Search results for "Macro"

Macromolecules with groups of high reactivity

1960

Reactions on the reactive groups of macromolecular substances (e.g., cellulose) have long been known, even since before the structures of macromolecules were understood. H. Staudinger carried out numerous reactions with macromolecules, maintaining the degree of polymerization constant, in order to substantiate the macromolecular structure of the substances investigated (polymeric-analogous reactions). During the last fifteen years reactions with macromolecules have been investigated because it was desirable to compare the chemical diversity of low molecular weight compounds with the corresponding chemical diversity of macromolecular compounds. These endeavors bring forth materials which sup…

Light Regulation of the Thylakoid LHCII Protein Phosphorylation at the Substrate Level

1998

The distribution of light energy between the two photosystems as well as the light-induced turnover of PSII proteins are regulated by the reversible phosphorylation of LHCII and the PSII-core proteins. The thylakoid protein kinase(s) is activated by a signal transduction system involving the interaction of reduced plastoquinone with the quinol oxidation site of the cytochrome bf complex [1]. Phosphorylation of the mobile pool of LHCII induces dissociation of this antenna from PSII and allows its interaction with the PSI in the stroma exposed membranes (state transition)[21. Dephosphorylation of LHCII by a membrane -bound phosphatase appears to be regulated by a cyclophilinlike protein locat…

Hydrodynamic chromatography of macromolecules on 2 μm non-porous spherical silica gel packings

1989

Non-porous spherical 2μm silica gel particles have been tested as packing for hydrodynamic chromatography of macromolecules (HDC). Columns packed with these particles in 250×4.6mm i.d. columns can be operated very efficiently (e.g. a reduced plate height of about 2) when the detection cell is miniaturized. The packing is suitable for the separation of polystyrenes of Mw of 104–107 by hydrodynamic chromatography and the retention behaviour of polystyrenes agrees well with the known theoretical models. Preliminary results on the applicability of HDC for the separation of biopolymers are presented.

1993

A macromonomer was prepared from succinimido methacrylate and poly(N-isopropylacrylamide) (PIPA) with an amino end group. The macronomer (MA-PIPA) obtained shows a temperature-responsive transition phenomenon from coil to globule in water at about 36°C. For the copolymer of MA-PIPA with acrylamide (ratio of monomer residues of N-isopropylacrylamide (IPA) and acrylamide (AAm) 10:3), the transition temperature of the PIPA chain was the same as that of the macromonomer, whereas the transition temperature of a linear copolymer of IPA and AAm (ratio of the monomer residues 10:3) was much higher than that of PIPA (52°C). Microspheres were prepared by emulsion polymerization of the macromonomer an…

Biosensors Applied to Quantification of Ethanol in Beverages

2019

Abstract The quality control in the processing of alcoholic beverages is major concern for producers and regulatory agencies, particularly for ethanol content which is mandatory in the label of alcoholic beverages in many countries. The use of biosensors can be of great interest in this context that usually requires laborious and costly protocols. Biosensors are composed by two principal components: the biological recognition element and the transducer. Particularly for ethanol evaluation, the use of alcohol dehydrogenase (ADH) or oxidase (AOX) is commonly reported in the literature which allowed the production of optical and electrochemical biosensors. These biosensors can aid in the deter…

Monomeric vs. polymeric bonded iminodiacetate silica supports in high-performance ligand-exchange chromatography

1983

The synthesis of monomeric and polymeric bonded iminodiacetate-groups on silica supports is described. The polymeric support offers advantages over the monomeric, such as (i) preparation is much simpler, (ii) higher surface concentration of functional groups can be achieved without loss of efficiency and (iii) hydrolytic stability. Cu2+ loaded supports were examined for their kinetic performance, in particular for the C-parameter of the Knox equation, and for their hydrolytic stability. Calculation of the surface coverage shows that only a rather thin polymeric layer is formed; this is in agreement with the results of the kinetic performance. The retention of α-amino acids on the Cu2+ loade…

Preparation and Recycling of Plasticized PLA

2010

Poly(lacticacid)(PLA)hasbeengainingarisinginterestoverthe last years as a biodegradable and environmental-friendly substitute of traditional non-biodegradable poly-mers.Several ways exist to synthesize PLA, however, poly-merization through lactide formation is the most used onindustrial scale, allowing to obtain optimum results interms of mechanical and thermal properties.

N-trifluoracetyl-nylon 66 als polymeres reagenz

1979

N-Trifluoroacetyl-Nylon 66 (2) obtained by the reaction of Nylon 66 (1) with trifluoroacetic anhydride is very suitable as a polymeric reagent for the trifluoroacetylation of amines and alcohols. The advantages of 2 compared with low molecular trifluoroacetylating reagents are discussed. The selectivity against different substituted anilines and against structurally isomeric secondary amines was studied intensively by kinetic measurements.

Über die kinetik und den mechanismus der biosynthese der cellulose in den höheren pflanzen (nach versuchen an den samenhaaren der baumwolle)

1966

Abstract The quantity of cellulose synthesized on growing cotton bolls and the corresponding degree of polymerisation have been measured as a function of time. It was found that the biosynthesis proceeds in two distinct stages, beginning with a slow process yielding the “primary” cellulose with a non-uniform degree of polymerisation of about 2000–6000 followed by a more rapid process yielding a large amount of “secondary cellulose” with a high and uniform degree of polymerisation of about 14000 (mol. wt. 2.3·106). During the second stage the degree of polymerisation is independent of time. It is shown that the two kinds of cellulose correspond to the primary and secondary cell wall. In orde…

Spectroscopic study of polynucleotides in cationic W/O microemulsions

2007

Water has an active and key role in determining the structure of DNA. Entrapment of DNA and of synthetic model polynucleotides in reverse micelles, where the water activity can easily be modulated, may be a useful way of assessing the influence of water on DNA characteristics; it may also offer useful ideas on the problem of how the giant DNA molecule can be confined in the limited space of cell nuclei. The quaternary microemulsion CTAB n-hexane|n-pentanol| water was used to entrap calf thymus DNA, and the model polynucleotides single-strand polyA, single-strand polyT and duplex polyAT. Ultraviolet spectros-copy, specifically the band at 260 nm, was used to compare the pairing of complement…