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  • 1
    Electronic Resource
    Electronic Resource
    Preparative fractionation of lignin by gel-permeation chromatography (1969)
    New York : Wiley-Blackwell
    Biopolymers 7 (1969), S. 135-153 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The combination of an agarose gel (Bio-Gel A) and a dioxane-water (1:1) solvent system allowed the fractionation, on a preparative scale, of a very polydisperse, non-derivatized lignin preparation (enzymatically liberated lignin prepared from sweetgum sapwood with Lenzites trabea). Three fractions differing markedly in molecular weight were obtained. A gel of crosslinked alkylated dextran (Sephadex LH-20) with the same solvent system allowed division of the lowest molecular weight fraction into two fractions. These materials were characterized by measurements of intrinsic viscosity and number-average molecular weights in dimethylformamide and dioxane-water. It was established that the two highest molecular weight fractions were associated in an average trimeric form in dioxane-water (1:1) as compared to the form (considered to be molecular) that occurred in dimethylformamide. Molecular size distributions and eluant volumes of the fractions were determined with a Sephadex G-100-formamide system, the latter being one of the most powerful nonaqueous solvents for lignin. Adsorption effects were known to be absent in this case, and the lignin molecules were considered to be unassociated in formamide. The four fractions were distinguishable with the formamide-G-100 system, thus indicating that the original fractionation was based on molecular size. The enzymatically liberated lignin contained molecules that comprised a continuum of molecular weights from approximately monomeric to molecules that were at the limit of the solvating power of dioxane-water (1:1) and dimethylformamide. Limited physicochemical data were consistent with a compact, approximately spherically symmetric shape of the lignin in solution.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1969.360070202
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  • 2
    Electronic Resource
    Electronic Resource
    The graft copolymerization of styrene and lignin. II. Kraft softwood lignin (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1-14 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The radiation-induced graft copolymerization of styrene and various kraft softwood lignins was studied. Expression of the results as the usual “per cent graft” was impossible, because grafting caused the lignin to become extractable in solvents for the styrene homopolymer. However, evaluation of the effects of various solvents on the degree of reaction was made through an indirect, and possibly more characteristic, measure. Grafting was least pronounced under conditions of low lignin accessibility (e.g., when less than 10% methanol was present), but increased with the addition of better lignin solvents or with higher methanol concentrations. The precipitating nature of the latter conditions was also found to contribute to an accelerated rate of grafting. Surprisingly, the graft copolymer was found to degrade at higher doses. Proof of grafting is offered in a fractionation scheme. Measurement of the molecular weight of the polystyrene separated from the lignin backbone allows the estimation of approximately one polystyrene graft per lignin molecule in benzene-extractable copolymers. Two glass transition temperatures could be detected in several fractionated copolymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160101
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  • 3
    Electronic Resource
    Electronic Resource
    Posttranslational modification of ras proteins: Detection of a modification prior to fatty acid acylation and cloning of a gene responsible for the modification (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 261-273 
    Details
    ISSN: 0730-2312
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; subcellular localization ; DPR1 gene ; processing of ras protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Products of ras genes are synthesized as precursors in the cytosol and transported to the plasma membrane by a process which involves posttranslational modification by fatty acid. In this paper, we present evidence for the occurrence in the cytosol of an intermediate modification of ras proteins prior to the fatty acid acylation. The modification is detected by a slight shift in the mobility of the protein on SDS polyacrylamide gel. The fatty acid acylation does not contribute to this mobility shift. This modification is affected by the dpr1 mutation which has recently been shown to affect the processing of yeast RAS proteins. To further characterize the nature of the modification event, we have cloned DPR1 gene from the DNA of Saccharomyces cerevisiae. The gene is actively transcribed in yeast cells producing mRNA of approximately 1.6 kb. Genes related to the DRP1 appear to be present in a distantly related yeast, Schizosaccharomyces pombe as well as in guinea pig and human cells.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360307
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  • 4
    Electronic Resource
    Electronic Resource
    Stability characteristics of deuterated myoglobin (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 2309-2322 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Purified sperm whale myoglobin was deuterated by being exposed to pD 3.5 in D2O buffer for 1 hr, then raised to pD 10.6 for an additional hour, and finally brought to neutrality in a D2O environment. Control myoglobin was similarly treated in H2O. The specific rotation at 233 mμ and/or the absorbance in the Soret region were used to follow the helix-coil transition of myoglobin subjected to denaturation by acid, alkali, urea and guanidine. Deuterated and control myoglobin had similar 50% transition points in the four denaturing media studied (acid: pH 4.4, pD 4.9; alkali: pH 9.4, pD 10.0; urea, 7.2M; guanidine, 2.5M). The shift toward the alkaline side of 0.5 or 0.6 units of the transition induced by either acid or alkaline denaturation reflects only the weakened acidity of ionizable groups in deuterium systems. Deuterated myoglobin in 3.25M guanidine had a 20% faster denaturation rate than that of control. Acid, urea, and guanidine denaturation curves showed fairly steep transitions, taken as indicative of a one-step process involving only two states (native and denatured molecules). Supporting this conclusion was the fact that plots of absorption and polarimetry measurements of the helix-coil transition induced by either acid or guanidine could be superimposed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360101122
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  • 5
    Electronic Resource
    Electronic Resource
