Edyta Proniewicz

Neuropeptide Y and its C-terminal fragments acting on Y2 receptor: Raman and SERS spectroscopy studies

In this paper, we present spectroscopic studies of neuropeptide Y (NPY) and its native NPY(3-36), NPY(13-36), and NPY(22-36) and mutated acetyl-(Leu(28,31))-NPY(24-36)C-terminal fragments acting on Y2 receptor. Since there is some evidence for the correlation between the SERS patterns and the receptor binding ability, we performed a detailed analysis for these compounds at the metal/water interface using Raman spectroscopy (RS) and surface-enhanced Raman spectroscopy (SERS) methods. Many studies have suggested that interactions of this kind are crucial for a variety of biomedical and biochemical phenomena. The identification of amino acids in these peptide sequences by SERS allowed us to determine which molecular fragments were responsible for the interaction with the silver nanoparticle surface. Our findings demonstrated that in all of the investigated compounds, the NPY(32-36)C-terminal fragment (Thr(32)-Arg(33)-Gln(34)-Arg(35)-Tyr(36)NH2) was involved in the adsorption process onto metal substrate. The results of the present study suggest that the same molecular fragment interacts with the Y2 receptor, what proved the usefulness of the SERS method in the study of these biologically active compounds. The search for analogs acting on Y2 receptor may be important from the viewpoint of possible future clinical applications.

Study of cellulolytic enzyme immobilization on copolymers of N-vinylformamide.

This study was focused on finding of effective carriers suitable for the immobilization of cellulase. Copolymers of N-vinylformamide (NFV) and divinylbenzene (DVB) were synthesized by free radical crosslinking polymerization in inverse suspension. Methyl silicone oil was used as the continuous phase. Three polymeric carriers based on P(NVF-co-DVB) with varying degrees of crosslinking and spherical particles with different grain sizes were obtained. The formamide groups in these carriers were hydrolyzed to amino groups, yielding three P(VAm-co-DVB) polymers with vinylamine units. Enzyme, cellulase (Novozym® 476), was immobilized onto carriers with vinylamine (through glutaraldehyde) and vinylformamide groups (without glutaraldehyde). The efficiency of the enzyme immobilization was determined based on the enzymatic activity of the enzyme during the catalytic reaction relative to that of the native enzyme. All tested carriers were found to be effective carriers for the immobilization of cellulase. However, the catalytic activity of cellulase immobilized on the P(VAM-co-DVB0.27)/2000/350 carrier was higher than that for the native enzyme. In addition, two molecular spectroscopy methods, Fourier-transform absorption infrared spectroscopy (FT-IR) and Fourier-transform Raman spectroscopy (FT-Raman), were used to analyze the carriers. These studies provided complete information regarding the structure of the studied copolymers.

Pigment characterization of important golden age panel paintings of the 17th century.

Samples were obtained from two world-famous 17th century panel paintings of the Gdańsk school of panting: Seven Acts of Charity (1607, in St. Marys Church in Gdańsk, Poland) by Anton Möller and Angelic Concert (1611, in Diocesan Museum in Pelplin, Poland) by Hermann Han. Micro-Raman spectroscopy (MRS), optical microscopy (OM), and X-ray fluorescence (XRF) spectroscopy studies of the samples were performed to characterize the pigments present in the individual painting layers (a rich palette of white, black, blue, red, and yellow pigments) and the pictorial techniques used by the artists.

Interaction of bombesin and its fragments with gold nanoparticles analyzed using surface-enhanced Raman spectroscopy.

This work demonstrates the application of commercially available stable surface composed of gold nanograins with diameters ranging from 70 to 226nm deposited onto silicon wafer for surface-enhanced Raman scattering investigations of biologically active compounds, such as bombesin (BN) and its fragments. BN is an important neurotransmitter involved in a complex signaling pathways and biological responses; for instance, hypertensive action, contractive on uterus, colon or ileum, locomotor activity, stimulation of gastric and insulin secretion as well as growth promotion of various tumor cell lines, including: lung, prostate, stomach, colon, and breast. It has also been shown that 8-14 BN C-terminal fragment partially retains the biological activity of BN. The SERS results for BN and its fragment demonstrated that (1) three amino acids from these peptides sequence; i.e., l-histidine, l-methionine, and l-tryptophan, are involved in the interaction with gold coated silicon wafer and (2) the strength of these interactions depends upon the aforementioned amino acids position in the peptide sequence.

SERS characterization of neuropeptide Y and its C-terminal fragments deposited onto colloidal gold nanoparticle surface

It has been suggested that the family of neuropeptide Y (NPY) peptides is a promising target for the neuroprotective therapy; therefore, knowledge of the structure of these biologically active compounds and their behavior at solid/liquid interface is important in order to design new analogues. Because there is still a lack of detailed information on the behavior of NPY and its mutated analogues at the solid/liquid interfaces, in this work surface-enhanced Raman spectroscopy (SERS) analysis was used to investigate NPY and its native NPY3-36, NPY13-36, and NPY22-36 and mutated acetyl-(Leu28,31)-NPY24-36C-terminal fragments, acting on Y2 receptors (Y2R), in order to determine their possible metal surface/molecule interactions. In these studies, colloidal gold nanoparticle surface served as a solid surface, whereas an aqueous solution was used as a liquid medium. The observed differences in the band intensities, wavenumbers, and widths allowed us to draw conclusions on an adsorption mode of NPY and on changes in this mode upon the shortening of the peptide chain and increase in solution pH (from pH 3 to pH 11). Briefly, three different species of Tyr were identified onto the colloidal gold surface depending upon the length of the peptide chain and solution pH. Tyrosine (TyrOH) is present in a basic medium. Tyrosinate (TyrO-) is present in an acidic solution, whereas phenoxyl radical (Tyr*) appears at neutral pH for peptides having relatively short peptide chain (acetyl-(Leu28,31)-NPY24-36). The elongation of the peptide chain partially (NPY13-36 and NPY22-36) or completely (NPY3-36 and NPY) protects the Tyr residue against conversion to the radical form.