THE INTERCONVERSION OF GLYCINE AND SERINE IN ZEA MAYS

1959 ◽  
Vol 37 (1) ◽  
pp. 887-894 ◽  
Author(s):  
A. H. W. Hauschild
Keyword(s):  
Zea Mays ◽  
Equilibrium Constant ◽  
Enzyme Preparation ◽  
Pyridoxal Phosphate ◽  
Soluble Fraction ◽  
Activity Curve

Glycine and formaldehyde are converted into serine in the presence of a dialyzed, lyophilized enzyme preparation from corn seedlings, with tetrahydropteroylglutamic acid and pyridoxal phosphate as coenzymes. The equilibrium constant of the reaction was calculated for the system at 37.5 °C as K = 3.1 × 103. The pH activity curve showed a maximum between 6.6 and 7.0. The effects of the concentrations of the coenzymes were studied. The glycine–serine interconverting enzyme is present throughout the seedling and occurs exclusively in the soluble fraction of the cells.

THE INTERCONVERSION OF GLYCINE AND SERINE IN ZEA MAYS

1959 ◽  
Vol 37 (7) ◽  
pp. 887-894 ◽  
Author(s):  
A. H. W. Hauschild
Keyword(s):  
Zea Mays ◽  
Equilibrium Constant ◽  
Enzyme Preparation ◽  
Pyridoxal Phosphate ◽  
Soluble Fraction ◽  
Activity Curve

Glycine and formaldehyde are converted into serine in the presence of a dialyzed, lyophilized enzyme preparation from corn seedlings, with tetrahydropteroylglutamic acid and pyridoxal phosphate as coenzymes. The equilibrium constant of the reaction was calculated for the system at 37.5 °C as K = 3.1 × 103. The pH activity curve showed a maximum between 6.6 and 7.0. The effects of the concentrations of the coenzymes were studied. The glycine–serine interconverting enzyme is present throughout the seedling and occurs exclusively in the soluble fraction of the cells.

STUDIES ON CORTICOSTERONE C-20 REDUCTION IN THE MOUSE

1962 ◽  
Vol 40 (1) ◽  
pp. 1797-1810 ◽  
Author(s):  
R. E. Krehbiel ◽  
A. F. Burton ◽  
Marvin Darrach
Keyword(s):  
Intravenous Injection ◽  
Mouse Liver ◽  
Enzyme Preparation ◽  
Soluble Fraction ◽  
Reductase Activity ◽  
Kinetics Of

The intravenous injection of corticosterone in the mouse was followed by liver assays for corticosterone and 20α- and 20β-dihydrocorticosterone. The 20α-epimer proved to be the more abundant product. Corticosterone 20α-reductase activity of mouse liver was shown to be associated with the dialyzed soluble fraction of the cell which served as an enzyme preparation for a study of certain properties of corticosterone 20α-reductase and the kinetics of the forward and reverse reactions.

scholarly journals The mechanism of action of serine transhydroxymethylase

1970 ◽  
Vol 116 (2) ◽  
pp. 277-286 ◽  
Author(s):  
P. M. Jordan ◽  
M. Akhtar
Keyword(s):  
Schiff Base ◽  
Amino Acid ◽  
Hydrogen Atom ◽  
Mechanism Of Action ◽  
Active Site ◽  
Enzyme Preparation ◽  
Pyridoxal Phosphate ◽  
Acid Oxidase ◽  
Amino Acid Oxidase

1. The preparation of stereospecifically tritiated glycines and the determination of their absolute configurations by the use of d-amino acid oxidase are described. 2. The reaction catalysed by serine transhydroxymethylase, which results in the conversion of glycine into serine, has been separated into at least four partial reactions. It is suggested that the first event in this conversion is the formation of a Schiff base intermediate of glycine and pyridoxal phosphate. The next important step involves the removal of the 2S-hydrogen atom of glycine to give a carbanion intermediate. Experiments pertinent to the mechanism of conversion of this carbanion intermediate into serine are described. 3. The enzyme preparation catalysing the conversion of glycine into serine also participates in the conversion of glycine into threonine and allothreonine. In both these conversions, glycine → serine and glycine → threonine, the 2S-hydrogen atom of glycine is eliminated and the 2R-hydrogen atom of glycine is retained. 4. In the light of these experiments the mechanism of action of serine transhydroxymethylase is discussed. It is suggested that methylenetetrahydrofolate is the carrier of formaldehyde, from which formaldehyde may be liberated at the active site of the enzyme, thus allowing the overall reaction to take place.

