STUDIES ON A LIPOXIDASE SYSTEM FROM SUNFLOWER SEEDS AND SEEDLINGS

1958 ◽  
Vol 36 (11) ◽  
pp. 1149-1157 ◽  
Author(s):  
Oluf L. Gamborg ◽  
Saul Zalik
Keyword(s):  
Kinetic Studies ◽  
Maximum Activity ◽  
Sunflower Seeds ◽  
Reaction Products ◽  
Total Oxidation ◽  
Ph Optimum ◽  
Potassium Oleate ◽  
Enzyme Preparations ◽  
Cytoplasmic Proteins ◽  
Total Fat

Lipoxidase activity was obtained in enzyme preparations from sunflower seeds and seedlings. A partly purified preparation from seedlings was used for enzyme kinetic studies. The pH optimum was 6.8 and 100% oxygen was required for maximum activity. The Michaelis constant, with potassium linoleate as substrate, was 1.64 × 10−3 M. The reaction products were conjugated dienes. Enzyme activity was not affected by various metal and sulphydryl inhibitors nor by α-tocopherol, but catechol, α-naphthol, ethanol, and potassium oleate were inhibitory. Oil from flax, rape, and sunflower seeds reduced total oxidation of linoleate by the enzyme. Copper sulphate increased the rate and total oxidation of the linoleate–lipoxidase system, but iron, manganese, magnesium, and calcium were without effect. Lipoxidase activity was associated with mitochondrial (15,000 × g), intermediate (25,000 × g), and microsomal (100,000 × g) fractions, as well as with the soluble cytoplasmic proteins. Lipoxidase activity in seedlings increased during initial stages of germination, then decreased. The most rapid depletion of total fat in the seedlings coincided with maximum lipoxidase activity.

STUDIES ON A LIPOXIDASE SYSTEM FROM SUNFLOWER SEEDS AND SEEDLINGS

1958 ◽  
Vol 36 (1) ◽  
pp. 1149-1157 ◽  
Author(s):  
Oluf L. Gamborg ◽  
Saul Zalik
Keyword(s):  
Kinetic Studies ◽  
Maximum Activity ◽  
Sunflower Seeds ◽  
Reaction Products ◽  
Total Oxidation ◽  
Ph Optimum ◽  
Potassium Oleate ◽  
Enzyme Preparations ◽  
Cytoplasmic Proteins ◽  
Total Fat

Lipoxidase activity was obtained in enzyme preparations from sunflower seeds and seedlings. A partly purified preparation from seedlings was used for enzyme kinetic studies. The pH optimum was 6.8 and 100% oxygen was required for maximum activity. The Michaelis constant, with potassium linoleate as substrate, was 1.64 × 10−3 M. The reaction products were conjugated dienes. Enzyme activity was not affected by various metal and sulphydryl inhibitors nor by α-tocopherol, but catechol, α-naphthol, ethanol, and potassium oleate were inhibitory. Oil from flax, rape, and sunflower seeds reduced total oxidation of linoleate by the enzyme. Copper sulphate increased the rate and total oxidation of the linoleate–lipoxidase system, but iron, manganese, magnesium, and calcium were without effect. Lipoxidase activity was associated with mitochondrial (15,000 × g), intermediate (25,000 × g), and microsomal (100,000 × g) fractions, as well as with the soluble cytoplasmic proteins. Lipoxidase activity in seedlings increased during initial stages of germination, then decreased. The most rapid depletion of total fat in the seedlings coincided with maximum lipoxidase activity.

FERMENTATIVE HYDROLYTIC PREPARATION METHODS OF CEREAL WORT FOR ALCOHOL FERMENTATION

1970 ◽  
pp. 52-56
Author(s):  
Е. M. Serba ◽  
М. B. Overchenko ◽  
L. V. Rimareva ◽  
N. I. Ignatova ◽  
А. E. Orekhova ◽  
...  
Keyword(s):  
Alcoholic Fermentation ◽  
Raw Materials ◽  
Alcohol Concentration ◽  
Activity Level ◽  
Optimal Dosage ◽  
Main Role ◽  
Alcohol Fermentation ◽  
Ph Optimum ◽  
Amylolytic Enzyme ◽  
Enzyme Preparations

