Acta Societatis pro fauna et flora Fennica

Kielet saksa ja ruotsi.

Gender and female entrepreneurship in a pro-entrepreneurship magazine

In this working paper I discuss gendered entrepreneurship by exploring how the media writes about female entrepreneurship. The starting point is that the media when talking and writing about female entrepreneurs and female entrepreneurship, mould meanings of gender in entrepreneurship. I view entrepreneurship and gender as socially constructed, discursive phenomena. To uncover the processes of constructing gender in female entrepreneurship this paper applies a discursive framework, which treats language as a representational system producing and circulating meaning. The focus on language use as action implies that practises of writing and talking about female entrepreneurship ‘make’ gender as much as the women entrepreneurs) themselves: both involve working on culturally shared meanings to make reality intelligible. The data consists of articles published in Yrittäjä, a pro-SME magazine, in 1990-1997. In the analysis I show how gender is constructed in media talk. as a women’s issue Women entrepreneurs are constantly compared with men and with an implicitly masculine ideal of entrepreneurship and with strengths and weaknesses of women are displayed pointing out that the meaning making of gender taking place in the data refers to equality discourse. Finally I discuss possible consequences of the hegemonic equality discourse and suggest lines of further research.

Peptide hairpin nucleation with the obligatory Type I' beta-turn Aib-(D)Pro segment

The alpha-aminoisobutyric acid-D-proline (Aib-(D)Pro) dipeptide is an obligatory Type I' beta-turn forming segment that nucleates hairpin formation.

Conformations of peptides containing Z-alpha,beta-dehydroleucine (delta ZLeu). A comparison of Boc-Pro-delta ZLeu-Gly-NHEt and Boc-Pro-delta ZPhe-Gly-NHEt.

Two tripeptides of the type Boc-Pro-ΔZX-Gly-NHEt (where X = Leu, Phe) have been synthesized and their solution conformations investigated by 270 MHz 1H n.m.r. and i.r. spectroscopy. These conformational studies indicated that ΔZLeu, similar to ΔZPhe, has a strong tendency to stabilize folded Type II β-turn conformations when present at i + 2 position.

Stabilization of unusual structures in peptides using alpha,beta-dehydrophenylalanine: Crystal and solution structures of Boc-Pro-Delta Phe-Val-Delta Phe-Ala-OMe and Boc-Pro-Delta Phe-Gly-Delta Phe-Ala-OMe

The structures of two dehydropentapeptides, Boc-Pro-Delta Phe-Val-Delta Phe-Ala-OMe (I) and Boc-Pro-Delta Phe-Gly-Delta Phe-Ala-OMe (II) (Boc: t-butoxycarbonyl), have been determined by nuclear magnentic resonance (NMR), circular dichroism (CD), and X-ray, crystallographic studies. The peptide I assumes a S-shaped flat beta-bend structure, characterized by two partially overlapping type II beta-bends and absence of a second 1 <- 4 (N4-H center dot center dot center dot O1') intramolecular hydrogen bond. This is in contrast to the generally observed 3(10)-helical conformation in peptides with Delta Phe at alternate positions. This report describes the novel conformation assumed by peptide I and compares it with that of the conserved tip of the V3 loop of the HIV-1 envelope glycoprotein gp120 (sequence, G:P319 to F:P324, PDB code IACY). The tip of the V3 loop also assumes a S-shaped conformation with Arg:P322, making an intramolecular side-chain-backbone interaction with the carbonyl oxygen of Gly:P319. Interestingly, in peptide I, C(gamma)HVal(3) makes a similar side-chain-backbone C-H center dot center dot center dot O hydrogen bond with the carbonyl oxygen of the Boc group. The observed overall similarity indicates the possible use of the peptide as a viral antagonist or synthetic antigen. Peptide 11 adopts a unique turn followed by a 3(10)-helix. Both peptides I and II are classical examples of stabilization of unusual structures in oligopeptides.