Isolation and Properties of Functional Mesophyll Protoplasts and Chloroplasts From Zea mays

1981 ◽  
Vol 8 (1) ◽  
pp. 21 ◽  
Author(s):  
DA Day ◽  
CLD Jenkins ◽  
MD Hatch
Keyword(s):  
Zea Mays ◽  
Oxygen Evolution ◽  
Pyridoxal Phosphate ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
The Other ◽  
Mesophyll Protoplasts ◽  
Intact Chloroplasts ◽  
Common Carrier ◽  
High Concentrations

A procedure is described for the preparation of metabolically active mesophyll protoplasts from maize, and of functional, intact chloroplasts from these protoplasts. Intact protoplasts show no oxygen evolution with 3-phosphoglycerate or with oxalacetate plus pyruvate as substrates, even when these substances are provided at high concentrations. On the other hand, protoplast extracts and chloroplasts display rates of oxygen evolution of 2-3 �mol min-1 (mg Chl)-1 with the same substances. Pyruvate stimulates oxalacetate-dependent oxygen evolution substantially, indicating good coupling between non-cyclic electron flow and phosphorylation. Low PI concentrations stimulate 3-phosphoglycerate-dependent oxygen evolution; high PI concentrations, and pyridoxal phosphate, inhibit this activity, suggesting a common carrier for 3-phosphoglycerate and PI.

5′-Nucleotidase of Testes of Immature Sockeye Salmon (Oncorhynchus nerka)

1970 ◽  
Vol 27 (11) ◽  
pp. 2003-2007
Author(s):  
Linda J. Gardner
Keyword(s):  
High Speed ◽  
Sockeye Salmon ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Oncorhynchus Nerka ◽  
Single Peak ◽  
Nucleotidase Activity ◽  
Activity Curve

Fifty percent of the salmon 5′-nucleotidase is in the soluble fraction after high-speed centrifugation. A threefold purification on a Sephadex G-200 column gives a specific activity of 0.5 μmoles UMP hydrolyzed per hour per milligram of protein. The pH activity curve gives a single peak with an optimum at pH 9.0 MgCl2, CaCl2, and MnSO4 increase the activity whereas Zn acetate, Ni acetate, and CoSO4 inhibit the enzyme. EDTA, KF 2-mercaptoethanol, and dithiothreitol inhibit the nucleotidase activity. It is stable for up to 1 week at 0 C and up to 2 hr at 35 C, but activity decreases to 50% after 15 min at 50 C and no activity is left after 15 min at 60 C. The nucleotidase shows greatest activity towards 5′-nucleotides; 2′(3′) nucleotides and 5′-deoxynucleotides are hydrolyzed less effectively. Ribose-5-phosphate and p-nitrophenylphosphate are hydrolyzed, but no activity is exhibited against fructose-1-phosphate and α-glycerophosphate.

STUDIES ON CORTICOSTERONE C-20 REDUCTION IN THE MOUSE

1962 ◽  
Vol 40 (12) ◽  
pp. 1797-1810 ◽  
Author(s):  
R. E. Krehbiel ◽  
A. F. Burton ◽  
Marvin Darrach
Keyword(s):  
Intravenous Injection ◽  
Mouse Liver ◽  
Enzyme Preparation ◽  
Soluble Fraction ◽  
Reductase Activity ◽  
Kinetics Of

The intravenous injection of corticosterone in the mouse was followed by liver assays for corticosterone and 20α- and 20β-dihydrocorticosterone. The 20α-epimer proved to be the more abundant product. Corticosterone 20α-reductase activity of mouse liver was shown to be associated with the dialyzed soluble fraction of the cell which served as an enzyme preparation for a study of certain properties of corticosterone 20α-reductase and the kinetics of the forward and reverse reactions.

