Thermal and Barrier Characterizations of Cellulose Esters with Variable Side-Chain Lengths and Their Effect on PHBV and PLA Bioplastic Film Properties

Investigation of the effect of CaCl2 salt on conformations of two anionic poly(amino acids) with different side chain lengths, poly-(α-l glutamic acid) (PGA) and poly-(α-l aspartic acid) (PASA), was performed by atomistic molecular dynamics (MD) simulations. The simulations were performed using both unbiased MD and the Hamiltonian replica exchange (HRE) method. The results show that at low CaCl2 concentration adsorption of Ca2+ ions lead to a significant chain size reduction for both PGA and PASA. With the increase in concentration, the chains sizes partially recover due to electrostatic repulsion between the adsorbed Ca2+ ions. Here, the side chain length becomes important. Due to the longer side chain and its ability to distance the charged groups with adsorbed ions from both each other and the backbone, PGA remains longer in the collapsed state as the CaCl2 concentration is increased. The analysis of the distribution of the mineral ions suggests that both poly(amino acids) should induce the formation of mineral with the same structure of the crystal cell.

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Cellulose-Ester as Membrane Materials for Hemodialysis

The International Journal of Artificial Organs ◽

10.1177/039139889401700704 ◽

1994 ◽

Vol 17 (7) ◽

pp. 385-391 ◽

Cited By ~ 17

Author(s):

M. Diamantoglou ◽

H.D. Lemke ◽

J. Vienken

Keyword(s):

Blood Compatibility ◽

Degree Of Substitution ◽

Cellulose Ester ◽

Regenerated Cellulose ◽

Special Focus ◽

Standard Type ◽

Cellulose Esters ◽

Recent Developments ◽

Cellulosic Membrane ◽

Chain Lengths

The majority of dialysis membranes are fabricated from regenerated unmodified cellulose. This standard type of cellulosic membrane is frequently under attack because of its alleged lack of biocompatibility. Recent developments, however, have proven that a chemical modification of the reactive surface groups of regenerated cellulose, the hydroxylgroups, limits the complement-activating potential of these materials and thus improves its blood-compatibility. We extended the idea of modifying cellulose for improved blood-compatibility to a series of different cellulose esters. Special focus was directed towards the question whether a variation of the type of substituent and degree of substitution could influence the blood-compatibility pattern of these materials: the analysis of blood-compatibility profiles showed a direct dependency on the type of substituent and the degree of substitution (DS). As an example, it was found that the DS, necessary for a complete reduction of complement activation, decreases with increasing chain lengths of aliphatic substituents. Optimal degrees of substitution are characteristic of the type of substituents and enable us to tailor materials specifically for optimized blood compatibility.

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n-Alkylresorcinol Occurrence in Mercurialis perennis L. (Euphorbiaceae)

Zeitschrift für Naturforschung C ◽

10.1515/znc-2010-3-402 ◽

2010 ◽

Vol 65 (3-4) ◽

pp. 174-179 ◽

Cited By ~ 9

Author(s):

Peter Lorenz ◽

Matthias Knödler ◽

Julia Bertrams ◽

Melanie Berger ◽

Ulrich Meyer ◽

...

Keyword(s):

Side Chain ◽

Side Chains ◽

Alkyl Side Chain ◽

Alkyl Side Chains ◽

Chain Lengths ◽

New View

Investigation of the dichloromethane extracts from herbal and root parts of Mercurialis perennis L. afforded a mixture of 11 homologous n-alkylresorcinols (ARs) with saturated odd-numbered alkyl side chains (C15:0-C27:0). In addition to three predominant ARs (C19:0, C21:0 and C23:0), a number of minor ARs were identified by use of LC-MS/MS and GC-MS techniques. Among the compounds detected, four uncommon ARs with evennumbered alkyl side chain lengths were also determined. The overall AR concentration in herbal parts was 7 to 9 times higher compared to that of the roots. The results presented may open a new view on the phytochemistry and pharmacognosy of M. perennis and other members of the Euphorbiaceae family.

