Conformation of the flexible bent helix of Leu1-zervamicin in crystal C and a possible gating action for ion passage

The membrane channel-forming polypeptide, Leu(1)-zervamicin, Ac-Leu-Ile-Gln-Iva-Ile(5)-Thr-Aib-Leu-Aib-Hyp(10) -Gln-Aib-Hyp-Aib-Pro(15)-Phol (Aib: alpha-aminoisobutyric acid; Iva: isovaline; Hyp: 4-hydroxyproline; Phol: phenylalininol) has been analyzed by x-ray diffraction in a third crystal form. Although the bent helix is quite similar to the conformations found in crystals A and B, the amount of bending is more severe with a bending angle approximate to 47 degrees, The water channel formed by the convex polar faces of neighboring helices is larger at the mouth than in crystals A and B, and the water sites have become disordered. The channel is interrupted in the middle by a hydrogen bond between the OH of Hyp(10) and the NH2 of the Gln(11) of a neighboring molecule. The side chain of Gln(11) is wrapped around the helix backbone in an unusual fashion in order that it can augment the polar side of the helix. In the present crystal C there appears to be an additional conformation for the Gln(11) side chain (with approximate to 20% occupancy) that opens the channel for possible ion passage. Structure parameters for C85H140N18O22.xH(2)O.C2H5OH are space group P2(1)2(1)2(1), a = 10.337 (2) Angstrom, b = 28.387 (7) Angstrom, c = 39.864 (11) Angstrom, Z = 4, agreement factor R = 12.99% for 3250 data observed > 3 sigma(F), resolution = 1.2 Angstrom. (C) 1994 John Wiley & Sons, Inc.

Water in Action : Encounters among 2- to 3-Year-Old Children, Adults, and Water in Day Care

In line with cultural psychology and developmental theory, a single case approach is applied to construct knowledge on how children s interaction emerge interlinked to historical, social, cultural, and material context. The study focuses on the negotiation of constraints and meaning construction among 2-to 3-year-old children, a preschool teacher, and the researcher in settings with water. Water as an element offers a special case of cultural canalization: adults selectively monitor and guide children s access to it. The work follows the socio-cultural tradition in psychology, particularly the co-constructivist theory of human development and the Network of Meanings perspective developed at the University of São Paulo. Valsiner s concepts of Zone of Free Movement and Zone of Promoted Action are applied together with studies where interactions are seen as spaces of construction where negotiation of constraints for actions, emotions, and conceptions occur. The corpus was derived at a Finnish municipal day care centre. During a seven months period, children s actions were video recorded in small groups twice a month. The teacher and the researcher were present. Four sessions with two children were chosen for qualitative microanalysis; the analysis also addressed the transformations during the months covered by the study. Moreover, the data derivation was analyzed reflectively. The narrowed down arenas for actions were continuously negotiated among the participants both nonverbally and verbally. The adults expectations and intentions were materialized in the arrangements of the setting canalizing the possibilities for actions. Children s co-regulated actions emerged in relation to the adults presence, re-structuring attempts, and the constraints of the setting. Children co-constructed novel movements and meanings in relation to the initiatives and objects offered. Gestures, postures, and verbalizations emerged from the initially random movements and became constructed to have specific meanings and functions; meaning construction became abbreviated. The participants attempted to make sense of the ambiguous (explicit and implicit) intentions and fuzzy boundaries of promoted and possible actions: individualized yet overlapping features were continuously negotiated by all the participants. Throughout the months, children s actions increasingly corresponded adults (re-defined) conceptions of water researchers as an emerging group culture. Water became an instrument and a context for co-regulations. The study contributes to discussions on children as participants in cultural canalization and emphasizes the need for analysis in early childhood education practices on the implicit and explicit constraint structures for actions.

Synthesis and exploration of novel curcumin analogues as anti-malarial agents

Curcumin, a major yellow pigment and active component of turmeric, has been shown to possess anti-inflammatory and anti-cancer activities. Recent studies have indicated that curcumin inhibits chloroquine-sensitive (CQ-S) and chloroquine-resistant (CQ-R) Plasmodium falciparum growth in culture with an IC50 of similar to 3.25 mu M (MIC = 13.2 mu M) and IC50 4.21 mu M (MIC = 14.4 mu M), respectively. In order to expand their potential as anti-malarials a series of novel curcumin derivatives were synthesized and evaluated for their ability to inhibit P. falciparum growth in culture. Several curcumin analogues examined show more effective inhibition of P. falciparum growth than curcumin. The most potent curcumin compounds 3, 6, and 11 were inhibitory for CQ-S P. falciparum at IC50 of 0.48, 0.87, 0.92 mu M and CQ-R P. falcipartan at IC50 of 0.45 mu M, 0.89, 0.75 mu M, respectively. Pyrazole analogue of curcumin (3) exhibited sevenfold higher anti-malarial potency against CQ-S and ninefold higher anti-malarial potency against CQ-R. Curcumin analogues described here represent a novel class of highly selective P. falcipartan inhibitors and promising candidates for the design of novel anti-malarial agents. (C) 2007 Elsevier Ltd. All rights reserved.