In the production of alcohol in the preparation of grain raw materials for fermentation, the main role is given to enzyme preparations of amylolytic action, which are key enzymes that catalyze the hydrolysis of starch. Amylolytic enzyme preparations with a different composition of enzymes and their level of activity, a mechanism of biocatalytic effect on starch, and a range of thermal and pH optimum are widely represented on the Russian market. The development of optimal conditions for the preparation of grain wort, the rational selection and dosage of concentrated enzyme preparations, the properties of which correspond to the parameters of the technological process, will ensure the effective preparation of starch for fermentation, and increase the profitability of alcohol production. The aim of this work was to study the influence of enzyme preparations of amylolytic action and the conditions of their use on the efficiency of the process of alcoholic fermentation and the yield of the final product, ethanol. The effect of various dosages of enzyme preparations of glucoamylase action, with a different ratio of the main enzyme glucoamylase and minor enzyme α-amylase, as well as methods for preparing wheat wort on the process of alcoholic fermentation, was studied. It was found that the enzyme preparation, the source of glucoamylase, in which α-amylase was present in a ratio of 15: 1 (in terms of activity level), turned out to be more effective in fermenting prepared wheat wort: its optimal dosage was 8 units. GLS / g starch. The presence of a sufficient amount of α-amylase in this preparation compensated for the dosage of thermostable α-amylase. The alcohol concentration in the mash was 10.2% vol., The alcohol yield was 67.9 cm3 / 100 g of starch. When glucoamylase with a lower ratio of the main and minor enzyme (75: 1) was used at the saccharification stage, an increase in the wort fermentation depth was observed with an increase in the concentration of glucoamylase to 9-10 units of GLS / g and α-amylase to 0.5 units. AC / g. It was also found that an increase in the duration of enzymatic-hydrolytic preparation of the wort had a positive effect on the fermentation process, the alcohol concentration in the mash increased to 10.2 vol.%. It was shown that the introduction of proteases into the wort helps to reduce the viscosity of grain wort, enriching it with assimilable yeast amino acids, which leads to an increase in the yield of alcohol. It has been confirmed that the synergy of the action of enzymes of amylolytic and proteolytic effects on polymers of grain raw materials allows to increase the efficiency of their conversion to ethanol. The conditions of enzymatic-hydrolytic processing of grain raw materials for fermentation are developed. The use of the digestion stage did not significantly affect the fermentation results of wheat wort.

Pyridine–Adenine Dinucleotide Transhydrogenase Activity in Cells Cultured from Rat Hepatoma

1972 ◽  
Vol 50 (5) ◽  
pp. 447-456 ◽  
Author(s):  
C. De Luca ◽  
R. P. Gioeli
Keyword(s):  
Phosphate Buffer ◽  
Pyridine Nucleotide ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Apparent Lack ◽  
Minimal Deviation ◽  
Ph Range ◽  
Pyridine Nucleotide Transhydrogenase ◽  
Rat Hepatoma ◽  
Cells Cultured

Preparations from cells cultured from a minimal-deviation hepatoma in the rat exhibit pyridine nucleotide transhydrogenase (NAD(P)H: NAD(P) oxidoreductase, EC 1.6.1.1) activity. The pH optimum, its release by digitonin, and its apparent lack of dependence on steroids for activity tentatively classify it as a transhydrogenase of the type first described for animal tissue.Enzyme preparations from digitonin-treated homogenates were very unstable. The time necessary for the loss of one-half the activity was 16–18 h when the enzyme was stored at 5 °C; this was reduced to 4 h when storage was in polycarbonate tubes.The enzyme apparently transferred hydrogen directly and with equal ease from NADH to both the 3-acetyl-pyridine and thionicotinamide analogues of NAD. Half-saturation values for NAD and its acetylpyridine analogue were 0.99 × 10−5 M and 3.55 × 10−4 M, respectively. The enzyme exhibited its maximum activity in phosphate buffer at pH 5.8. It was inhibited by 50–60% over the pH range 7.0–8.5 in Tris buffer. This could be reversed by dithiothreitol; reversal was complete between pH 8.0 and 8.5.

scholarly journals Pre-fermentative treatment of a model wine with aim to serve as a functional food with decreased alcohol content