    The ultrastructure of the human adrenal medulla: With comparative studies of white ratPartial support by USPHS grant AM-06074, HE 11-114 and NNB 07250. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 169 (1971), S. 173-183 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: There is wide support for the concept that there are two types of secretory cells in adrenal medulla of various species. One cell is filled with electron dense bodies believed to contain norepinephrine; the other cell's lesser stained bodies contain epinephrine. This differential density may be seen by fixation in osmium tetroxide after glutaraldehyde.The two cell types have not been clearly shown in human tissues. Such a failure may be related to fixation. In consideration of this, fresh human adrenal was fixed in cold 1% glutaraldehyde, then 1% osmium tetroxide  -  a procedure known to give satisfactory differentiation in other species. A parallel study with rat tissue was then done.Electron microscopy revealed two types of cells in rats, while in man an obvious cell difference was not found. There is, however, a clear difference in human chromaffin granule density, which implies that the human cells have random numbers of both light and dark granules. The morphologic difference of the cell types in man may be less distinct than in the rat. Another possibility is that in cells with predominantly dark granules, there are co-mingled lighter granules with the coexistence of cells of opposite dominance. Both hormones then would occur in the same cell in varying proportions according to functional demand. It seems highly unlikely that two distinct cell types would have been overlooked with wide sampling, however, in a study of three adrenal glands, one cannot rule out their existence.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091690204
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  • 6
    Electronic Resource
    Electronic Resource
    Maturation and water composition of murine cerebrum, cerebellum, brain stem and spinal cord (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 154 (1966), S. 753-757 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Percentage change in water content and total solids was determined for the developing murine brain for both males and females from birth to 120 days.The central nervous system was divided into four components: (1) cerebrum (2) cerebellum (3) brain stem (4) spinal cord. The percentage of water was determined by dessication for groups of five animals at each day from birth to 20 days and then at five-day increments to day 60 and at day 90 and day 120.Plots of the per cent solids (water content) against body weight showed a linear relationship for all parts except the cerebellum. No sex differences were noted. The cerebellum showed an early rapid water loss with a changing rate to a linear curve as the animal matured.Growth data were submitted to asymptotic regression using a computer to fit a curve y = α+βρx when y is the per cent solid at time × (in days) and α, β, ρ the constants to be determined. All of the central nervous system components gave constants of the same order of magnitude.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091540406
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  • 7
    Electronic Resource
    Electronic Resource
    Solution properties of lignin. Thermodynamic properties and molecular weight determinations (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2381-2396 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Number-average molecular weights and the thermodynamic parameters ΔF̄1, ΔH̄1, and ΔS̄1 have been obtained for lignin in the solvents dimethylsulfoxide, dimethyl-formamide, and dioxane. Widely different molecular weights were found in the different solvents and at the different temperatures as a consequences of molecular association. Analysis of the thermodynamic parameters revealed that these quantities are dominated by the change in solvent structure accompanying the solution process. A correlation between the “goodness” of a lignin solvent and the Hildebrand solubility parameter is consequently misleading in such systems.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111125
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular motion of small molecules in cellulose gels studied by NMR (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 3385-3393 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements of relaxation times, T1 and T2, and self-diffusion coefficients, D, for small molecules, viz., H2O, dioxane and t-butanol, in the gel system cellulose/H2O are reported and compared with those for H2O in a polyacrylamide gel of the same polymer content. The temperature dependence of T1 and D can for all the penetrants be represented by Arrhenius type relations which merely are parallel shifts by the same amount, towards smaller values, of those obtained without polymer. The T2 values for H2O in both gels pass through a shallow minimum over the considered temperature interval (14°-44°C). Furthermore, relaxation times T1 of D2O in the gel system cellulose/D2O are reported; in a plot of ln T1 vs. 1/T, a plateau region is observed at higher temperatures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070261018
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  • 9
    Electronic Resource
    Electronic Resource
    The graft copolymerization of styrene and lignin. I. Hydrochloric acid lignin (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2929-2940 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of methylation of phenolic hydroxyl groups and addition of solvent on the radiation and chemically initiated graft copolymerization of styrene and hydrochloric acid softwood lignin were studied. In the radiation-induced experiments, methylation is found to increase the maximum per cent graft obtainable two or threefold, while methanol addition may increase the value tenfold. Chemically initiated experiments indicate that the main effect of methanol addition is to increase the accessibility of the lignin particles. A mechanism of graft copolymerization of polystyrene and lignin is proposed which requires the reaction to proceed primarily by chain transfer of a polystyrene chain radical to lignin and the subsequent reinitiation of polymerization (i.e., initiation of graft copolymerization) by the lignin radical. The grafting of lignin modifications is then dependent on the type of radical formation (i.e., phenoxy or benzylic) most favored, as well as the usual accessibility considerations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070151203
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  • 10
    Electronic Resource
    Electronic Resource
    The graft copolymerization of styrene and lignin. III. Chain transfer reactions of lignin and lignin model compounds (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 443-451 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of addition of lignin model compounds on the polymerization rate and molecular weight of polymer in the radiation-induced polymerization of styrene was studied. Guaiacol, a model for softwood lignin, reacted slowly with styrene radicals, while 2,6-dimethoxyphenol, a hardwood lignin model, was a much more efficient chain transfer agent. Studies with isoeugenol indicate that allylic or phenoxy radical stability in a conjugated system may terminate polymerization quite effectively. The results are discussed in the light of new and previous data with isolated lignins; they are consistent with the previously presented grafting scheme.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170210
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