Multiple solution conformations of the integrin-binding cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-). Analysis of the (phi, psi) space available to cyclic pentapeptides

The aqueous solution structure of the cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-) has been determined by two-dimensional 1H-NMR spectroscopy, combined with a conformational search and distance-geometry calculations. As many as five conformers in slow exchange were observed, and the rate of interconversion between components was measured from the build-up rates of exchange peaks. NMR data allowed the structures of the two predominant conformers to be determined. The major component (66%) contained a cis-proline as part of a type-VIa2 beta-turn encompassing residues Asp-Val-cis-Pro-Ser. The second component (16%) contained only trans-amide bonds, and a type-VIII beta-turn formed by residues Val-Pro-Ser-D-Leu. These structures are discussed in relation to the (phi, psi), space available to the cyclic pentapeptide, determined by a conformational search, and in relation to previously published cyclic-pentapeptide structures. The molecule exhibits activity in a scintillation-proximity assay for the inhibition of the interaction between the integrin very-late antigen-4 (VLA-4; alpha 4 beta 1) and vascular-cell-adhesion molecule-1 (VCAM-1). The structure/activity relationship of the LDV sequence is discussed and related to the recently published X-ray structure of VCAM-1. The relevance of the work to the design of anti-inflammatory drugs is discussed.     

The role in cell binding of a beta-bend within the triple helical region in collagen alpha 1 (I) chain: structural and biological evidence for conformational tautomerism on fiber surface

Dystrophin is a plasma membrane-associated cytoskeletal protein of the spectrin superfamily. The dystrophin cytoskeleton has been first characterized in muscle. Muscular 427 kDa dystrophin binds to subplasmalemmal actin filaments via its amino-terminal domain. The carboxy-terminus of dystrophin binds to a plasma membrane anchor, beta-dystroglycan, which is associated on the external side with the extracellular matrix receptor, alpha-dystroglycan, that binds to the basal lamina proteins laminin-1, laminin-2, and agrin. In the muscle, the dystroglycan complex is associated with the sarcoglycan complex that consists of several glycosylated, integral membrane proteins. The absence or functional deficiency of the dystrophin cytoskeleton is the cause of several types of muscular dystrophies including the lethal Duchenne muscular dystrophy (DMD), one of the most severe and most common genetic disorders of man. The dystrophin complex is believed to stabilize the plasma membrane during cycles of contraction and relaxation. Muscular dystrophin and several types of dystrophin variants are also present in extramuscular tissues, e.g. in distinct regions of the central nervous systems including the retina. Absence of dystrophin from these sites is believed to be responsible for some extramuscular symptoms of DMD, e.g. mental retardation and disturbances in retinal electrophysiology (reduced b-wave in electroretinograms). The reduced b-wave in electroretinograms indicated a disturbance of neurotransmission between photoreceptors and ON-bipolar cells. At least two different dystrophin variants are present in photoreceptor synaptic complexes. One of these dystrophins (Dp260) is virtually exclusively expressed in the retina. In the neuroretina, dystrophin is found in significant amounts in the invaginated photoreceptor synaptic complexes. At this location dystrophin colocalizes with dystroglycan. Agrin, an extracellular ligand of alpha-dystroglycan, is also present at this location whereas the proteins of the sarcoglycan complex appear to be absent in photoreceptor synaptic complexes. Dystrophin and dystroglycan are located distal from the ribbon-containing active synaptic zones where both proteins are restricted to the photoreceptor plasma membrane bordering on the lateral sides of the synaptic invagination. In addition, some neuronal profiles of the postsynaptic complex also contain dystrophin and beta-dystroglycan. These profiles appear to belong at least in part to projections of the photoreceptor terminals into the postsynaptic dendritic complex. In view of the abnormal neurotransmission between photoreceptors and ON-bipolar cells in DMD patients the dystrophin/beta-dystroglycan-containing projections of photoreceptor presynaptic terminals into the postsynaptic dendritic plexus might somehow modify the ON-bipolar pathway. Another retinal site associated with dystrophin/beta-dystropglycan is the plasma membrane of Müller cells where dystrophin/beta-dystroglycan appear to be present at particular high concentrations. At this location the dystrophin/dystroglycan complex may play a role in the attachment of the retina to the vitreous, and, under pathological conditions, in traction-induced retinal detachment.     