2017 ◽  
Vol 63 (01) ◽  
pp. 47-53
Author(s):  
Irina Mladenoska ◽  
Verica Petkova ◽  
Tatjana Kadifkova Panovska
Keyword(s):  
Enzyme Activity ◽  
Gluconic Acid ◽  
Functional Food ◽  
Ph Value ◽  
Enzymatic Reaction ◽  
Alginate Beads ◽  
High Concentration ◽  
Ph Optimum ◽  
Enzyme Preparations ◽  
Initial Ph

The effect of substrate concentration on the enzyme activity in the reaction of glucose conversion into gluconic acid was investigated by using three different enzyme preparations in media with two different glucose concentrations. The media were simulating the conditions in the must, thus named as minimal model must, and were composed form combination of several organic acids and glucose. Those media were having initial pH of 3.5 that is a very unfavorable for glucose oxidase activity having a pH optimum at the pH value of 5.5. Among the three preparations used, the bakery additive, Alphamalt Gloxy 5080, was the most active in the medium with glucose concentration of 10 g/L, showing conversion of more than 70% for the period of 24 h, while the same enzyme preparation in the medium with 100 g/L glucose converted only about 7% of glucose. The pH value of the medium at the beginning and at the end of the enzymatic reaction was a good indicator of the enzyme activity. It seems that for the conversion of glucose in higher concentration, enzymatic preparation in high concentration should also be used. The preliminary attempt of immobilization of two preparations of glucose oxidases in alginate beads was also performed and a successful immobilization procedure for utilization in food industry was preliminarily developed. Keywords: glucose oxidases, enzymatic pretreatment, glucose, gluconic acid, model wine, functional food

scholarly journals Acetyl-CoA:4-Hydroxybutinylbithiophene O-Acetyltransferase Isoenzymes from Tagetes patula Seedlings

1987 ◽  
Vol 42 (7-8) ◽  
pp. 885-890 ◽  
Author(s):  
Gernot Metschulat ◽  
Rainer Sütfeld
Keyword(s):  
Coenzyme A ◽  
Developmental Stages ◽  
Complete Separation ◽  
Tagetes Patula ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
Acyltransferase Activity ◽  
Enzyme Preparations ◽  
Naturally Occurring ◽  
Acyl Coenzyme A

Naturally-occurring hydroxybutinylbithiophene derivatives were acylated by enzyme preparations of Tagetes patula seedlings in the presence of distinct acyl-Coenzyme A esters. The O-acyltransferase activity could only be detected after almost complete separation of the enzyme from counter-currently acting esterases which were present in the same extracts. This was achieved by affinity chromatography on Cibachron Blue A. During this procedure, the O-acyl-transferase was split, yielding two active fractions. Both had a Mr of 37,000 (±5,000), equal isoelectric properties, a pH optimum of pH 7.0, and were considerably inhibited in the presence of free Coenzyme A. Small differences existed in their affinities for their thiophenic substrates (3,4-dihydroxybutinylbithiophene and 4-hydroxybutinylbithiophene, respectively), as well as for various acyl-CoA esters as cosubstrates. With the preferred cosubstrate, acetyl-CoA, acylation took place at the 4-position of the butinyl side chain of the molecules, forming the naturally- occurring 4-acetoxybutinylbithiophene and 3-OH,4-OAc-butinylbithiophene, respectively. From the other acyl-CoA esters employed, only propionyl-CoA was likewise converted, forming the corresponding O-propionyl esters. The reactions observed are suggested to be catalyzed by two acetyl-CoA: 4-hydroxybutinylbithiophene O-acetyltransferase isoenzymes which exhibit different affinities for particular substrates and cosubstrates. The activities of both the isoenzymes changed drastically if plant material from different developmental stages was used as enzyme source. Therefore, it may be suggested that these isoenzymes play an important regulatory role in the metabolism of naturally-occurring hydroxy- and acetoxybutinylbithiophenes and their derivatives.

