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  • Chemistry  (802)
  • ASTROPHYSICS  (208)
  • Life Sciences (General)  (198)
  • Life and Medical Sciences  (84)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 695-715 
    ISSN: 0192-8651
    Keywords: nucleic acid ; multivariate analysis ; Ramachandran plots ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method to construct the equivalent of multidimensional Ramachandran plots for nucleic acids on the basis of singular value decomposition (SVD) is presented. For this purpose, a data matrix containing 244 DNA dinucleoside monophosphate steps, represented by nine torsion angles, was decomposed into a score and loading matrix. It is shown that biplots, containing both score points and loading vectors, provide a simple tool to interpret the principles of DNA class separation. Scores separate the data matrix into one A-DNA class, two different B-DNA classes, and one so-called crankshaft class. Loading vectors correlate torsion angles. The projections of scores on loading vectors indicate which torsion angles play a dominant role in DNA class separation. The results of the biplots are supported by (simple) physical interpretations. From a three-dimensional score space the nine original torsion angles can be reconstructed. Hence, the potential to create the multidimensional equivalent of a Ramachandran plot is available; that is, forbidden and accessible regions in the reduced space reflect these same regions in the nine-dimensional original space.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 695-715, 1998
    Additional Material: 12 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1031-1042 
    ISSN: 0006-3592
    Keywords: peptide synthesis ; alcohol ; chemical modification ; α-chymotrypsin ; reverse micelles ; response ; surface methodology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the long chain alcohols, hexanol, octanol, and decanol, as cosurfactants of the reverse micellar system of tetradecyltrimethylammonium bromide on the α-chymotrypsin-mediated AcPheLeuNH2 synthesis was studied. The effect of temperature, buffer molarity, pH, and substrate concentration was also evaluated. The enzyme was chemically modified and the effect of this modification upon the enzyme activity was also analyzed. Octanol allowed a higher activity for both enzyme forms. The peptide synthesis/substrate hydrolysis ratio is independent of the long chain alcohol used. The chemical modification decreases the α-chymotrypsin activity under the system conditions studied, but increases the initial velocity of peptide synthesis relative to the ester substrate hydrolysis. The response surface methodology was applied to optimize the dipeptide synthesis in the system containing octanol as cosurfactant. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Increasing evidence suggests that transforming growth factor-β (TGF-β) is involved in bone formation during remodeling. Using a recently cloned human leukemic cell line (FLG 29.1 cells) we demonstrate that these cells synthesize and secrete TGF-β1 and that exogenous or autocrine TGF-β1 can induce the same features of osteoclastic-like cells, exerting its effects through the binding to TGF-β specific receptors. Scatchard analysis of 125I-labeled TGF-β1 to FLG 29.1 cells revealed the presence of a single high affinity binding site with a Kd value of ∼25 pM and a binding capacity of ∼900 sites/cell. Affinity labeling experiments showed that FLG 29.1 cells express type I and type II TGF-β receptors. Stimulation of FLG 29.1 cells with low TGF-β1 doses reduced cell proliferation and increased cell adhesion and tartrate resistant acid phosphatase (TRAcP) activity. Pretreatment of FLG 29.1 cells with TGF-β1 caused a significant and dose-dependent response to calcitonin. Northern blot of total mRNA and analysis of the conditioned media (CM) showed that TGF-β1 was synthesized by FLG 29.1 cells. TPA treatment, which induces partial differentiation of these cells, markedly increased TGF-β1 mRNA expression and growth factor release. The majority of TGF-β1 secreted by TPA-treated cells was in its latent form. However, anti-TGF-β antibodies inhibited TGF-β1 and TPA-induced growth inhibition, calcitonin responsiveness, and TRAcP activity, suggesting that the TPA effect is mediated in part by autocrine TGF-β1 and indicating that the cells can activate and respond to the TGF-β that they secrete. These findings support a potential autocrine role for TGF-β1 in osteoclast differentiation. © 1994 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
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  • 4
    Publication Date: 2019-07-13
    Description: Because both abscisic acid (ABA) and auxin (IAA) have been suggested as possible chemical mediators of differential growth during root gravitropism, we compared with redistribution of label from applied 3H-IAA and 3H-ABA during maize root gravitropism and examined the relative basipetal movement of 3H-IAA and 3H-ABA applied to the caps of vertical roots. Lateral movement of 3H-ABA across the tips of vertical roots was non-polar and about 2-fold greater than lateral movement of 3H-IAA (also non-polar). The greater movement of ABA was not due to enhanced uptake since the uptake of 3H-IAA was greater than that of 3H-ABA. Basipetal movement of label from 3H-IAA or 3H-ABA applied to the root cap was determined by measuring radioactivity in successive 1 mm sections behind the tip 90 minutes after application. ABA remained largely in the first mm (point of application) whereas IAA was concentrated in the region 2-4 mm from the tip with substantial levels found 7-8 mm from the tip. Pretreatment with inhibitors of polar auxin transport decreased both gravicurvature and the basipetal movement of IAA. When roots were placed horizontally, the movement of 3H-IAA from top to bottom across the cap was enhanced relative to movement from bottom to top whereas the pattern of movement of label from 3H-ABA was unaffected. These results are consistent with the hypothesis that IAA plays a role in root gravitropism but contrary to the idea that gravi-induced asymmetric distribution of ABA contributes to the response.
