scholarly journals Control of 5-aminolaevulinate synthetase activity in Rhodopseudomonas spheroides. The purification and properties of an endogenous activator of the enzyme

1973 ◽  
Vol 136 (3) ◽  
pp. 491-499 ◽  
Author(s):  
Albert Neuberger ◽  
John D. Sandy ◽  
George H. Tait
Keyword(s):  
Pyridoxal Phosphate ◽  
Sodium Succinate ◽  
Active Form ◽  
Low Molecular Weight ◽  
Synthetase Activity ◽  
Temperature Dependent ◽  
Endogenous Factors ◽  
Ph Values ◽  
Purification And Properties ◽  
Rhodopseudomonas Spheroides

1. A low-molecular-weight activator of 5-aminolaevulinate synthetase was detected in extracts of Rhodopseudomonas spheroides. The compound activates the enzyme extracted from oxygenated semi-anaerobically grown organisms by a factor of 6–8. 2. The activator was extensively purified, but owing to the exceedingly small amounts that could be extracted in the active form its structure was not determined. 3. The activator contains an acetylatable amino group; it is more stable at acid than at alkaline pH values; it is stable to treatment with I2–KI or potassium ferricyanide, but irreversibly inactivated by Na2S2O4 or NaBH4. 4. The chromatographic, electrophoretic, chemical and stability properties of the activator are similar to those of pteridines; purified activator preparations contain pteridines, as shown by their fluorescence spectrum. This does not, however, constitute an identification of the activator. 5. The activator enhances the activity of crude and partially purified enzyme and does not appear to require other endogenous factors or a supply of air to produce activation. Activation of the purified enzyme, however, requires the presence of either pyridoxal phosphate or sodium succinate. In the absence of both these factors the activator produces a time- and temperature-dependent decay of activity.

scholarly journals Control of 5-aminolaevulinate synthetase activity in Rhodopseudomonas spheroides. Binding of pyridoxal phosphate to 5-aminolaevulinate synthetase

1979 ◽  
Vol 177 (2) ◽  
pp. 661-671 ◽  
Author(s):  
R C Davies ◽  
A Neuberger
Keyword(s):  
Schiff Base ◽  
High Activity ◽  
Pyridoxal Phosphate ◽  
Enzymic Activity ◽  
Synthetase Activity ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Active Centre ◽  
Rhodopseudomonas Spheroides ◽  
Low Activity

1. Pyridoxal 5′-phosphate is a cofactor essential for the enzymic activity of aminolaevulinate synthetase from Rhodopseudomonas spheroides. It also aids activation of the low-activity enzyme by trisulphides such as cystine trisulphide, whereas inactivation of enzyme is facilitated by its absence. 2. The fluorescence spectrum of purified high-activity enzyme is that expected for a pyridoxal phosphate–Schiff base, but the firmly bound cofactor does not appear to be at the active centre. In dilute solutions of enzyme this grouping is inaccessible to nucleophiles such as glycine, hydroxylamine, borohydride and cyanide, at pH 7.4. 3. An active-centre Schiff base is formed between enzyne and added pyridoxal phosphate, which is accessible to nucleophiles. Concentrated solutions of this enzyme–Schiff base on treatment with glycine yield apo- and semi-apoenzyme, which can re-bind pyridoxal phosphate. 4. Two types of binding of pyridoxal phosphate are distinguishable in dilute solution of enzyme, but these become indistinguishable when concentrated solutions are treated with cofactor. A change occurs in the susceptibility towards borohydride of the fluorescence of the “structural” pyridoxal phosphate. 5. One or two molecules of cofactor are bound per subunit of mol. wt. 50 000 in semiapo- or holo-enzyme. The fluorescence of pyridoxamine phosphate covalently bound to enzyme also indicates one to two nmol of reducible Schiff base per 7000 units of activity in purified and partially purified samples of enzyme. 6. Cyanide does not convert high-activity into low-activity enzyme, but with the enzyme-pyridoxal phosphate complex it forms a yellow fluorescent derivative that is enzymically active.

scholarly journals The purification and properties of two staphylolytic enzymes from Streptomyces griseus

