Search results

1

Odwrócone struktury lipidowe i ich rola w procesach biologicznych

100%

Latowski D., Strzałka K.

|

EN

Lipids may form two main types of structures: bilayer, and inverted structures. The inverted structures can form either cylindrical inverted hexagonal structures or spherical and have inverted micelles known also as cubic phase. The type of structure formed depends on the chemical texture of lipids, degree of hydratation of their polar groups’, and several other external factors, such as pH, temperature, and presence of some chemicals or salt ions. The inverted structures play an important role in several biological processes. They can promote membrane fusion. This was applied to design of lipid based delivery systems for a lot of chemicals which have to be placed inside the cells. These structures are also used in the so-called micellar enzymology and as a new approach in homogeneous enzyme immunoassay utilizing the systems of surfactant reversed micelles in organic solvents for determination of the catalytic activity of the enzymes solubilized in such systems. Cell-free translation was also observed in reversed micelles. Some enzymes as violaxanthin de-epoxidase, protein kinase C and ATP-ase require for their activity lipids creating inverted structures. These lipids are also necessary in the transport of some proteins through membranes.

2

Violaxanthin and diadinoxanthin de-epoxidation in various model lipid systems

81%

Latowski D., Goss R., Bojko M., Strzałka K.

|

2012

|

vol. 59

|

issue 1

101-103

EN

The xanthophyll cycle is an important photoprotective process functioning in plants. One of its forms, the violaxanthin (Vx) cycle, involves interconversion between: Vx, antheraxanthin (Ax) and zeaxanthin (Zx). Another kind of the xanthophyll cycle is the diadinoxanthin (Ddx) cycle in which interconversion between Ddx and diatoxanthin (Dtx) occurs. In this study an information on molecular mechanism and regulation of these two types of the xanthophyll cycle is presented. The influence of lipids on the de-epoxidation of the xanthophyll cycle pigments was investigated, with special focus put on the significance of physical properties of the aggregates formed by inverted lipid micelles, which are necessary for activity of the xanthophyll cycle enzymes. In particular, thickness of the hydrophobic fraction of the aggregates, size of the inverted micelles, suggested by mathematical description of the structures and solubility of Vx and Ddx in various kind of lipids were studied. Obtained results show that the rate of de-epoxidation is strongly dependent on the physicochemical properties of the lipids used. The key role for enzyme activation play non-bilayer lipids and the parameters of inverted micelles such as thickness, fluidity of hydrophobic core and their diameter. The presented results show that MGDG and other non-lamellar lipids like different forms of phosphatidylethanolamine are necessary for the Vx and Ddx de-epoxidation because they provide the three-dimensional structures, which are needed for the binding of de-epoxidases and for the accessibility of Vx and Ddx to these enzymes.

3

Column chromatography as a useful step in purification of diatom pigments

71%

Tokarek W., Listwan S., Pagacz J., Leśniak P., Latowski D.

|

2016

|

vol. 63

|

issue 3

443-447

EN

Fucoxanthin, diadinoxanthin and diatoxanthin are carotenoids found in brown algae and most other heterokonts. These pigments are involved in photosynthetic and photoprotective reactions, and they have many potential health benefits. They can be extracted from diatom Phaeodactylum tricornutum by sonication, extraction with chloroform : methanol and preparative thin layer chromatography. We assessed the utility of an additional column chromatography step in purification of these pigments. This novel addition to the isolation protocol increased the purity of fucoxanthin and allowed for concentration of diadinoxanthin and diatoxanthin before HPLC separation. The enhanced protocol is useful for obtaining high purity pigments for biochemical studies.

