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1

Is aldehyde dehydrogenase inhibited by sulfur compounds? In vitro and in vivo studies

100%

Iciek M., Górny M., Bilska-Wilkosz A., Kowalczyk-Pachel D.

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2018

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vol. 65

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issue 1

125-132

EN

Aldehyde dehydrogenase (ALDH) catalyzes the critical step of ethanol metabolism, i.e. transformation of toxic acetaldehyde to acetic acid. It is a redox sensitive protein with the key Cys in its active site. Recently, it has been documented that activity of some proteins can be modified by sulfur-containing molecules called reactive sulfur species leading to the formation of hydro- persulfides. The aim of the present study was to examine whether ALDH activity can be modified in this way. Studies were performed in vitro using yeast ALDH and various reactive sulfur species, including Na2S, GSSH, K2Sx, Na2S2O3, and garlic-derived allyl sulfides. The effect of garlic-derived trisulfide on ALDH activity was also studied in vivo in the rat liver. The obtained results clearly demonstrated that ALDH could be regulated by sulfur species which inhibited its enzymatic activity. The results also suggested that not H2S but polysulfides or hydropersulfides were the oxidizing species responsible for this modification. This process was easily reversible by reducing agents. After the treatment with polysulfides or hydropersulfides the level of protein-bound sulfur increased, while the activity of the enzyme dramatically decreased. Moreover, the study demonstrated that ALDH activity was inhibited in vivo in the rat liver after garlic-derived trisulfide administration. This is the first study reporting the regulation of ALDH activity by sulfane sulfur species and the results suggest that it leads to the inhibition of the enzyme.

2

Plasma levels of total, free and protein bound thiols as well as sulfane sulfur in different age groups of rats

88%

Iciek M., Chwatko G., Lorenc-Koci E., Bald E., Włodek L.

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EN

The redox status of plasma thiols can be a diagnostic indicator of different pathological states. The aim of this study was to identify the age dependent changes in the plasma levels of total, free and protein bound glutathione, cysteine and homocysteine. The determination was conducted in plasma of three groups of rats: 1) young (3-month-old), 2) middle aged (19-month-old), and 3) old (31-month-old). Total levels of glutathione, cysteine and homocysteine and their respective free and protein-bound fractions decreased with age. The only exception was a rise in free homocysteine concentration in the middle group, which indicates a different pattern of transformations of this thiol in plasma. The drop in the level of protein-bound thiols suggests that the antioxidant capacity of plasma diminishes with age, which, consequently, leads to impaired protection of -SH groups through irreversible oxidation. The plasma sulfane sulfur level also declines with age, which means that aging is accompanied by inhibition of anaerobic sulfur metabolism.

3

Hydrogen sulfide generation from l-cysteine in the human glioblastoma-astrocytoma U-87 MG and neuroblastoma SHSY5Y cell lines

75%

Bronowicka-Adamska P., Bentke A., Wróbel M.

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2017

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vol. 64

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issue 1

171-176

EN

Hydrogen sulfide (H2S) is endogenously synthesized from l-cysteine in reactions catalyzed by cystathionine beta-synthase (CBS, EC 4.2.1.22) and gamma-cystathionase (CSE, EC 4.4.1.1). The role of 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) in H2S generation is also considered; it could be important for tissues with low CTH activity, e.g. cells of the nervous system. The expression and activity of CBS, CTH, and MPST were detected in the human glioblastoma-astrocytoma (U-87 MG) and neuroblastoma (SHSY5Y) cell lines. In both cell lines, the expression and activity of MPST were the highest among the investigated enzymes, suggesting its possible role in the generation of H2S. The RP-HPLC method was used to determine the concentration of cystathionine and alpha-ketobutyrate, products of the CBS- and CTH-catalyzed reactions. The difference in cystathionine levels between cell homogenates treated with totally CTH-inhibiting concentrations of dl-propargylglycine and without the inhibitor was used to evaluate the activity of CBS. The higher expression and activity of CBS, CTH and MPST in the neuroblastoma cells were associated with more intensive generation of H2S in the presence of 2 mM cysteine. A threefold higher level of sulfane sulfur, a potential source of hydrogen sulfide, was detected in the astrocytoma cells in comparison to the neuroblastoma cells.

4

Menadione effect on l-cysteine desulfuration in U373 cells

75%

Wróbel M., Jurkowska H.

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2007

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vol. 54

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issue 2

407-411

EN

The non-cytotoxic concentration (20 µM) of menadione (2-methyl-1,4-naphthoquinone), after 1 h of incubation, leads to loss of the activity of rhodanese by 33%, 3-mercaptopyruvate sulfurtransferase by 20%, as well as the level of sulfane sulfur by about 23% and glutathione by 12%, in the culture of U373 cells, in comparison with the control culture. Reactive oxygen species generated by menadione oxidize sulfhydryl groups in active centers of the investigated enzymes, inhibiting them and saving cysteine for glutathione synthesis. A decreased sulfane sulfur level can be correlated with an oxidative stress.

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4 Acta Biochimica Polonica

1 2018

1 2017

1 2007

1 2004

2 Iciek M.

2 Wróbel M.

1 Bald E.

1 Bentke A.

1 Bilska-Wilkosz A.

1 Bronowicka-Adamska P.

1 Chwatko G.

1 Górny M.

1 Jurkowska H.

1 Kowalczyk-Pachel D.

1 Lorenc-Koci E.

1 Włodek L.

Is aldehyde dehydrogenase inhibited by sulfur compounds? In vitro and in vivo studies

Plasma levels of total, free and protein bound thiols as well as sulfane sulfur in different age groups of rats

Hydrogen sulfide generation from l-cysteine in the human glioblastoma-astrocytoma U-87 MG and neuroblastoma SHSY5Y cell lines

Menadione effect on l-cysteine desulfuration in U373 cells