bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability and Dynamics of Domain‐Swapped Bovine‐Seminal Ribonuclease
Authors: Chakrabarti Kalyan S. , Sanjeev B. S. , Vishveshwara Saraswathi 
Published: May 2004

AbstractThe proteins of the ribonuclease‐A (RNase‐A) family are monomeric, with the exception of bovine‐seminal ribonuclease (BS‐RNase). BS‐RNase is formed by swapping the N‐terminal helices across the two monomeric units. A molecular‐dynamics (MD) study has been performed on the protein for a simulation time of 5.5 ns to understand the factors responsible for the stability of the dimer. Essential dynamics analysis and motional correlation of the protein atoms yielded the picture of a stabilising, yet flexible, interface. We have investigated the role of intermolecular H‐bonding, protein/water interaction, and protein/water networks in stabilising the dimer. The networks of interchain H‐bonds involving side‐chain/side‐chain or side‐chain/main‐chain (ScHB) interactions between the two chains have also been studied. The ability of protein atoms in retaining particular H2O molecules was investigated as a function of the accessible surface area (ASA), depth, and hydration parameters, as well as their participation in protein/water networks.
Mutational Analysis of a Key Residue in the Substrate Specificity of a Cephalosporin Acylase
Authors: Otten Linda G. , Sio Charles F. , van der Sloot Almer M. , Cool Robbert H. , Quax Wim J. 
Published: May 2004

Abstractβ‐Lactam acylases are crucial for the synthesis of semisynthetic cephalosporins and penicillins. Unfortunately, there are no cephalosporin acylases known that can efficiently hydrolyse the amino‐adipic side chain of Cephalosporin C. In a previous directed evolution experiment, residue Asn266 of the glutaryl acylase from Pseudomonas SY‐77 was identified as being important for substrate specificity. In order to explore the function of this residue in substrate specificity, we performed a complete mutational analysis of position 266. Codons for all amino acids were introduced in the gene, 16 proteins that could be functionally expressed in Escherichia coli were purified to homogeneity and their catalytic parameters were determined. The mutant enzymes displayed a broad spectrum of affinities and activities, pointing to the flexibility of the enzyme at this position. Mutants in which Asn266 was changed into Phe, Gln, Trp and Tyr displayed up to twofold better catalytic efficiency (kcat/Km)than the wild‐type enzyme when adipyl‐7‐aminodesacetoxycephalosporanic acid (adipyl‐7‐ADCA) was used as substrate, due to a decreased Km. Only mutants SY‐77N266H and SY‐77N266M showed an improvement of both catalytic parameters, resulting in 10‐ and 15‐times higher catalytic efficiency with adipyl‐7‐ADCA, respectively. Remarkably, the catalytic activity (kcat) of SY‐77N266M when using adipyl‐7‐ADCA as substrate was as high as when glutaryl‐7‐aminocephalosporanic acid (glutaryl‐7‐ACA) was used, and approaches commercially interesting activity. SY‐77N266Q, SY‐77N266H and SY‐77N266M mutants showed a modest improvement in hydrolysing Cephalosporin C. Since these mutants also have a good catalytic efficiency when adipyl‐7‐ADCA is used and are still active towards glutaryl‐7‐ACA, they can be regarded as broad substrate acylases. These results demonstrate that the combination of directed evolution for the identification of important positions, together with saturation mutagenesis for finding the optimal amino acid, is a very effective method for finding improved biocatalysts.
Biosynthesis of Volatiles by the MyxobacteriumMyxococcus xanthus
Authors: Dickschat Jeroen S. , Wenzel Silke C. , Bode Helge B. , Müller Rolf , Schulz Stefan 
Published: May 2004