Studies on the enzyme phenol oxidase in a freshwater monogenetic trematode

1986 ◽  
Vol 60 (3) ◽  
pp. 201-209 ◽  
Author(s):  
A. Bhagavathiammai ◽  
K. Ramalingam
Keyword(s):  
Protocatechuic Acid ◽  
Phenol Oxidase ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Cytochemical Localization ◽  
Wide Range

AbstractCytochemical localization of the enzyme phenol oxidase inNeomurraytrema tengrahas been studied. Results reveal that the enzyme reacts with substrates such as catechol, hydroquinone, pyrogallol, dopa, doparmine, epinephrine and tyramine, but not with tyrosine and protocatechuic acid. Thus it shows activity with a wide range of phenols, aminated, mono and diphenols and also with deaminated and decarboxylated, di- and polyphenols. The maximum activity of the enzyme occurs between 40°C and 50°C with a pH optimum of 6–6.

scholarly journals Characterization of mouse liver α-l-fucosidase. Demonstration of unusual basic isoelectric forms of the enzyme that appear to be developmentally regulated

1985 ◽  
Vol 230 (1) ◽  
pp. 75-82 ◽  
Author(s):  
L D Laury-Kleintop ◽  
I Damjanov ◽  
J A Alhadeff
Keyword(s):  
Postnatal Development ◽  
Liver Enzyme ◽  
Human Liver ◽  
Mouse Liver ◽  
Kinetic Studies ◽  
Total Activity ◽  
Cross Reactivity ◽  
Ph Optimum ◽  
Neuraminidase Treatment ◽  
Mouse Tissues

Mouse tissues contain unusual basic isoelectric forms of α-L-fucosidase (with approximate isoelectric points of 8.3 and 9.0) in addition to the usual acidic and neutral forms previously described in tissues of other species. These unusual forms are very prominent in placenta and foetal tissues and comprise approx, 50-80% of total activity up to 11 days of postnatal development. By 15 days of postnatal development, the basic forms are diminished in amount and comprise not more than 25% of total activity. Neuraminidase treatment of adult mouse liver α-L-fucosidase led to significantly decreased amounts of acidic forms and increased amounts of the basic forms, suggesting that these forms are chemically related at least in part by sialic acid residues. Comparative kinetic studies on mouse liver, human liver and mouse placental α-L-fucosidases indicated that they have the same Km (0.05-0.06 mM) for 4-methylumbelliferyl α-L-fucopyranoside but different pH optima and thermostability properties. Mouse liver α-L-fucosidase has one pH optimum (5.5) and an acidic shoulder (centred around pH 4.0) compared with two distinct optima (4.3 and 6.8) for the human liver enzyme. Mouse placental α-L-fucosidase has a pH-activity curve comparable with that of the mouse liver enzyme except that the acidic shoulder is absent. Mouse liver α-L-fucosidase is considerably more thermolabile after preincubation at 50 degrees C than are the human liver and mouse placental enzymes, which gave similar thermodenaturation curves. Immunochemical studies indicated that mouse and human α-L-fucosidases are dissimilar antigenically but exhibit some cross-reactivity. The IgG fraction of antibody prepared in goat against human liver α-L-fucosidase was ineffective by itself in immunoprecipitating mouse liver α-L-fucosidase, but 63% and 72% of the mouse liver and placental enzymes respectively could be immunoprecipitated in the double-antibody experiments under conditions that immunoprecipitated 92% of the human liver enzyme.

THE INVERTASE OF THE CORN RADICLE AND ITS ACTIVITY IN SUCCESSIVE STAGES OF GROWTH

1962 ◽  
Vol 40 (1) ◽  
pp. 113-126 ◽  
Author(s):  
J. A. Hellebust ◽  
D. F. Forward
Keyword(s):  
Reducing Sugars ◽  
Sugar Content ◽  
Kinetic Studies ◽  
Invertase Activity ◽  
Cell Number ◽  
Permeability Barrier ◽  
Ph Optimum ◽  
Intact Cells ◽  
Stages Of Growth ◽  
Growing Cell