1968 ◽  
Vol 106 (1) ◽  
pp. 69-76 ◽  
Author(s):  
J. B. Ward ◽  
H R Perkins
Keyword(s):  
Molecular Weight ◽  
Cell Walls ◽  
Teichoic Acid ◽  
Streptomyces Griseus ◽  
Low Molecular Weight ◽  
Whole Cells ◽  
Ph Values ◽  
Purification And Properties ◽  
Soil Isolate ◽  
Isolated Cell

1. Two staphylolytic enzymes have been purified from cultures of a soil isolate of Streptomyces griseus. 2. The purified enzymes were shown to be basic proteins of low molecular weight. Each enzyme released N-acetylmuramic acid reducing groups from the cell walls of Staphylococcus aureus. 3. The enzymes lysed whole staphylococci best at higher pH values and lower ionic strengths than when the substrate was isolated cell walls or purified mucopeptide. 4. Added teichoic acid did not inhibit the enzymes, but it formed an ethanol-precipitable complex with them. 5. The possibility that teichoic acid on the surface of whole cells prevents the access of the enzymes to their mucopeptide substrate is discussed.

scholarly journals Control of δ-aminolaevulate synthetase activity in Rhodopseudomonas spheroides

1969 ◽  
Vol 111 (4) ◽  
pp. 385-394 ◽  
Author(s):  
J. Marriott ◽  
A. Neuberger ◽  
G. H. Tait
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Synthetase Activity ◽  
Heat Stable ◽  
Cell Extracts ◽  
Spontaneous Activation ◽  
Effect Of Oxygen ◽  
Rhodopseudomonas Spheroides ◽  
No Activation

1. δ-Aminolaevulate synthetase from Rhodopseudomonas spheroides grown semi-anaerobically undergoes a spontaneous activation during the first hour after the disruption of cells when homogenates are stored at 4°. 2. After cultures of R. spheroides growing semi-anaerobically are oxygenated no activation of δ-aminolaevulate synthetase occurs in cell extracts. Cessation of activation in extracts is almost complete 10min. after oxygenation of cells has begun. 3. A heat-stable fraction of low molecular weight from semi-anaerobic cells reactivates δ-aminolaevulate synthetase in extracts of oxygenated cells and appears to contain a compound responsible for the spontaneous activation. 4. A heat-stable fraction of low molecular weight from oxygenated cells inhibits the spontaneous activation in extracts of semi-anaerobic cells. 5. The effect of oxygen on the rate of bacteriochlorophyll synthesis in R. spheroides may be mediated through alterations in the concentrations of a low-molecular-weight activator and inhibitor of δ-aminolaevulate synthetase.

scholarly journals Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3719
Author(s):  
Ana Catarina Sousa ◽  
Lígia O. Martins ◽  
M. Paula Robalo
Keyword(s):  
Membered Ring ◽  
Low Molecular Weight ◽  
Redox Potentials ◽  
Redox Mediators ◽  
Multicopper Oxidases ◽  
Phenothiazine Derivatives ◽  
Ph Values ◽  
Electron Shuttles ◽  
Specific Oxidation ◽  
Optimal Ph

Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.

Temperature dependent measurements on a low-molecular-weight photorefractive glass

2002 ◽  
Author(s):  
Ralf Bausinger ◽  
Andre Leopold ◽  
Stephan J. Zilker ◽  
Dietrich Haarer ◽  
Jolita Ostrauskaite ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
Temperature Dependent

scholarly journals Specificity and properties of the nucleotide carrier in chromaffin granules from bovine adrenal medulla

1983 ◽  
Vol 210 (3) ◽  
pp. 789-794 ◽  
Author(s):  
A Weber ◽  
E W Westhead ◽  
H Winkler
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Pyridoxal Phosphate ◽  
Chromaffin Granules ◽  
Inhibitory Effects ◽  
Temperature Dependent ◽  
Arginine Residues ◽  
Disulphonic Acid ◽  
Important Position ◽  
Broad Specificity