AbstractThe volatiles emitted from cell cultures of myxobacteriumMyxococcus xanthuswere collected by use of a closed‐loop stripping apparatus (CLSA) and analyzed by GC‐MS. Two new natural products, (S)‐9‐methyldecan‐3‐ol ((S)‐1) and 9‐methyldecan‐3‐one (2), were identified and synthesized, together with other aliphatic ketones and alcohols, and terpenes. Biosynthesis of the two main components (S)‐1and2was examined in feeding experiments carried out with the wild‐type strain DK1622 and two mutant strains JD300 and DK11017, which are impaired in the degradation pathway from leucine to isovaleryl‐SCoA. Isovaleryl‐SCoA is used as a starter, followed by chain elongation with two malonate units. Subsequent use of methyl malonate and decarboxylation leads to (S)‐1and2. Furthermore, 3,3‐dimethylacrylic acid (DMAA) can be used by the mutant strain to form isovaleryl‐SCoA, which corroborates recent data on the detection of a novel variety of the mevalonate pathway giving rise to isovaleryl‐SCoA from HMGCoA.
Biocatalytic Asymmetric Rearrangement of a Methylene‐Interrupted Bis‐epoxide: Simultaneous Control of Four Asymmetric Centers Through a Biomimetic Reaction Cascade
Authors: Glueck Silvia M. , Fabian Walter M. F. , Faber Kurt , Mayer Sandra F. 
Published: May 2004

AbstractAsymmetric enzyme‐catalyzed hydrolysis of methylene‐interrupted bis‐epoxides 1 a and 1 b catalyzed by bacterial epoxide hydrolases furnished tetrahydrofuran derivatives 2 a and 2 b through a hydrolysis–rearrangement cascade. Whereas racemic bis‐oxiranes 1 b–d underwent kinetic resolution with moderate stereoselectivities to yield products with up to 92 % ee and 66 % de: meso‐bis‐oxirane cis,cis‐1 a was transformed into (6R,7R,9S,10S)‐2 a in 94 % ee and 89 % de at high conversion (85 %) by Rhodococcus sp. CBS 717.73 as the major product. The reaction sequence resembles a biomimetic reaction cascade and provides an efficient entry into the structural core of annonaceous acetogenins with simultaneous control of four stereocenters.
The Immunogenicity of the Tumor‐Associated Antigen Lewisy May Be Suppressed by a Bifunctional Cross‐Linker Required for Coupling to a Carrier Protein
Authors: Buskas Therese , Li Yanhong , Boons Geert‐Jan 
Published: May 2004

AbstractA Lewisy (Ley) tetrasaccharide modified by an artificial aminopropyl spacer was synthesized by a highly convergent approach that employed a levulinoyl ester and a 9‐fluorenylmethoxycarbonate for temporary protection of the hydroxy groups and a trichloroethyloxycarbonyl as an amino protecting group. The artificial aminopropyl moiety was modified by a thioacetyl group, which allowed efficient conjugation to keyhole limpet hemocyanin (KLH) modified by electrophilic 4‐(maleimidomethyl)cyclohexane‐1‐carboxylate (MI). Mice were immunized with the KLH–MI–Ley antigen. A detailed analysis of sera by ELISA established that a strong immunoglobulin G (IgG) antibody response was elicited against the linker region. The use of a smaller and more flexible 3‐(bromoacetamido)propionate for the attachment of Ley to KLH not only reduced the IgG antibody response against the linker but also led to a significantly improved immune response against the Ley antigen. This study shows that highly antigenic linkers suppress antibody responses to weak antigens such as self‐antigens.
Heavy Alkaline Earth Metal Pyrazolates: Synthetic Pathways, Structural Trends, and Comparison with Divalent Lanthanoids
Authors: Hitzbleck Julia , O'Brien Anna Y. , Forsyth Craig M. , Deacon Glen B. , Ruhlandt‐Senge Karin 
Published: May 2004