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Bioengineering of emulsifier structure: emulsan analogs

Canadian Journal of Microbiology ◽

10.1139/m97-053 ◽

1997 ◽

Vol 43 (4) ◽

pp. 384-390 ◽

Cited By ~ 18

Author(s):

Alexander Gorkovenko ◽

Jinwen Zhang ◽

Richard A. Gross ◽

Alfred L. Allen ◽

David L. Kaplan

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Carbon Source ◽

Chain Length ◽

Acinetobacter Calcoaceticus ◽

Chain Structure ◽

Fatty Acid Esters ◽

Side Chain ◽

Rag 1 ◽

Chain Lengths

Strategies were investigated to modulate the side chain structure of emulsans formed by Acinetobacter calcoaceticus RAG-1. Analysis of emulsan fatty acid side chain groups by gas chromatography – mass spectrometry (GC–MS) revealed that by providing the exogenous n-alkanoic fatty acids 15:0, 16:0, and 17:0, emulsan analogs were formed with 53, 46, and 44 mol%, respectively, of fatty acid substituents with chain lengths equal to that of the carbon source. In contrast, the increase in emulsan fatty acids of chain lengths less than 15 or greater than 17 by providing corresponding shorter and longer chain length fatty acids as carbon sources was not substantial. When [1-13C]-labeled (99% enriched) palmitic acid was used as a carbon source along with acetate, analysis of m/z 75/14 and 87/88 isotopomer ratios by GC-MS indicated that 84 and 86% of the 16:0 and 16:1 (9-cis) side groups, respectively, were incorporated intact from the 16:0 carbon source. The percentage of 14-, 15-, 16-, 17-, and 18-carbon chain length fatty acid esters that were monounsaturated were 11, 26, 50, 70, and 85%, respectively. Based on the observed percentage of unsaturated chain length dependence and almost identical enrichment at C-1 of 16:0 and 16:1 (9-cis) side groups from [1-13C]-labeled experiments, it was concluded that desaturation of preformed n-alkanoic acids was the predominant mechanism of their formation. Further work established correlations between side chain structure and product emulsification specificity/activity, so that bioengineered emulsans with improved selectivity can now be formed.Key words: emulsan, Acinetobacter calcoaceticus RAG-1, fatty acids, direct incorporation, emulsification activity.

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Tubulin Polyglycylation: Differential Posttranslational Modification of Dynamic Cytoplasmic and Stable Axonemal Microtubules inParamecium

Molecular Biology of the Cell ◽

10.1091/mbc.9.9.2655 ◽

1998 ◽

Vol 9 (9) ◽

pp. 2655-2665 ◽

Cited By ~ 46

Author(s):

Marie-Hélène Bré ◽

Virginie Redeker ◽

Joëlle Vinh ◽

Jean Rossier ◽

Nicolette Levilliers

Keyword(s):

Posttranslational Modification ◽

Regulatory Mechanisms ◽

Side Chain ◽

Microtubule Stability ◽

Tubulin Subunit ◽

Tubulin Isoforms ◽

Cellular Extract ◽

Cytoplasmic Microtubules ◽

Chain Lengths

Polyglycylation, a posttranslational modification of tubulin, was discovered in the highly stable axonemal microtubules ofParamecium cilia where it involves the lateral linkage of up to 34 glycine units per tubulin subunit. The observation of this type of posttranslational modification mainly in axonemes raises the question as to its relationship with axonemal organization and with microtubule stability. This led us to investigate the glycylation status of cytoplasmic microtubules that correspond to the dynamic microtubules in Paramecium. Two anti-glycylated tubulin monoclonal antibodies (mAbs), TAP 952 and AXO 49, are shown here to exhibit different affinities toward mono- and polyglycylated synthetic tubulin peptides. Using immunoblotting and mass spectrometry, we show that cytoplasmic tubulin is glycylated. In contrast to the highly glycylated axonemal tubulin, which is recognized by the two mAbs, cytoplasmic tubulin reacts exclusively with TAP 952, and the α- and β- tubulin subunits are modified by only 1–5 and 2–9 glycine units, respectively. Our analyses suggest that most of the cytoplasmic tubulin contains side chain lengths of 1 or 2 glycine units distributed on several glycylation sites. The subcellular partition of distinct polyglycylated tubulin isoforms between cytoplasmic and axonemal compartments implies the existence of regulatory mechanisms for glycylation. By following axonemal tubulin immunoreactivity with anti-glycylated tubulin mAbs upon incubation with aParamecium cellular extract, the presence of a deglycylation enzyme is revealed in the cytoplasm of this organism. These observations establish that polyglycylation is reversible and indicate that, in vivo, an equilibrium between glycylating and deglycylating enzymes might be responsible for the length of the oligoglycine side chains of tubulin.

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