4

Zeaxanthin epoxidation - an in vitro approach

61%

Kuczyńska P., Latowski D., Niczyporuk S., Olchawa-Pajor M., Jahns P., Gruszecki W. I., Strzałka K.

|

2012

|

vol. 59

|

issue 1

105-107

EN

Zeaxanthin epoxidase (ZE) is an enzyme operating in the violaxanthin cycle, which is involved in photoprotective mechanisms. In this work model systems to study zeaxanthin (Zx) epoxidation were developed. Two assay systems are presented in which epoxidation of Zx was observed. In these assays two mutants of Arabidopsis thaliana which have active only one of the two xanthophyll cycle enzymes were used. The npq1 mutant possesses an active ZE and is thus able to convert Zx to violaxanthin (Vx) but the violaxanthin de-epoxidase (VDE) is inactive, so that Vx cannot be converted to Zx. The other mutant, npq2, possesses an active VDE and can convert exogenous Vx to Zx under strong light conditions but reverse reaction is not possible. The first assay containing thylakoids from npq1 and npq2 mutants of A. thaliana gave positive results and high efficiency of epoxidation reaction was observed. The amount of Zx was reduced by 25%. To optimize high efficiency of epoxidation reaction additional factors facilitating both fusion of the two types of thylakoids and incorporation of Zx to their membranes were also studied. The second kind of assay contained npq1 mutant thylakoids of A. thaliana supplemented with exogenous Zx and monogalactosyldiacylglycerol (MGDG). Experiments with different proportions of Zx and MGDG showed that their optimal ratio is 1:60. In such system, due to epoxidation, the amount of Zx was reduced by 38% of its initial level. The in vitro systems of Zx epoxidation described in this paper enable analysis some properties of the ZE without necessity of its isolation.

5

Expression of three diadinoxanthin de-epoxidase genes of Phaeodacylum tricornutum in Escherichia coli Origami b and BL21 strain

61%

Bojko M., Olchawa-Pajor M., Tuleja U., Kuczyńska P., Strzałka W., Latowski D., Strzałka K.

|

2013

|

vol. 60

|

issue 4

857-860

EN

In the diadinoxanthin cycle the epoxy group is removed from diadinoxanthin and diatoxanthin is created. This conversion takes place e.g. in diatoms with the involvement of the enzyme diadinoxanthin de-epoxidase. In one of the diatom species, Phaeodactylum tricornutum (CCAP 1055/1 strain with genome sequenced) three de-epoxidase genes (PtVDE, PtVDL1, PtVDL2) have been identified, but only one of them (PtVDE) corresponds to violaxanthin de-epoxidase, an enzyme which is commonly found in higher plants. In these studies, the expression of two de-epoxidase genes of another Phaeodactylum tricornutum strain (UTEX 646), which is commonly used in diatom studies, were obtained in Origami b and BL21 E. coli strains. The molecular masses of the mature proteins are about 49 kDa and 60 kDa, respectively, for VDE and VDL2. Both enzymes are active with violaxanthin as a substrate.

6

Temperature effect on growth, and selected parameters of Phaeodactylum tricornutum in batch cultures

52%

Bojko M., Brzostowska K., Kuczyńska P., Latowski D., Olchawa-Pajor M., Krzeszowiec W., Waloszek A., Strzałka K.

|

2013

|

vol. 60

|

issue 4

861-864

EN

The effect of optimal and stress temperatures on the growth kinetics of the Phaeodactylum tricornutum CCAP/1055/1 strain (a model diatom with a known genome sequence) in batch cultures was examined. The analysis of the obtained results showed two phases of culture growth. There were significant positive correlations between OD increase of chlorophyll a chlorophyll c and protein concentration at different temperatures. The Fv/Fm parameter achieved a maximum level on the 6th or 7th day and then decreased to the values registered on the first day of observation. Genetic material undergoes gradual degradation 10 days after inoculation. The size of the cells was invariable.

Refine search results

5 Acta Biochimica Polonica

1 Kosmos

1 2016

2 2013

2 2012

1 2007

6 Latowski D.

5 Strzałka K.

3 Bojko M.

3 Kuczyńska P.

3 Olchawa-Pajor M.

1 Brzostowska K.

1 Goss R.

1 Gruszecki W. I.

1 Jahns P.

1 Krzeszowiec W.

1 Leśniak P.

1 Listwan S.

1 Niczyporuk S.

1 Pagacz J.

1 Strzałka W.

1 Tokarek W.