1. The influence of various substances on the uptake of [3H]ATP and [14C]-noradrenaline into isolated bovine chromaffin granules was investigated. The carrier-mediated [3H]ATP uptake is specifically inhibited by SO42-, PO43- and phosphoenolpyruvate. Compounds with carboxylic acid or sulphonic acid groups had no significant inhibitory effects on either uptake. 2. 35SO42-, 32PO43- and phosphoenol[14C]pyruvate are taken up into chromaffin granules by a temperature-dependent process that is inhibited by atractyloside, uncouplers of oxidative phosphorylation and lipid-permeant anions. The apparent Km of 35SO42- uptake is 0.4 mM. 3. These results indicate that the nucleotide carrier in chromaffin granules has a broad specificity, transporting compounds with two strong negative charges. 4. Amino acid probes influence the uptake of ATP and catecholamines differently. Pyridoxal phosphate inhibits both uptake processes, 4,4′-di-isothiocyanostilbene-2,2′-disulphonic acid preferentially blocks ATP uptake, whereas phenylglyoxal blocks only ATP transport. It is suggested that the nucleotide carrier possesses arginine residues in a functionally important position. 5. The significance of these results obtained on isolated granules for the function of chromaffin granules within the cell is discussed.

scholarly journals The interrelations between high- and low-molecular-weight forms of normal and mutant (Krabbe-disease) galactocerebrosidase

1980 ◽  
Vol 189 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Yoav Ben-Yoseph ◽  
Melinda Hungerford ◽  
Henry L. Nadler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Krabbe Disease ◽  
Low Molecular Weight ◽  
Molecular Weight Form

Galactocerebrosidase (β-d-galactosyl-N-acylsphingosine galactohydrolase; EC 3.2.1.46) activity of brain and liver preparations from normal individuals and patients with Krabbe disease (globoid-cell leukodystrophy) have been separated by gel filtration into four different molecular-weight forms. The apparent mol.wts. were 760000±34000 and 121000±10000 for the high- and low-molecular-weight forms (peaks I and IV respectively) and 499000±22000 (mean±s.d.) and 256000±12000 for the intermediate forms (peaks II and III respectively). On examination by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the high- and low-molecular-weight forms revealed a single protein band with a similar mobility corresponding to a mol.wt. of about 125000. Antigenic identity was demonstrated between the various molecular-weight forms of the normal and the mutant galactocerebrosidases by using antisera against either the high- or the low-molecular-weight enzymes. The high-molecular-weight form of galactocerebrosidase was found to possess higher specific activity toward natural substrates when compared with the low-molecular-weight form. It is suggested that the high-molecular-weight enzyme is the active form in vivo and an aggregation process that proceeds from a monomer (mol.wt. approx. 125000) to a dimer (mol.wt. approx. 250000) and from the dimer to either a tetramer (mol.wt. approx. 500000) or a hexamer (mol.wt. approx. 750000) takes place in normal as well as in Krabbe-disease tissues.

A new software of calculating the pH values of coastal seawater: Considering the effects of low molecular weight organic acids

2019 ◽  
Vol 211 ◽  
pp. 108-116 ◽  
Author(s):  
Li-Na Lyu ◽  
Daoming Lu ◽  
Chengjun Sun ◽  
Haibing Ding ◽  
Liang-Min Yu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Acids ◽  
Low Molecular Weight ◽  
Coastal Seawater ◽  
Ph Values

Possible Mechanisms for the Increase in Alkaline Phosphatase Activity of Lyophilized Control Material

1972 ◽  
Vol 18 (12) ◽  
pp. 1518-1523 ◽  
Author(s):  
Alistair F Smith ◽  
Barbara A Fogg
Keyword(s):  
Molecular Weight ◽  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Gel Filtration ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Control Material ◽  
Rate Of Increase ◽  
Control Procedures

Abstract The increased alkaline phosphatase (EC 3.1.3.1) activity of reconstituted lyophilized control sera has recently been the focus of considerable interest because of its possible implications for quality-control procedures. We confirm that these reconstituted materials show a temperature-dependent increase in alkaline phosphatase activity, but could show no alteration in activity of fresh sera. The rate of increase in activity was unaffected by dialysis of the reconstituted material, and occurred more rapidly in dilute solutions. Studies with acrylamide gel electrophoresis and Sephadex G-200 gel filtration showed that, immediately after reconstitution, a high-molecular-weight alkaline phosphatase component predominated; during subsequent spontaneous activation this component decreased, and there was a concomitant increase in a low-molecular-weight alkaline phosphatase component. The results obtained when the reconstituted material was extracted with butanol suggest that the observed changes in alkaline phosphatase activity may be attributed to the breakdown of a complex between alkaline phosphatase and lipoprotein.

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