    Keywords: Life Sciences (General)
    Type: Plant growth regulation (ISSN 0167-6903); 20; 253-8
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  • 5
    Publication Date: 2019-07-13
    Description: We compared the kinetics of auxin redistribution across the caps of primary roots of 2-day-old maize (Zea mays, cv Merit) seedlings with the time course of gravitropic curvature. [3H] indoleacetic acid was applied to one side of the cap in an agar donor and radioactivity moving across the cap was collected in an agar receiver applied to the opposite side. Upon gravistimulation the roots first curved upward slightly, then returned to the horizontal and began curving downward, reaching a final angle of about 67 degrees. Movement of label across the caps of gravistimulated roots was asymmetric with preferential downward movement (ratio downward/upward = ca. 1.6, radioactivity collected during the 90 min following beginning of gravistimulation). There was a close correlation between the development of asymmetric auxin movement across the root cap and the rate of curvature, with both values increasing to a maximum and then declining as the roots approached the final angle of curvature. In roots preadapted to gravity (alternate brief stimulation on opposite flanks over a period of 1 hour) the initial phase of upward curvature was eliminated and downward bending began earlier than for controls. The correlation between asymmetric auxin movement and the kinetics of curvature also held in comparisons between control and preadapted roots. Both downward auxin transport asymmetry and downward curvature occurred earlier in preadapted roots than in controls. These findings are consistent with suggestions that the root cap is not only the site of perception but also the location of the initial redistribution of effectors that ultimately leads to curvature.
    Keywords: Life Sciences (General)
    Type: Plant physiology (ISSN 0032-0889); 92; 792-6
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  • 6
    Publication Date: 2019-08-15
    Description: We examined the effect of calmodulin (CaM) antagonists applied at the root tip on root growth, gravity-induced root curvature, and the movement of calcium across the root tip and auxin (IAA) across the elongation zone of gravistimulated roots. All of the CaM antagonists used in these studies delayed gravity-induced curvature at a concentration (1 micromole) that did not affect root growth. Calmodulin antagonists (〉 or = 1 micromole) inhibited downward transport of label from 45Ca2+ across the caps of gravistimulated roots relative to the downward transport of 45Ca2+ in gravistimulated roots which were not treated with CaM antagonists. Application of CaM antagonists at the root tip (〉 or = 1 micromole) also decreased the relative downward movement of label from 3H-IAA applied to the upper side of the elongation zone of gravistimulated roots. In general, tip application of antagonists inhibited neither the upward transport of 45Ca2+ in the root tip nor the upward movement of label from 3H-IAA in the elongation zone of gravistimulated roots. Thus, roots treated with CaM antagonists 〉 or = 1 micromole become less graviresponsive and exhibit reduced or even a reversal of downward polarity of calcium transport across the root tip and IAA transport across the elongation zone. The results indicate that calmodulin-regulated events play a role in root gravitropism.
    Keywords: Life Sciences (General)
    Type: Plant growth regulation (ISSN 0167-6903); 11; 4; 419-27
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 599-602 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 170-172 
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; Gas chromatography ; LC/GC ; On-line coupling ; Metal complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The on-line coupled LC-GC technique was applied to the analysis of several metal chelates of N,N-diethyldithiocarbamic acid. A 10-port valve interface was used to couple the LC and GC instruments. Conditions during sample transfer into the GC gave fully concurrent solvent evaporation. The chelates investigated were separated with a short apolar fused silica column. LC preseparation was made with cyano or amino phases using a hexane/dichloromethane mixture as eluent. On-line LC-GC combination seems to be very suitable for the separation of the metal chelates studied.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 13 (1980), S. 396-402 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational barriers and 15N chemical shifts have been measured in a number of ureas and thioureas. As anticipated on the basis of the 15N shifts, several previously unobserved rotational barriers could be detected by using lanthanide reagents or a high field spectrometer. Nearly constant effects on both the rotational activation energy and the 15N shift are produced on going from ureas to the corresponding thioureas, and correlations are found between the ΔG
    Additional Material: 3 Tab.
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  • 10
    ISSN: 0749-503X
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; uracil permease ; transmembrane helices ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The uracil permease gene of Schizosaccharomyces pombe was cloned and sequenced. The deduced protein sequence shares strong similarities with five open reading frames from Saccharomyces cerevisiae, namely the uracil permease encoded by the FUR4 gene, the allantoin permease encoded by DAL4, a putative uridine permease (YBL042C) and two unknown ORFs YOR071c and YLR237w.A topological model retaining ten transmembrane helices, based on predictions and on experimental data established for the uracil permease of S. cerevisiae by Galan and coworkers (1996), is discussed for the four closest proteins of this family of transporters. The sequence of the uracil permease gene of S. pombe has been deposited in the EMBL data bank under Accession Number X98696. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
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