Wyniki wyszukiwania

1

Controlling substrate specificity in protein kinases through chemical clamping

100%

Adams J. A.

Cellular and Molecular Biology Letters

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2005

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tom 10

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nr Suppl.2

2

Altering substrate specificity of catechol 2,3-dioxygenase from Planococcus sp. strain S5 by random mutagenesis

75%

Hupert-Kocurek K., Wojcieszynska D., Guzik U.

Acta Biochimica Polonica

|

2014

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tom 61

|

nr 4

3

Detailed characterization of the substrate specificity of mouse wax synthase

75%

Miklaszewska M., Kawinski A., Banas A.

Acta Biochimica Polonica

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2013

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tom 60

|

nr 2

Wax synthases are membrane-associated enzymes catalysing the esterification reaction between fatty acyl-CoA and a long chain fatty alcohol. In living organisms, wax esters function as storage materials or provide protection against harmful environmental influences. In industry, they are used as ingredients for the production of lubricants, pharmaceuticals, and cosmetics. Currently the biological sources of wax esters are limited to jojoba oil. In order to establish a large-scale production of desired wax esters in transgenic high-yielding oilseed plants, enzymes involved in wax esters synthesis from different biological resources should be characterized in detail taking into consideration their substrate specificity. Therefore, this study aims at determining the substrate specificity of one of such enzymes - the mouse wax synthase. The gene encoding this enzyme was expressed heterologously in Saccharomyces cerevisiae. In the in vitro assays (using microsomal fraction from transgenic yeast), we evaluated the preferences of mouse wax synthase towards a set of combinations of 11 acyl-CoAs with 17 fatty alcohols. The highest activity was observed for 14:0-CoA, 12:0-CoA, and 16:0-CoA in combination with medium chain alcohols (up to 5.2, 3.4, and 3.3 nmol wax esters/min/mg microsomal protein, respectively). Unsaturated alcohols longer than 18°C were better utilized by the enzyme in comparison to the saturated ones. Combinations of all tested alcohols with 20:0-CoA, 22:1-CoA, or Ric-CoA were poorly utilized by the enzyme, and conjugated acyl-CoAs were not utilized at all. Apart from the wax synthase activity, mouse wax synthase also exhibited a very low acyl-CoA:diacylglycerol acyltransferase activity. However, it displayed neither acyl-CoA:monoacylglycerol acyltransferase, nor acyl-CoA:sterol acyltransferase activity.

4

Polyphenol oxidase from wheat bran is a serpin

75%

Yamasaki Y., Konno H., Noda K.

Acta Biochimica Polonica

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2008

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tom 55

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nr 2

325-328

Polyphenol oxidase (PPO; EC 1.10.3.2) was isolated from wheat bran by a procedure that included ammonium sulfate fractionation, batch adsorption by DEAE-cellulofine, CM-cellulofine column chromatography, DEAE-cellulofine column chromatography, preparative isoelectric focusing, adsorption on the membrane of a Vivapure Q Maxi H spin column, and heat treatment. These procedures led to 150-fold purification with 4.2% recovery. The PPO was homogeneous by SDS/PAGE. The relative molecular weight of the PPO was estimated to be 37000 based on its mobility in SDS/PAGE. The isoelectric point of the PPO was 4.4. The Kmvalues of the PPO for caffeic acid, chlorogenic acid, pyrocatechol, 4-methyl catechol and l-DOPA as substrates were 0.077, 0.198, 1.176, 1.667 and 4.545 mM. The PPO was strongly inhibited by tropolone. The Kivalue for tropolone is 2.2 × 10–7M. The sequence of the 15 N-terminal amino-acid residues was determined to be ATDVRLSIAHQTRFA, which was identical to those of serpin from Triticum aestivum and protein Z from Hordeum vulgare. The PPO strongly inhibited the activity of trypsin, which is an enzyme of serine proteases; 50% inhibition was observed with 1.5 × 10–7M PPO. The Kivalue for PPO is 2.3 × 10–8M. The wheat bran PPO should be a very important protein for protecting wheat against disease, virus, insect and herbivore damages by both the activities of PPO and protease inhibitor.

5

The effect of cAMP and cGMP on the activity and substrate specificity of protein kinase A from methylotrophic yeast Pichia pastoris

75%

Frajnt M., Cytrynska M., Jakubowicz T.

Acta Biochimica Polonica

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2003

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tom 50

|

nr 4

Cyclic AMP dependent protein kinase (PKA) from Pichia pastoris yeast cells was found to be activated by either cAMP or cGMP. Analogs of cAMP such as 8-chloro-cAMP and 8-bromo-cAMP were as potent as cAMP in PKA activation while N6, 2'- O-dibutyryl-cAMP did not stimulate the enzyme activity. It was shown that protamine sulfate was almost equally phosphorylated in the presence of 1-2 X 10-6 M cAMP or cGMP while other substrates such as Kemptide, ribosomal protein S6 were phosphorylated to a lower extent in the presence of cGMP. It was demonstrated that pyruvate kinase is a substrate of PKA which co-purified with the P. pastoris enzyme. Moreover, pyruvate kinase was phosphorylated by PKA in the presence of cAMP and cGMP to comparable levels.

6

The occurrence of the Laboulbeniales [Fungi, Ascomycetes] in natural forest communities in the Bialowieza National Park, NE Poland

63%

Majewski T.

Fragmenta Floristica et Geobotanica

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1994

|

tom 39

|

nr 2

7

Inter organ comparison of amylases and starch content in mungbean seedlings

63%

Kaur N., Kaur P., Gupta A. K.