Segments of the first 10 millimeters of corn radicle tips have been analyzed in terms of invertase activity, cell number, fresh and dry weights, and sugar content. Invertase activity per cell increased 40-fold as the meristematic cell advanced to the stage of most rapid elongation, and again subsided as the cell ceased to elongate and entered the stage of maturation. In the growing cell, the concentration of sucrose remained low while that of reducing sugars increased fivefold.The corn radicle invertase was found to be a β-fructofuranosidase with a Km of 0.006 M and a pH optimum of 4.6. Kinetic studies indicate that there is no change in the nature of the corn radicle invertase during cell growth. Equivalent activities of intact cells or segments and homogenates is consistent with the assumption that the enzyme is located outside the permeability barrier of the cells.

scholarly journals The mechanism of C-20 hydroxylation of α-ecdysone in the desert locust, Schistocerca gregaria

1977 ◽  
Vol 168 (3) ◽  
pp. 513-520 ◽  
Author(s):  
P Johnson ◽  
H H Rees
Keyword(s):  
Schistocerca Gregaria ◽  
Fat Body ◽  
Difference Spectrum ◽  
Maximum Activity ◽  
Malpighian Tubules ◽  
Desert Locust ◽  
Ph Optimum ◽  
Developmental Variation ◽  
Moulting Hormone ◽  
Cytochrome P 450

1. The C-20 hydroxylation of alpha-ecdysone to produce beta-ecdysone was investigated in the desert locust, Schistocerca gregaria. 2. alpha-Ecdysone C-20 hydroxylase activity was located primarily in the fat-body and Malpighian tubules. The properties of the hydroxylation system from Malpighian tubules investigated further. 3. The enzyme system was mitochondrial, had a pH optimum of 6.5, an apparent Km of 12.5 micron and required O2 and NADPH. 4. The activity of the hydroxylation system showed developmental variation within the fifth instar, the maximum activity corresponding to the maximum tire of endogenous moulting hormone. The significance of these results is assessed in relation to the control of the endogenous titre of beta-ecdysone. 5. The mechanism of the hydroxylation system was investigated by using known inhibitors of hydroxylation reactions such as CO, metyrapone and cyanide. 6. The CO difference spectrum of the reduced mitochondrial preparation indicated the presence of cytochrome P-450 in the preparation. 7. It concluded that the alpha-ecdysone C-20 hydroxylase system is a cytochrome P-450-deendent mono-oxygenase.

scholarly journals New Hypothesis for the Molecular Mechanism of Surface-Dependent Activation of Hageman Factor (Factor XII)

1977 ◽  
Author(s):  
John H. Griffin
Keyword(s):  
Ellagic Acid ◽  
Disulfide Bonds ◽  
Kinetic Studies ◽  
Factor Xii ◽  
Reaction Products ◽  
Surface Binding ◽  
Proteolytic Activation ◽  
Hageman Factor ◽  
New Hypothesis ◽  
Dependent Mechanism

The surface-dependent mechanism of activation of highly purified human Hageman factor (HF) was studied using 3H-DFP uptake as a quantitative active site titrant. HF was treated in various ways and the reaction mixture was exposed to 3 mM 3H-DFP for 5 min at 37°. Following addition of SDS and removal of free DFP by dialysis, the reaction products were analyzed on SDS gels. In solution, the HF zymogen at 80,000 MW took up 0.015 mol DFP per mol HF. HF bound to kaolin, celite, or ellagic acid with or without high MW kininogen took up the same 0.015 mol DFP per mol HF. However, HF bound to celite or kaolin with high MW kininogen and kallikrein took up 0.9 mol DFP per mol HF into a 28,000 MW fragment of HF. In approximately half of these activated HF molecules, this 28,000 MW fragment was linked by disulfide bonds to a 52,000 MW fragment in a surface-bound 80,000 MW form of activated HF. In clotting assays, DFP did not inhibit kaolin-bound HF unless the surface-bound HF first had been proteolytically activated by kallikrein.Kinetic studies of the cleavage of 125I-HF by kallikrein or by plasmin in the presence of high MW kininogen showed that kaolin-bound HF was cleaved more than 20 times faster than HF in solution.These results suggest that binding to kaolin or celite or ellagic acid, classically known as “activating surfaces”, does not convert a detectable fraction (< 1%) of the bound HF molecules to active enzymes. Rather, surface-binding makes HF molecules much more susceptible to proteolytic activation in the presence of high MW kininogen, and the reciprocal proteolytic activations of HF and prekallikrein are thus greatly stimulated by “activating surfaces”.

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