led to poor therapeutic outcome. Overall, the use of PEG-fDAO is promising for antitumor therapy, although the suppression of DAO activity in the plasma would also be required rather than only the increase in DAO activity in the tumor for an antitumor effect.

A Study of the Colorimetric Dinitrophenylhydrazine Method for the Determination of Serum Glutamic Oxalacetic Transaminase Activity

1966 ◽  
Vol 12 (4) ◽  
pp. 217-225 ◽  
Author(s):  
J S Annino
Keyword(s):  
Enzyme Activity ◽  
Transaminase Activity ◽  
Reagent Blank ◽  
Glutamic Oxalacetic Transaminase ◽  
Color Development ◽  
High Enzyme ◽  
Serum Glutamic Oxalacetic Transaminase ◽  
The Relationship ◽  
High Enzyme Activity

Abstract Study of the colorimetric transaminase method of Reitman and Frankel for the determination of serum glutamic oxalacetic transaminase activity revealed the following: (1) although maximum absorption occurs at 444 mµ, absorbance readings at 505 mµ gave satisfactory results; (2) color development is immediate and the color is stable for at least 1 hr.; (3) a pyruvate calibration standard may be used; (4) sample blanks are not usually necessary; (5) a reagent blank should accompany each group of analyses and should be used as a photometric reference; (6) the relationship between dilution and enzyme activity is linear; and (7) although the relationship between incubation time and activity is not exactly linear, a factor has been determined to permit the use of a 12-min. incubation period with samples showing high enzyme activity.

EFFECT OF THE THYROID GLAND ON PSEUDOCHOLINESTERASE ACTIVITY IN THE LIVER AND SERUM OF THE RAT

1966 ◽  
Vol 52 (3) ◽  
pp. 368-374 ◽  
Author(s):  
R. S. Leeuwin
Keyword(s):  
Enzyme Activity ◽  
Thyroid Gland ◽  
Female Rats ◽  
Male Rats ◽  
High Enzyme ◽  
Combined Actions ◽  
High Enzyme Activity

ABSTRACT The effect of the thyroid gland on the pseudocholinesterase activity has been investigated. Whereas in female rats the pseudocholinesterase activity is not affected by thyroidectomy, the activity in the liver and serum of male rats is significantly increased after thyroidectomy. In castrated and thyroidectomized male rats, the pseudocholinesterase activity markedly exceeds that of either the castration or the thyroidectomy level; the effects are additive and independent In female rats, thyroidectomy causes an increase of pseudocholinesterase activity in spayed animals. Administration of thyroxine is followed by a decrease in the pseudocholinesterase activity of castrated-thyroidectomized males. It is concluded that the thyroid gland as well as the gonads control the pseudocholinesterase activity: in male rats the relatively low pseudocholinesterase activity is maintained by the combined actions of the gonads and the thyroid gland, whereas in female rats, the thyroid gland does not affect the relatively high enzyme activity induced by the ovarian oestrogens.

Genetic and Biochemical Studies on the Conversion of Dihydroflavonols to Flavonols in Flowers of Petunia hybrida

1986 ◽  
Vol 41 (1-2) ◽  
pp. 179-186 ◽  
Author(s):  
G. Forkmann ◽  
P. de Vlaming ◽  
R. Spribille ◽  
H. Wiering ◽  
A. W. Schram
Keyword(s):  
Enzyme Activity ◽  
Petunia Hybrida ◽  
Soluble Enzyme ◽  
Flower Buds ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
Biochemical Studies ◽  
High Enzyme ◽  
Substantial Correlation ◽  
High Enzyme Activity

Abstract Soluble enzyme preparations from flower buds of Petunia hybrida catalyzed the conversion of dihydroflavonols to flavonols. Dihydrokaempferol and dihydroquercetin were readily converted to the respective flavonols, whereas dihydromyricetin was a poor substrate. The reaction required 2-oxoglutarate, ascorbate and Fe2+ as cofactors and had a pH optimum at about 6.5. In the presence of the dominant allele Fl, high enzyme activity for flavonol formation was found, whereas in enzyme preparations from flower buds of recessive genotypes (fl/fl) only low enzyme activity could be observed. A substantial correlation was found between enzyme activity for flavonol formation and the flavonol content of buds and flowers during development.

scholarly journals Pre-apoptotic Alterations in Hepatocytes of TNF α-treated Galactosamine-sensitized Mice

1998 ◽  
Vol 46 (10) ◽  
pp. 1175-1183 ◽  
Author(s):  
Sabine Angermüller ◽  
Gerald Künstle ◽  
Gisa Tiegs
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Chromatin Condensation ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
High Enzyme ◽  
Dna Strand ◽  
High Enzyme Activity

Tumor necrosis factor (TNF) induces apoptotic death of hepatocytes in the galactosamine (GalN)-sensitized mouse liver after 5 hr. In our study, the most remarkable sign of the early stage of apoptosis was the focal rupture of the outer mitochondrial membrane. Parts of the inner membrane extended through the gap of the outer membrane, whereas the rest of the inner membrane still formed the cristae. This feature appeared in hepatocytes before chromatin condensation. With the diaminobenzidine technique for localization of cytochrome oxidase activity, the reaction product was detectable by light and electron microscopy. Ten percent of the hepatocytes were apoptotic, with condensed chromatin and high enzyme activity, 37% were pre-apoptotic, without chromatin condensation but high enzyme activity, and 53% had neither condensed chromatin nor a remarkable reaction product of cytochrome oxidase activity. Fas (APO-1, CD95) molecules on the plasma membrane of hepatocytes increased and were represented immunohistochemically in cells without chromatin condensation. DNA strand breaks were also detectable before chromatin aggregation. The results of this study indicate that mitochondria play a pivotal role in pre-apoptotic hepatocytes, together with an increase of the Fas molecule on the plasma membrane and with the occurrence of DNA strand breaks in the nucleus.

Coupling high enzyme activity and stability: a challenging target

2000 ◽  
Vol 18 (10) ◽  
pp. 401-402 ◽  
Author(s):  
Giacomo Carrea ◽  
Giorgio Colombo
Keyword(s):  
Enzyme Activity ◽  
High Enzyme ◽  
High Enzyme Activity
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