AbstractTwo series of heavy alkaline earth metal pyrazolates, [M(Ph2pz)2(thf)4] 1 a–c (Ph2pz=3,5‐diphenylpyrazolate, M=Ca, Sr, Ba; THF=tetrahydrofuran) and [M(Ph2pz)2(dme)n] (M=Ca, 2 a, Sr, 2 b, n=2; M=Ba, 2 c, n=3; DME=1,2‐dimethoxyethane) have been prepared by redox transmetallation/ligand exchange utilizing Hg(C6F5)2. Compounds 1 a and 2 b were also obtained by redox transmetallation with Tl(Ph2pz). Alternatively, direct reaction of the alkaline earth metals with 3,5‐diphenylpyrazole at elevated temperatures under solventless conditions yielded compounds 1 a–c and 2 a–c upon extraction with THF or DME. By contrast, [M(Me2pz)2(Me2pzH)4] 3 a–c (M=Ca, Sr, Ba; Me2pzH=3,5‐dimethylpyrazole) were prepared by protolysis of [M{N(SiMe3)2}2(thf)2] (M=Ca, Sr, Ba) with Me2pzH in THF and by direct metallation with Me2pzH in liquid NH3/THF. Compounds 1 a–c and 2 a–c display η2‐bonded pyrazolate ligands, while 3 a,b exhibit η1‐coordination. Complexes 1 a–c have transoid Ph2pz ligands and an overall coordination number of eight with a switch from mutually coplanar Ph2pz ligands in 1 a,b to perpendicular in 1 c. In eight coordinate 2 a,b the pyrazolate ligands are cisoid, whilst 2 c has an additional DME ligand and a metal coordination number of ten. By contrast, 3 a,b have octahedral geometry with four η1‐Me2pzH donors, which are hydrogen‐bonded to the uncoordinated nitrogen atoms of the two trans Me2pz ligands. The application of synthetic routes initially developed for the preparation of lanthanoid pyrazolates provides detailed insight into the similarities and differences between the two groups of metals and structures of their complexes.
Separation‐Friendly Mitsunobu Reactions: A Microcosm of Recent Developments in Separation Strategies
Authors: Dandapani Sivaraman , Curran Dennis P. 
Published: May 2004

AbstractThe Mitsunobu reaction is famous for its scope and power, but infamous for its separation headaches. Typically, the target product is enticed away from the reagent‐derived byproducts by careful chromatography. The use of polymer‐bound Mitsunobu reagents solves only half of the problem, because polymer‐bound diethyl azodicarboxylate (DEAD) and phosphine reagents cannot be employed simultaneously. This article classifies, compares, and contrasts various emerging strategies for product isolation in Mitsunobu reactions. Because so many different strategies have been used, the Mitsunobu reaction is a microcosm for the new field of strategy level separations.
Vinculin is proteolyzed by calpain during platelet aggregation: 95 kDa cleavage fragment associates with the platelet cytoskeleton
Authors: Serrano Katherine , Devine Dana V. 
Published: May 2004

AbstractThe focal adhesion protein vinculin contributes to cell attachment and spreading through strengthening of mechanical interactions between cell cytoskeletal proteins and surface membrane glycoproteins. To investigate whether vinculin proteolysis plays a role in the influence vinculin exerts on the cytoskeleton, we studied the fate of vinculin in activated and aggregating platelets by Western blot analysis of the platelet lysate and the cytoskeletal fractions of differentially activated platelets. Vinculin was proteolyzed into at least three fragments (the major one being ∼95 kDa) within 5 min of platelet activation with thrombin or calcium ionophore. The 95 kDa vinculin fragment shifted cellular compartments from the membrane skeletal fraction to the cortical cytoskeletal fraction of lysed platelets in a platelet aggregation‐dependent manner. Vinculin cleavage was inhibited by calpeptin and E64d, indicating that the enzyme responsible for vinculin proteolysis is calpain. These calpain inhibitors also inhibited the translocation of full‐length vinculin to the cytoskeleton. We conclude that cleavage of vinculin and association of vinculin cleavage fragment(s) with the platelet cytoskeleton is an activation response that may be important in the cytoskeletal remodeling of aggregating platelets. Cell Motil. Cytoskeleton 58:242–252, 2004. © 2004 Wiley‐Liss, Inc.
Curcumin inhibits cell motility and alters microfilament organization and function in prostate cancer cells
Authors: Holy Jon 
Published: May 2004

