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X-Ray Absorption Near Edge Spectroscopy of Sulfur in Biomolecules: Two Examples from Glutathione and Insulin

100%

Cinque G., Bellisola G., Colombatti M., Burattini E.

Acta Physica Polonica A

2006

vol. 109

issue 3

335-340

Although a minor constituent of cell and tissues, sulfur is an essential element to fulfil a wide range of biological processes, and it is present in the functional groups of many biomolecules that participate to redox reactions in vivo. Cysteine, one of the two S-containing aminoacids present in proteins, contains sulfur in fully reduced form and its thiol group can undergo a range of reactions under physiological conditions. X-ray absorption spectroscopy represents a unique tool to speciate the redox state of sulfur in biomolecules because of the known strong correlation between oxidation state and absorption edge energy shift (over 10 eV). Moreover, a rich X-ray absorption near edge structure is related to the chemical structures of S-containing biomolecules, as well as significant spectral changes due to biochemical action. The formation of a disulfide bond, i.e. a covalent linkage between the S atoms of two cysteine residues, or its reduction were investigated only indirectly in biomolecules. X-ray absorption spectroscopy experiments at the sulfur K-edge were performed at the soft X-ray beamline in Frascati using the wiggler source of the 0.51 GeV storage ring DAΦNE. X-ray absorption near edge structure data were collected to distinguish in situ between S-thiol and disulfide on model protein systems. Such preliminary results confirm this technique as a unique probe of sulfur chemistry in vivo. Quantitative speciation of S-metabolites can be foreseen in biological tissues with no chemical manipulations of the specimen.

Preliminary Study on Chemical Speciation of Sulphur in Cancerous Tissues

76%

Kwiatek W., Banaś A., Banaś K., Kisiel A., Cinque G., Falkenberg G.

Acta Physica Polonica A

2006

vol. 109

issue 3

383-387

Sulphur is vital for almost all living organisms by participating in a wide variety of metabolic processes. Nevertheless its biochemistry is only partially understood, due to it a few tools such as X-ray absorption near edge structure may be used to determine its chemical speciation in biological system. In this paper we focused on analysis of composition and elemental distribution in tissue structures of biological samples. We examined cancerous and non-cancerous prostate tissues. Experiments were carried out on the L-beam line at the HASYLAB, DESY (Hamburg, Germany) and DAΦNE-Light Facility at the Laboratori Nationali di Frascati (Frascati, Italy). Synchrotron radiation induced X-ray emission measurements reveal the significant differences in concentration of sulphur between cancerous and non-cancerous tissues. X-ray absorption near edge structure spectra show two main types of sulphur that are represented by X-ray peaks at 2476 eV and 2484 eV. This suggests that different sulphur components are present in the measured samples.

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2 Acta Physica Polonica A

2 2006

2 Cinque G.

1 Banaś A.

1 Banaś K.

1 Bellisola G.

1 Burattini E.

1 Colombatti M.

1 Falkenberg G.

1 Kisiel A.

1 Kwiatek W.

Search results

X-Ray Absorption Near Edge Spectroscopy of Sulfur in Biomolecules: Two Examples from Glutathione and Insulin

Preliminary Study on Chemical Speciation of Sulphur in Cancerous Tissues