Polypeptide models of collagen. II. Solution properties of (Pro-Gly-Phe)n

The conformation of (Pro-Gly-Phe)n in trifluoroethanol was investigated using CD, nmr and ir techniques. After making appropriate correction for the contribution of the phenylalanine chromophore to the observed CD spectra of the polytripeptide at several temperatures, it is found that (Pro-Gly-Phe)n can exist in a partially triple-helical conformation in this solvent a t low temperatures. The nmr and ir data support this conclusion. In conjunction with recent theoretical sutdies, our data offer an explanation for the preferential occurrence of the Phe residue in position 2 of the tripeptide sequence Gly-R2-R3, in collagen.

Diproline Templates as Folding Nuclei in Designed Peptides. Conformational Analysis of Synthetic Peptide Helices Containing Amino Terminal Pro-Pro Segments

The effect of N-terminal diproline segments in nucleating helical folding in designed peptides has been studied in two model sequences Piv-Pro-Pro-Aib-Leu-Aib-Phe-OMe (1) and Boc-Aib-Pro-Pro-Aib-Val-Ala-Phe-OMe (2). The structure of 1 in crystals, determined by X-ray diffraction, reveals a helical (RR) conformation for the segment residues 2 to 5, stabilized by one 4 -> 1 hydrogen bond and two 5 -> 1 interactions. The N-terminus residue, Pro(1) adopts a polyproline II (P-II) conformation. NMR studies in three different solvent systems support a conformation similar to that observed in crystals. In the apolar solvent CDCl3, NOE data favor the population of both completely helical and partially unfolded structures. In the former, the Pro-Pro segment adopts an alpha(R)-alpha(R) conformation, whereas in the latter, a P-II-alpha(R) structure is established. The conformational equilibrium shifts in favor of the P-II-alpha(R) structure in solvents like methanol and DMSO. A significant population of the Pro(1)- Pro(2) cis conformer is also observed. The NMR results are consistent with the population of at least three conformational states about Pro- Pro segment: trans alpha(R)-alpha(R), trans P-II-alpha(R) and cis P-II-alpha(R). Of these, the two trans conformers are in rapid dynamic exchange on the NMR time scale, whereas the interconversion between cis and trans form is slow. Similar results are obtained with peptide 2. Analysis of 462 diproline segments in protein crystal structures reveals 25 examples of the alpha(R)-alpha(R) conformation followed by a helix. Modeling and energy minimization studies suggest that both P-II-alpha(R) and alpha(R)-alpha(R) conformations have very similar energies in the model hexapeptide 1

Texts "Con and Pro" : The Early Modern Medical Controversy over Tobacco

The habit of "drinking smoke" , meaning tobacco smoking, caused a true controversy in early modern England. The new substance was used both for its alleged therapeutic properties as well as its narcotic effects. The dispute over tobacco continues the line of written controversies which were an important means of communication in the sixteenth and seventeenth century Europe. The tobacco controversy is special among medical controversies because the recreational use of tobacco soon spread and outweighed its medicinal use, ultimately causing a social and cultural crisis in England. This study examines how language is used in polemic discourse and argumentation. The material consists of medical texts arguing for and against tobacco in early modern England. The texts were compiled into an electronic corpus of tobacco texts (1577 1670) representing different genres and styles of writing. With the help of the corpus, the tobacco controversy is described and analyzed in the context of early modern medicine. A variety of methods suitable for the study of conflict discourse were used to assess internal and external text variation. The linguistic features examined include personal pronouns, intertextuality, structural components, and statistically derived keywords. A common thread in the work is persuasive language use manifested, for example, in the form of emotive adjectives and the generic use of pronouns; the latter is especially pronounced in the dichotomy between us and them. Controversies have not been studied in this manner before but the methods applied have supplemented each other and proven their suitability in the study of conflictive discourse. These methods can also be applied to present-day materials.