scholarly journals Enzymic sulphation of p-nitrophenol and steroids by larval gut tissues of the southern armyworm (Prodenia eridania Cramer)

1972 ◽  
Vol 130 (2) ◽  
pp. 487-493 ◽  
Author(s):  
R. S. H. Yang ◽  
C. F. Wilkinson
Keyword(s):  
Enzyme Preparation ◽  
Soluble Fraction ◽  
Enzyme System ◽  
Endocrine Control ◽  
Southern Armyworm ◽  
Inorganic Sulphate

1. An enzyme system that catalyses the sulphation of p-nitrophenol, cholesterol, α-ecdysone, β-sitosterol, dehydroepiandrosterone, oestrone and four other steroids of plant and insect origin was obtained from the soluble fraction of southern-armyworm gut tissues. 2. The enzyme system required ATP and inorganic sulphate, and activity was slightly enhanced in the presence of GSH. 3. The properties of this enzyme system with respect to pH, temperature, substrate and protein concentrations and various cofactors and reagents were studied. At −23°C the enzyme preparation could be stored for 2 weeks without drastic loss of activity. At the end of storage for 1 month the loss of activity was approx. 21%. 4. The possible involvement of this enzyme system in insect endocrine control is discussed.

Metabolism of EPTC in Corn (Zea mays)

Weed Science ◽  
1978 ◽  
Vol 26 (2) ◽  
pp. 157-160 ◽  
Author(s):  
R. D. Carringer ◽  
C. E. Rieck ◽  
L. P. Bush
Keyword(s):  
Zea Mays ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Amino Acid Analysis ◽  
Soluble Fraction ◽  
Degradation Products ◽  
Reduced Glutathione ◽  
Water Soluble ◽  
Glutathione Conjugate ◽  
Water Soluble Fraction

EPTC (S-ethyl dipropylthiocarbamate) metabolism in corn (Zea mays L. ‘inbred B37’) was studied utilizing carbonyl-14C-EPTC and propyl-1-14C-EPTC. Two radioactive compounds were found in the organic-soluble fraction, namely, EPTC and EPTC-sulfoxide. Five metabolites were found in the water-soluble fraction. Amino acid analysis indicated that one water-soluble metabolite was a glutathione conjugate [S-(N,N-dipropylcarbamyl)glutathione] and that three other metabolites were probably degradation products of the glutathione conjugate. It was determined that EPTC-sulfoxide reacts chemically with reduced glutathione, yielding the conjugate. There was no detectable glutathione S-transferase enzyme activity associated with the sulfoxide cleavage.

Cellulases of an alkalophilic Bacillus strain isolated from soil

1984 ◽  
Vol 30 (6) ◽  
pp. 774-779 ◽  
Author(s):  
K. Horikoshi ◽  
M. Nakao ◽  
Y. Kurono ◽  
N. Sashihara
Keyword(s):  
Carboxymethyl Cellulose ◽  
Enzyme Preparation ◽  
Bacillus Sp ◽  
Bacillus Pasteurii ◽  
Crude Enzyme Preparation ◽  
Cmcase Activity ◽  
Multienzyme System ◽  
Activity Curve ◽  
Alkalophilic Bacillus ◽  
Optimal Ph

A cellulolytic alkalophile, Bacillus sp. No. N-4, was isolated from soil and found to be similar to Bacillus pasteurii, except for its ability to grow at high pH. The isolate grew well at a pH ranging from about 8 to 11 and was a good producer of carboxymethyl cellulase (CMCase) activity, which was associated with a multienzyme system. The crude enzyme preparation strongly hydrolyzed carboxymethyl cellulose and had a broad pH activity curve (pH 5–10). Two alkaline CMCases (enzyme E1 and E2) having an optimal pH for enzyme action at pH 10.0 were partially purified. The enzyme E2 was stable up to 80 °C, and E1 up to 60 °C. Both enzymes hydrolyzed cellotetraose and preferentially yielded cellobiose.

Sign in / Sign up

Export Citation Format

Share Document