AbstractCurcumin is a dietary phytochemical associated with anti‐tumorigenic effects, but the mechanisms by which it inhibits cancer cell growth and metastasis are not completely understood. For example, little information is available regarding the effects of curcumin on cytoskeletal organization and function. In this study, time‐lapse video and immunofluorescence labeling methods were used to demonstrate that curcumin significantly alters microfilament organization and cell motility in PC‐3 and LNCaP human prostate cancer cells in vitro. Curcumin rapidly arrests cell movements and subsequently alters cell shape in the highly motile PC‐3 cell line, but has a less noticeable effect on the relatively immobile LNCaP cell line. Stress fibers are augmented, and the overall quantity of f‐actin appears to increase in both types of cells following curcumin treatment. Cytochalasin B (CB) disrupts microfilament organization in both cell lines, and causes vigorous membrane blebbing in PC‐3 cells, but not LNCaP cells. Pre‐treatment of cells with curcumin suppresses changes in microfilament organization caused by CB, and blocks PC‐3 membrane blebbing. At least some of the effects of curcumin appear to be mediated by protein kinase C (PKC), as treatment with the PKC inhibitor bisindolylmaleimide inhibits the ability of curcumin to block CB‐induced membrane blebbing. These findings demonstrate that curcumin exerts significant effects on the actin cytoskeleton in prostate cancer cells, including altering microfilament organization and function. This is a novel observation that may represent an important mechanism by which curcumin functions as a chemopreventative agent, and as an inhibitor of angiogenesis and metastasis. Cell Motil. Cytoskeleton 58:253–268, 2004. © 2004 Wiley‐Liss, Inc.
Reducing the time interval between cycles using standard doses of docetaxel and lenogastrim support
Authors: Culine Stéphane , Romieu Gilles , Fabbro Michel , Becht Catherine , Cupissol Didier , Guillemare Catherine , Bleuse Jean‐Pierre , Lotz Véronique , Gourgou Sophie 
Published: May 2004

AbstractBACKGROUNDAs a single agent, 100 mg/m2 of docetaxel every 3 weeks remains the standard schedule in the first‐line treatment for metastatic disease. At this dose level, the major limiting toxicity is neutropenia. The current study was conducted to assess the feasibility of reducing time intervals between cycles while delivering standard doses of docetaxel with granulocyte–colony‐stimulating factor (G‐CSF; lenograstim).METHODSIn the first part of the study, 24 patients were randomized to receive 1 of 4 schedules: 100 mg/m2 of docetaxel every 21 days without lenograstim; 100 mg/m2 of docetaxel every 18 days with lenograstim; 100 mg/m2 of docetaxel every 14 days with lenograstim; or 100 mg/m2 of docetaxel every 10 days with lenograstim. In the second part of the study, 15 additional patients were included to confirm the feasibility of the recommended interval between cycles.RESULTSOf the 39 patients treated, 14 patients (36%) withdrew from therapy because of Grade 3 (according to standard World Health Organization criteria) nonhematologic limiting toxicities. Only 3 patients were treated in the 10‐day interval arm and were withdrawn because of toxicity—1 patient had Grade 3 asthenia after the second cycle and 2 patients had Grade 3 dermatitis after 4 cycles. Of the 24 patients treated in the 14‐day intervals, Grade 3 limiting toxicities occurred in 8 patients (33%), including dermatitis in 3 patients; diarrhea, myalgia/arthralgia, or asthenia in 4 patients; and ungual toxicity in 1 patient.CONCLUSIONSIntroduction of G‐CSF (lenograstim) as primary prophylaxis allowed the administration of docetaxel every 14 days with manageable toxicities. Further studies are now required to assess the impact in terms of response rates and survival in patients with cancer. Cancer 2004. © 2004 American Cancer Society.
Differential expression of 5HT‐1A, α1b adrenergic, CRF‐R1, and CRF‐R2 receptor mRNA in serotonergic, γ‐aminobutyric acidergic, and catecholaminergic cells of the rat dorsal raphe nucleus
Authors: Day Heidi E.W. , Greenwood Benjamin N. , Hammack Sayamwong E. , Watkins Linda R. , Fleshner Monika , Maier Steven F. , Campeau Serge 
Published: May 2004