Structural plasticity and enzyme action: Crystal structures of Mycobacterium tuberculosis peptidyl-tRNA hydrolase

Peptidyl-tRNA hydrolase cleaves the ester bond between tRNA and the attached peptide in peptidyl-tRNA in order to avoid the toxicity resulting from its accumulation and to free the tRNA available for further rounds in protein synthesis. The structure of the enzyme from Mycobacteritan tuberculosis has been determined in three crystal forms. This structure and the structure of the enzyme frorn Escherichia coli in its crystal differ substantially on account of the binding of the C terminus of the E. coli enzyme to the peptide-binding site of a neighboring molecule in the crystal. A detailed examination of this difference led to an elucidation of the plasticity of the binding site of the enzyme. The peptide-binding site of the enzyme is a cleft between the body, of the molecule and a polypepticle Y stretch involving a loop and a helix. This stretch is in the open conformation when the enzyme is in the free state as in the crystals of M. tuberculosis peptidyl-tRNA hydrolase. Furthermore, there is no physical continuity between the tRNA and the peptide-binding sites. The molecule in the E. coli crystal mimics the peptide-bound enzyme molecule. The peptide stretch referred to earlier now closes on the bound peptide. Concurrently, a channel connecting the tRNA and the peptide-binding site opens primarily through the concerted movement of two residues. Thus, the crystal structure of M. tuberculosis peptidyl-tRNA hydrolase when compared with the crystal structure of the E. coli enzyme, leads to a model of structural changes associated with enzyme action on the basis of the plasticity of the molecule. (c) 2007 Elsevier Ltd. All rights reserved.

Action of N-bromosuccinimide on sperm whale myoglobin

Previously, it was reported from this laboratory that the heme groups of hemoglobin are “buried” within globin at pH 4.0 and not dissociated, on the basis of the obiligatory requirement of urea for the reaction of N-bromosuccinimide with the heme groups of hemoglobin at pH4.0, and also on the basis of the “normalization” of the spectrum of hemoglobin at this pH in the presence of urea or sucrose. In the present study, it has been shown that the behaviour of sperm whale myoglobin with respect to its reaction with N-bromosuccinimide and with respect to spectral “normalization” in urea or sucrose are essentially similar to that of hemoglobin. It has also been demonstrated that the spectral “normalization” obtained with crystalline hemin is not identical with that obtained with either hemoglobin or myoglobin. The bearing of the results of the present study on the earlier work on hemoglobin is indicated.

Action of N-bromosuccinimide on human hemoglobin and its possible bearing on heme-globin linkage

A reaction of N-bromosuccinimide with the heme groups of hemoglobin has been studied spectrophotometrically. The reaction brings about the disappearance of characteristic absorption peaks of hemoglobin and is accompanied by the release of inorganic iron from the heme groups. Urea is obligatory for the reaction to take place at pH 4.0, while it can occur in the absence of urea at pH 7.0. The spectrum of hemoglobin which does not show any peak in the Soret region at pH 4.0 is “normalized” in the presence of urea or sucrose at the same pH. The effect of “normalization” in 8 M urea is apparent over the pH range 3.0–4.5. From the obligatory requirement of urea and sucrose for “normalization” of spectrum and the dependence of the release of inorganic iron on the concentration of urea, it is suggested that heme groups are “buried” within the globin at pH 4.0 and not dissociated from globin as supposed before.

Studies in sesquiterpenes-XIX. Action of perbenzoic acid on longifolene

Oxidation of longifolene, a mono-olefinic sesquiterpene, with a chloroform solution of perbenzoic acid proceeded to almost two mole consumption of the peracid to furnish a number of products, important ones being an α-ketol, a norketone (longicamphenilone) and the corresponding C14-alcohols. Under certain conditions it has been possible to arrest the reaction at one mole consumption and to isolate longifolene-α-epoxide, which is the major product; some amounts of epimeric longifolaldehydes and longicamphenilone were also formed. Further action of perbenzoic acid on longifolene oxide and longifolaldehydes has been investigated and the results used to interpret the mechanism of abnormal peracid oxidation of longifolene.

Indoleacetaldoxime hydro-lyase (4.2.1.29). III. Further studies on the nature and mode of action of the enzyme

Further purification of indoleacetaldoxime (IAOX) hydro-lyase from Gibberella fujikuroi by DEAE-cellulose chromatography is described. The purified enzyme was activated by dehydroascorbic acid (DHA), ascorbic acid (AA), and pyridoxal phosphate (PALP) and was inhibited by thiol compounds and thiol reagents including phenylthiocyanate. Ferrous ions but not ferric ions activated the purified enzyme. The enzyme was activated by dihydrofolic acid but inhibited by tetrahydrofolic acid. Phenylacetaldoxime, a competitive inhibitor, afforded partial protection of the enzyme from the action of N-ethylmaleimide suggesting the involvement of a thiol function at the active site or substrate-binding site. The inhibition of the enzyme by 2,3-dimercaptopropanol was reversed by DHA, PALP, or frozen storage. KCN inhibition of the enzyme was reversed by PALP. NaBH4 reduction of the purified enzyme in the presence of PALP gave an active enzyme which was further activated by PALP or DHA but not by ferrous ions. These results suggested a "structural" role for PALP in the activity of IAOX hydro-lyase. Dilute solutions of the purified enzyme, obtained during DEAE-cellulose chromatography and concentrated using sucrose, showed enhanced activity upon frozen storage and thawing. The increase in activity of the enzyme during certain culture conditions, the activation and inhibition of the enzyme by several unrelated compounds, and the effect of freezing indicate that IAOX hydro-lyase is probably a metabolically regulated enzyme with a structure composed of subunits.