MetateM: An introduction

In this paper a methodology for the use of temporal logic as an executable imperative language is introduced. The approach, which provides a concrete framework, calledMetateM, for executing temporal formulae, is motivated and illustrated through examples. In addition, this introduction provides references to further, more detailed, work relating to theMetateM approach to executable logics.     

Conifers and commemoration — the politics and protocol of planting

This study examines the symbolic role of trees, shrubs and flowers on 20th century battle grounds and military cemeteries. By focusing on the imagery of commemoration and on the power of horticultural symbols the paper explores the emergence of an iconography during wartime and its perpetuation in ritualized peacetime landscapes. The paper makes specific reference to the Western Front in France and Belgium, and to the consecrated ground of the Dardanelles peninsula — a commemorative terrain that is being altered by Turkish planting and memorial schemes that are bringing into sharp focus the problems of maintaining Christian burial grounds in perpetuity across the globe. The paper concludes by asking whether tree planting may have replaced memorial building in the rhetoric and culture of commemoration.     

The Rǒle of Starch in Baked Goods Part 2. The Influence of Purification Procedure on the Surface Properties of the Granule

Starch was extracted from wheat by a wet-grinding process and purified by differential centrifugation followed by shaking with toluene and water. The contrast in pasting, surface and baking properties between dried impure, and dried purified, samples of the starches shows that the surface properties of the granules are profoundly affected by the presence of indigenous “non-starch material”. These effects can be eliminated by utilizing the non-dried starch, or by removing such non-starch material by shaking with toluene prior to drying the granules.     

Scanning Electron Microscopy of Wheat Starch. IV. Digestion of large Granules by Glucoamylase of Fungal (Aspergillus niger) Origin)

Starch granules attacked by glucoamylase of fungal origin show a pattern of erosion which is different from that resulting from wheat alpha-amylase attack. The glucoamylase pattern, which is characterised by a relatively uniform erosion of the surface is discussed in comparison with that of alpha-amylase and possible reasons for the differences are suggested.     

Book reviews

Landscape Transformed

London, Academy Editions, 1996, 112 pp., no price given, ISBN 1-85490-452-3

Sculpting with the Environment: a natural dialogue

Baile Oakes (Ed.)

New York, Van Nostrand Reinhold, 1995, ISBN 0-442-01642-5, 252 pp., £45.00, hb.

After the Ruins: restoring the countryside of Northern France after the Great War

Hugh Clout

Exeter, University of Exeter Press, 1996, ISBN 0-85989-491-6,332 pp., £35.

Environmental Aesthetics: ideas, politics and planning

J. Douglas Porteous

London and New York, Routledge, 1996, ISBN 0-415-13769-1, 20 pp., £15.99.

Countryside Survey 1990 Main Report

C.J. Barr, R.G.H. Bunce, R.T. Clarke, R.M. Fuller, M.T. Furse, M.K. Gillespie, G.B. Groom, C.J. Hallam, M. Hornung, D.C. Howard & M.J. Ness

London, Department of the Environment, 1993, 174 pp., £12.00 (available from DoE Publications Sales Unit, Block 3, Spur 2, Government Buildings, Lime Grove, Eastcote, HA4 8SE)

World of Environmental Design, Volume 1: Urban Spaces I (Streets and Squares)

Francisco Asenio Cerver

Barcelona, Arco Editorial, 1995, 255 pp., US$75 (per volume) ISBN 84-8185-004-7 (complete work), ISBN 84-8185-005-5 (Volume 1)

'The Remains of Distant Times': archaeology and the National Trust

David Morgan Evans, Peter Salway & David Thackray (Eds)

Woodbridge, Suffolk, The Boydell Press, 1996, ISBN 0-85115-671-1, hb, 235 pp., £29.50

Apostle of Taste: Andrew Jackson Downing 1815-1852

D. Schuyler

Baltimore, fohns Hopkins University Press, 1996, ISBN 0-8018-5229-3, $35.95