AbstractThe dorsal raphe nucleus (DR) has a topographic neuroanatomy consistent with the idea that different parts of this nucleus subserve different functions. Here we use dual in situ hybridization to describe the rostral‐caudal neurochemical distribution of three major cell groups, serotonin (5‐hydroxytryptamine; 5‐HT), γ‐aminobutyric acid (GABA), and catecholamine, and their relative colocalization with each other and mRNA encoding four different receptor subtypes that have been described to influence DR responses, namely, 5HT‐1A, α1b adrenergic (α1b ADR), and corticotropin‐releasing factor type 1 (CRF‐R1) and 2 (CRF‐R2) receptors. Serotonergic and GABAergic neurons were distributed throughout the rostral‐caudal extent of the DR, whereas catecholaminergic neurons were generally restricted to the rostral half of the nucleus. These phenotypes essentially represent distinct cell populations, because the neurochemical markers were rarely colocalized. Both 5HT‐1A and α1b ADR mRNA were highly expressed throughout the DR, and the vast majority of serotonergic neurons expressed both receptors. A smaller percentage of GABAergic neurons also expressed 5HT‐1A or α1b ADR mRNA. Very few catecholaminergic cells expressed either 5HT‐1A or α1b ADR mRNA. CRF‐R1 mRNA was detected only at very low levels within the DR, and quantitative colocalization studies were not technically feasible. CRF‐R2 mRNA was mainly expressed at the middle and caudal levels of the DR. At midlevels, CRF‐R2 mRNA was expressed exclusively in serotonin neurons, whereas, at caudal levels, approximately half the CRF‐R2 mRNA was expressed in GABAergic neurons. The differential distribution of distinct neurochemical phenotypes lends support to the idea of functional differentiation of the DR. J. Comp. Neurol. 474:364–378, 2004. © 2004 Wiley‐Liss, Inc.
Expression ofDbx1,Neurogenin 2,Semaphorin 5A,Cadherin 8, andEmx1distinguish ventral and lateral pallial histogenetic divisions in the developing mouse claustroamygdaloid complex
Authors: Medina Loreta , Legaz Isabel , González Gertrudis , De Castro Fernando , Rubenstein John L.R. , Puelles Luis 
Published: May 2004

AbstractWe studied the lateral and ventral pallial divisions of the claustroamygdaloid complex by means of analysis of expression patterns of the developmental regulatory genesTbr1,Dbx1,Neurogenin 2,Emx1,Cadherin 8, andSemaphorin 5Ain mouse developing telencephalon, from embryonic day 12.5 until birth. Our results indicate that these genes help to distinguish distinct lateral and ventral pallial histogenetic divisions in the embryonic telencephalon.Tbr1is broadly expressed in both lateral and ventral pallial histogenetic divisions (the lateroventral migratory stream plus the mantle) during early and intermediate embryonic development; its signal becomes weak in parts of the mantle during late embryonic development.Dbx1is strongly and specifically expressed in progenitor cells (ventricular zone) of the ventral pallium during early embryonic development, but there is no signal of this gene in the rest of the pallium nor the subpallium.Neurogenin 2andSemaphorin 5Aare both expressed in a ventral subdivision of the lateroventral migratory stream (called by us the ventral migratory stream). Further, specific nuclei of the claustral complex and pallial amygdala show strong expression ofNeurogenin 2and/orSemaphorin 5A, including the ventromedial claustrum and endopiriform nuclei, the lateral and basomedial amygdalar nuclei, the anterior and posteromedial cortical amygdalar areas, plus the amygdalo‐hippocampal area. We interpret these nuclei or areas of the claustroamygdaloid complex as possible derivatives of the ventral pallium. In contrast, during embryonic development the dorsolateral claustrum, the basolateral amygdalar nucleus, and the posterolateral cortical amygdalar area do not express or show weak expression ofNeurogenin 2orSemaphorin 5A, but express selectively and stronglyCadherin 8plusEmx1, and may be derivatives of the lateral pallium. The lateral pallial and ventral pallial divisions of the claustroamygdaloid complex appear to have some different sets of connections, although this requires further investigation. J. Comp. Neurol. 474:504–523, 2004. © 2004 Wiley‐Liss, Inc.
Peptidomics of CNS‐associated neurohemal systems of adult Drosophila melanogaster: A mass spectrometric survey of peptides from individual flies
Authors: Predel Reinhard , Wegener Christian , Russell William K. , Tichy Shane E. , Russell David H. , Nachman Ronald J. 
Published: May 2004