Acta Physiologiae Plantarum

|

2001

|

tom 23

|

nr 4

8

Prediction of substrate specificities of protein kinases

63%

Kobe B., Brinkworth R. I.

Cellular and Molecular Biology Letters

|

2005

|

tom 10

|

nr Suppl.2

9

Substrate specifity and inhibitors of polyphenol oxidase in aspect of darkening of fresh and frozen mushrooms [Agaricus bisporus [Lange] Sing.]

51%

Czapski J.

Acta Agrobotanica

|

1994

|

tom 47

|

nr 1

103-110

Activity of mushroom polyphenol oxidase (PPO) toward 6 substrates and inhibitory effect of cysteine, 2-mercaptoethanol, benzoic acid and sodium metabisulphite were determined. The o-diphenols which appeared to be the best substrates were: catechin, DOPA (L-3,4-dihydroxyphenylalanine) and chlorogenic acid. Affinity of PPO crude preparation substrates to enzyme, expressed as inverse value of Michaelis constant was lower then affinity of catechol. Inhibitory effect depended on specifity of inhibitors and their concentration. Electrophoretic patterns of PPO of mushrooms reveals slow and fast moving 4 isoforms when DOPA was used as a substrate, 2 bands for catechin and chlorogenic acid while only one band showed activity toward tyrosine and p-cresol.

10

Conserved Cys residue influences catalytic properties of potato endo-[1-3]-beta-glucanase GLUB20-2

51%

Witek A. I., Witek K., Hennig J.

Acta Biochimica Polonica

|

2008

|

tom 55

|

nr 4

791-797

The synthesis and degradation of (1->3)-β-glycosidic bonds between glucose moieties are essential metabolic processes in plant cell architecture and function. We have found that a unique, conserved cysteine residue, positioned outside the catalytic centre of potato endo-(1->3)-β-glucanase — product of the gluB20-2 gene, participates in determining the substrate specificity of the enzyme. The same residue is largely responsible for endo-(1->3)-β-glucanase inhibition by mercury ions. Our results confirm that the spatial adjustment between an enzyme and its substrate is one of the essential factors contributing to the specificity and accuracy of enzymatic reactions.

11

Substrate specificity of glucokinase and fructokinase of several conifer species

51%

Bergmann F., Mejnartowicz L.

Acta Societatis Botanicorum Poloniae

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2002

|

tom 71

|

nr 2

12

Modelling of insulin receptor tyrosine kinase in its active form: a case study for validation of theoretical methods

51%

Ginalski K., Wojciechowski M., Lesyng B.

Acta Biochimica Polonica

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1999

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tom 46

|

nr 3

An active form of an insulin receptor tyrosine kinase (IRK) catalytic core was modelled based on its experimentally known inactive form and the active form of a serine/threonine kinase, protein kinase A (PKA). This theoretical model was compared with the crystallographic structure of the active form of IRK reported later. The structures are very similar, which shows that all the most important features and interactions have been taken into account in the modelling procedure. The elaborated procedure can be applied to other tyrosine kinases. This would allow designing of a wide class of tyrosine kinase inhibitors, very important potential anti-cancer and/or anti-viral drugs.

13

Recent advances in studies on biochemical and structural properties of equilibrative and concentrative nucleoside transporters

51%

Podgorska M., Kocbuch K., Pawelczyk T.

Acta Biochimica Polonica

|

2005

|

tom 52

|

nr 4

Nucleoside transporters (NT) facilitate the movement of nucleosides and nucleobases across cell membranes. NT-mediated transport is vital for the synthesis of nucleic acids in cells that lack de novo purine synthesis. Some nucleosides display biological activity and act as signalling molecules. For example, adenosine exerts a potent action on many physiological processes including vasodilatation, hormone and neurotransmitter release, platelet aggregation, and lipolysis. Therefore, carrier-mediated transport of this nucleoside plays an important role in modulating cell function, because the efficiency of the transport processes determines adenosine availability to its receptors or to metabolizing enzymes. Nucleoside transporters are also key elements in anticancer and antiviral therapy with the use of nucleoside analogues. Mammalian cells possess two major nucleoside transporter families: equilibrative (ENT) and concentrative (CNT) Na+-dependent ones. This review characterizes gene loci, substrate specificity, tissue distribution, membrane topology and structure of ENT and CNT proteins. Regulation of nucleoside transporters by various factors is also presented.

Ograniczanie wyników

Controlling substrate specificity in protein kinases through chemical clamping

Altering substrate specificity of catechol 2,3-dioxygenase from Planococcus sp. strain S5 by random mutagenesis

Detailed characterization of the substrate specificity of mouse wax synthase

Polyphenol oxidase from wheat bran is a serpin

The effect of cAMP and cGMP on the activity and substrate specificity of protein kinase A from methylotrophic yeast Pichia pastoris

The occurrence of the Laboulbeniales [Fungi, Ascomycetes] in natural forest communities in the Bialowieza National Park, NE Poland

Inter organ comparison of amylases and starch content in mungbean seedlings

Prediction of substrate specificities of protein kinases

Substrate specifity and inhibitors of polyphenol oxidase in aspect of darkening of fresh and frozen mushrooms [Agaricus bisporus [Lange] Sing.]

Conserved Cys residue influences catalytic properties of potato endo-[1-3]-beta-glucanase GLUB20-2

Substrate specificity of glucokinase and fructokinase of several conifer species

Modelling of insulin receptor tyrosine kinase in its active form: a case study for validation of theoretical methods

Recent advances in studies on biochemical and structural properties of equilibrative and concentrative nucleoside transporters