Transition metal complexes of 3-aryl-2-substituted 1,2-dihydroquinazolin-4(3H)-one derivatives: New class of analgesic and anti-inflammatory agents

Five-coordinate, neutral transition metal complexes of newly designed pyridine-2-ethyl-(3-carboxyhdeneamino)-3-(2-phenyl)-1,2-dihydroquinazoli n-4(3H)-one (L) were synthesized and characterized The structure of ligand is confirmed by single crystal X-ray diffraction studies The compounds were evaluated for the anti-inflammatory activity by carrageenan-induced rat paw edema model while their analgesic activity was determined by acetic acid-induced writhing test in mice wherein the transition metal complexes were found to be more active than the free ligand (C) 2010 Elsevier Masson SAS All rights reserved.

Studies in stereochemistry—I : Stereospecific routes to trans- anti- and cis- syn-Δ8-dodecahydrophenanthrenes

Reduction of trans-1-oxo-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XI) by lithium tri-t-butoxyaluminohydride gave trans-1β-hydroxy-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XII) which on lithium-liquid ammonia reduction gave trans-anti-1β-hydroxy-7-oxo-Δ8(14)-dodecahydrophenanthrene (XIII). Reduction of cis-1-oxo-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XV) by sodium borohydride gave cis-1α-hydroxy-7-methoxy-1,2,3,4,9,10,11,12-octahydrophenanthrene (XVI) which on lithium-liquid ammonia reduction gave cis-syn-1α-hydroxy-7-oxo-Δ8(14)-dodecahydrophenanthrene (XVII).

Kansalaisvaikuttamista? Habermasilaisen julkisuusteorian anti suomalaiselle ympäristöliikkeelle

Tässä pro gradu -tutkielmassa analysoidaan suomalaista ympäristöliikettä Jürgen Habermasin julkisuuden käsitteen näkökulmasta. Työn tutkimusongelmana on tarkastella julkisuutta ympäristövaikuttamisen keinona. Ponnahduslautana tutkimuksessa käytetään 2000-luvun Lapin metsien käyttöä koskevia kiistoja, joiden ratkomisyrityksiin moni Suomessa toimiva ympäristöjärjestö on osallistunut. Pitkään ratkaisemattomina olleet kiistat ovat johtaneet tilanteeseen, jossa on perusteltua kysyä, mikä ongelmien selvittämisessä on mennyt pieleen. Olisiko ennen kaikkea ammattimaiseen ja institutionalisoituneeseen vaikuttamiseen nojanneet ympäristöjärjestöt voineet toimia kiistojen yhteydessä jollakin vaihtoehtoisella tavalla? Vaihtoehdoksi esitetään Jürgen Habermasin tarjoamaa julkisuuden mallia, jonka on nähty olevan keskeinen modernin yhteiskunnan mahdollisuuksia ja rajoitteita arvioitaessa. Käsitys julkisuudesta sisältää ajatuksen kriittiseen keskusteluun pohjautuvasta, kaikille avoimesta kansalaisvaikuttamisesta. Näin muodostuneesta yleisestä mielipiteestä tulee poliittisen päätöksenteon ohjenuora. Julkisuuden ihanteen rinnalla Habermasin teoria sisältää kuvauksen julkisuuden rakennemuutoksesta – kriittisen julkisuuden alennustilasta myöhäiskapitalistisessa kulutusyhteiskunnassa. Tässä tutkimuksessa käytän näitä kahta teoreettista näkökulmaa arvioidessani nykyaikaista ympäristövaikuttamista. Keskeisin lähdeteos on Habermasin Julkisuuden rakennemuutos ja sen teoreettista perinnettä jatkaneet tutkimukset. Aineistoni koostuu kuudesta teemahaastattelusta, jotka toteutettiin keväällä 2009 Greenpeacessa, Suomen luonnonsuojeluliitossa ja WWF:ssä. Tutkimusmenetelmänä käytän teemoittelua. Sen tuloksena esiin nousevista teemoista keskeisin kertoo ympäristöjärjestöjen ammattimaistumisesta. Tulosteni mukaan ympäristövaikuttamista leimaa institutionalisoituneisuus ja hallinnollisuus, jolloin julkisuusperiaatteen toimintaedellytykset ovat heikentyneet. Julkisuuden käsitteelle löytyy kuitenkin myös varovaista tilausta suomalaisten ympäristöjärjestöjen keskuudessa.