Structure and conformation of the calcium complex of cyclo(Ala-Leu-Pro-Gly)2 in two crystal forms

Crystal structures of two different forms of the calcium perchlorate complex of cyclo(Ala-Leu-Pro-Gly)2 have been determined and refined using X-ray crystallographic techniques. Orthorhombic form: C32H52N8O8.Ca(ClO4)2.7H2O.2CH3OH, space group C222(1), a = 14.366, b = 18.653, c = 19.824 A, Z = 4, R = 0.068 for 2208 observed reflections. Monoclinic form: C32H52N8O8.Ca(ClO4)2.4H2O, space group C2, a = 21.096, b = 10.182, c = 11.256 A, beta = 103.33 degrees, Z = 2, R = 0.075 for 2165 observed reflections. The cyclic peptide molecule in both the structures has the form of a twofold symmetric, slightly elongated bowl. Type II' beta-turns, involving Gly and Ala at the corners, exist at the two ends of the molecule. The interior of the molecule is substantially hydrophilic, and the external surface of the bowl is largely hydrophobic. The calcium ion is located at the centre of the mouth of the bowl-like molecule. In both crystal forms, four peptide carbonyl oxygens from the cyclic peptide and two solvent oxygens coordinate to the metal ion. The mode of complexation may be described as incomplete encapsulation as, for example, in the case of metal complexes of antamanide. In the crystal structures the complex ions are held together by hydrogen bonds involving perchlorate ions and water molecules. The molecular structure observed in the crystals is entirely consistent with the results of solution studies, which also indicate the conformation of the cyclic peptide in the complex to be similar to that of the uncomplexed molecule.

A novel ``pro-sensitizer'' based sensing of enzymes using Tb(III) luminescence in a hydrogel matrix

Chemically synthesized ``pro-sensitizers'' release the sensitizer in the presence of lipase or beta-glucosidase, triggering a significant luminescence response from a lanthanide based hydrogel.

Cytotoxic and pro-apoptotic effects of Abrus precatorius L. on human metastatic breast cancer cell line, MDA-MB-231

Abrus precatorius is highly regarded as a universal panacea in the herbal medicine with diverse pharmacological activity spectra. This experimental study on the mechanism of the anticancer activity of A. precatorius leaf extracts, may offer new evidence for A. precatorius in the treatment of breast cancer in clinical practice. Cell death was determined by using MTT assay. Further analyses were carried out by doing DNA laddering, PARP cleavage, FACS, semi-quantitative RT-PCR and detection of cellular reactive oxygen species (ROS) by DCFDA assay. A. precatorius showed very striking inhibition on MDA-MB-231 cells. MTT assay showed more than 75 % inhibition of the cells and treated cells indicated visible laddering pattern with thick compact band. PARP cleavage produced 89 kDa cleavage product which was associated with apoptosis. Flow cytometer exhibited a sub-G0/G1 peak as an indicative of apoptosis. mRNA expression level of apoptosis-related genes p21 and p53 was markedly increased in cells treated with the extract as compared to control. The up-regulation of p21 and p53 may be the molecular mechanisms by which A. precatorius extract which induces apoptosis. An increase in the concentration of A. precatorius extract does not generate ROS, instead it reduces ROS formation in MDA-MB-231 cells, as evident from the shift in fluorescence below untreated control. This is the first report showing that A. precatorius leaf extract exhibits a growth inhibitory effect by induction of apoptosis in MDA-MB-231 cells. Our results contribute towards validation of the A. precatorius extract as a potentially effective chemopreventive or therapeutic agent against breast cancer.

Crystal-structure analysis of cis-X-pro-containing peptidomimetics: understanding the steric interactions at cis X-pro amide bonds

Catch the twist: The cis Piv-Pro conformer (Piv=pivaloyl) of peptides is no longer inaccessible. Any cis X-Pro tertiary-amide-bond conformer can be stabilized in crystals of peptides by accommodating the unavoidable distortion of the dihedral angle of the peptide bond to the carbonyl group of the Pro residue (see picture), in this case through ni−1→πi* interactions. Steric clashes were not observed in the cis Piv-Pro rotamers studied.