AbstractNeuropeptides are important messenger molecules that influence nearly all physiological processes. In insects, they can be released as neuromodulators within the central nervous system (CNS) or as neurohormones into the hemolymph. We analyzed the peptidome of neurohormonal release sites and associated secretory peptidergic neurons of adult Drosophila melanogaster. MALDI‐TOF mass spectrometric analyzes were performed on single organs or cell cluster from individual flies. This first peptidomic characterization in adult fruit flies revealed 32 different neuropeptides. Peptides not directly predictable from previously cloned or annotated precursor genes were sequenced by tandem mass spectrometry. These peptides turned out to be either intermediate products of neuropeptide processing or shorter versions of known peptides. We found that the peptidome of the CNS‐associated neurohemal organs is tagma‐specific in Drosophila. Abdominal neurohemal organs and their supplying peptidergic neurons contain the capa gene products periviscerokinins and pyrokinin‐1, thoracic neurohemal organs contain FMRFamides, and the neurohemal release sites of the brain contain pyrokinin‐12‐15, pyrokinin‐2, corazonin, myosuppressin, and sNPF as their major putative release products. Our results show that peptidomic approaches are well suited to study differential neuropeptide expression or posttranslational modifications in morphologically defined parts of the nervous system and in a developmental and physiological context in animals as small as Drosophila melanogaster. J. Comp. Neurol. 474:379–392, 2004. © 2004 Wiley‐Liss, Inc.
Development and morphology of Class II Kenyon cells in the mushroom bodies of the honey bee, Apis mellifera
Authors: Farris Sarah M. , Abrams Andrew I. , Strausfeld Nicholas J. 
Published: May 2004

AbstractClass II Kenyon cells, defined by their early birthdate and unique dendritic arborizations, have been observed in the mushroom bodies of evolutionarily divergent insects. In the fruit fly Drosophila melanogaster, Class II (also called clawed) Kenyon cells are well known for their extensive reorganization that occurs during metamorphosis. The present account reports for the first time the occurrence of mushroom body reorganization during metamorphosis in holometabolous insect species outside of the Diptera. In the honey bee, Apis mellifera, Class II Kenyon cells show signs of degeneration and undergo a subtle reshaping of their axons during metamorphosis. Unlike in Drosophila, reorganization of Class II Kenyon cells in the honey bee does not involve the loss of axon branches. In contrast, the mushroom bodies of closely related hymenopteran species, the polistine wasps, undergo a much more dramatic restructuring near the end of metamorphosis. Immunohistochemistry, dextran fills, and Golgi impregnations illuminate the heterogeneous nature of Class II Kenyon cells in the developing and adult honey bee brain, with subpopulations differing in the location of dendritic arbors within the calyx, and branching pattern in the lobes. Furthermore, polyclonal antibodies against the catalytic subunit of Drosophila protein kinase A (anti‐DC0) label an unusual and previously undescribed trajectory for these neurons. The observed variations in morphology indicate that subpopulations of Class II Kenyon cells in the honey bee can likely be further defined by significant differences in their specific connections and functions within the mushroom bodies. J. Comp. Neurol. 474:325–339, 2004. © 2004 Wiley‐Liss, Inc.