Self-Association and Crystallization of Amylose

2007 ◽  
Vol 60 (10) ◽  
pp. 706 ◽  
Author(s):  
Alain Buléon ◽  
Gabrielle Véronèse ◽  
Jean-Luc Putaux
Keyword(s):  
Aqueous Solutions ◽  
Enzymatic Synthesis ◽  
Structural Changes ◽  
The Self ◽  
Model Systems ◽  
Starch Granules ◽  
In Vitro Synthesis ◽  
Self Association ◽  
Lamellar Crystals

Amylose, the linear constituent of starch, consists of α(1,4)-linked glucose monomers. Although weakly involved in the crystalline structure of starch, it can be recrystallized in a variety of allomorphic types, including those encountered in native starch (A- and B-types). Amylose can either be extracted from starch or produced in vitro by enzymatic synthesis using amylosucrase or phosphorylase. Recrystallization and self-association of amylose in aqueous solutions have been widely studied to understand both the crystallization of starch during biosynthesis and the structural changes that occur during starch processing. Depending on the chain length, concentration, and temperature, gels, spherulites, or lamellar crystals can be formed with A or B allomorphic type. Other ligand-dependent allomorphs (the various V-types) are obtained when amylose is complexed with molecules such as alcohols, lipids, or flavours. Amylose also self-associates into networks, spherulites, or axialites during in-vitro enzymatic synthesis by amylosucrase. When a highly branched acceptor like glycogen is used, dendritic nanoparticles are formed by elongation of the external chains. The recrystallization of amylose extracted from starch and the self-association of amylose during its in-vitro synthesis are described. The amylose properties are discussed in terms of polymer behaviour and model systems to investigate the structure and formation of starch granules.

scholarly journals Mapping the self-association domains of ataxin-1: Identification of novel non overlapping motifs

2014 ◽  
Author(s):  
Rajesh Menon ◽  
Daniel Soong ◽  
Cesira de Chiara ◽  
Mark Holt ◽  
John McCormick ◽  
...  
Keyword(s):  
Low Complexity ◽  
The Self ◽  
Spinocerebellar Ataxia Type ◽  
Aggregation Process ◽  
Combined Approach ◽  
Spinocerebellar Ataxia Type 1 ◽  
Polyglutamine Tract ◽  
Self Association

The neurodegenerative spinocerebellar ataxia type 1 (SCA1) is caused by aggregation and misfolding of the ataxin-1 protein. While the pathology correlates with mutations that lead to expansion of a polyglutamine tract in the protein, other regions contribute to the aggregation process as also non-expanded ataxin-1 is intrinsically aggregation-prone and forms nuclear foci in cell. Here, we have used a combined approach based on FRET analysis, confocal microscopy and in vitro techniques to map aggregation-prone regions other than polyglutamine and to establish the importance of dimerization in self-association/foci formation. Identification of aggregation-prone regions other than polyglutamine could greatly help the development of SCA1 treatment more specific than that based on targeting the low complexity polyglutamine region.

scholarly journals Mapping the self-association domains of ataxin-1: Identification of novel non overlapping motifs

2014 ◽  
Author(s):  
Rajesh Menon ◽  
Daniel Soong ◽  
Cesira de Chiara ◽  
Mark Holt ◽  
John McCormick ◽  
...  
Keyword(s):  
Low Complexity ◽  
The Self ◽  
Spinocerebellar Ataxia Type ◽  
Aggregation Process ◽  
Combined Approach ◽  
Spinocerebellar Ataxia Type 1 ◽  
Polyglutamine Tract ◽  
Self Association

The neurodegenerative spinocerebellar ataxia type 1 (SCA1) is caused by aggregation and misfolding of the ataxin-1 protein. While the pathology correlates with mutations that lead to expansion of a polyglutamine tract in the protein, other regions contribute to the aggregation process as also non-expanded ataxin-1 is intrinsically aggregation-prone and forms nuclear foci in cell. Here, we have used a combined approach based on FRET analysis, confocal microscopy and in vitro techniques to map aggregation-prone regions other than polyglutamine and to establish the importance of dimerization in self-association/foci formation. Identification of aggregation-prone regions other than polyglutamine could greatly help the development of SCA1 treatment more specific than that based on targeting the low complexity polyglutamine region.

scholarly journals Mapping and Functional Role of the Self-Association Domain of Vesicular Stomatitis Virus Phosphoprotein

2006 ◽  
Vol 80 (19) ◽  
pp. 9511-9518 ◽  
Author(s):  
Mingzhou Chen ◽  
Tomoaki Ogino ◽  
Amiya K. Banerjee
Keyword(s):  
Amino Acids ◽  
Vesicular Stomatitis Virus ◽  
Critical Role ◽  
The Self ◽  
Dependent Manner ◽  
P Protein ◽  
Vesicular Stomatitis ◽  
Self Association

ABSTRACT The phosphoprotein (P protein) of vesicular stomatitis virus (VSV) is an essential subunit of the viral RNA-dependent RNA polymerase complex and plays a central role in viral transcription and replication. Using both the yeast two-hybrid system and coimmunoprecipitation assays, we confirmed the self-association of the P protein of Indiana serotype (Pind) and heterotypic interaction between Pind and the P protein of New Jersey serotype (Pnj). Furthermore, by using various truncation and deletion mutants of Pind, the self-association domain of the Pind protein was mapped to amino acids 161 to 210 within the hinge region. The self-association domain of Pind protein is not required for its binding to nucleocapsid and large proteins. We further demonstrated that the self-association domain of Pind protein is essential for VSV transcription in a minireplicon system and that a synthetic peptide spanning amino acids 191 to 210 in the self-association domain of Pind protein strongly inhibited the transcription of the VSV genome in vitro in a dose-dependent manner. These results indicated that the self-association domain of Pind protein plays a critical role in VSV transcription.

Cambios microestructurales del almidón de Canavalia ensiformis modificado por métodos térmicos / Microstructural changes of Canavalia ensiformis starch modified by thermal methods

1999 ◽  
Vol 5 (1) ◽  
pp. 31-40 ◽  
Author(s):  
A.M. Rincón Carlés ◽  
E.E. Pérez Sira ◽  
Z.M. González Parada ◽  
P.J. Rodríguez González
Keyword(s):  
Functional Properties ◽  
Structural Changes ◽  
Model Systems ◽  
Water Model ◽  
Extrusion Cooking ◽  
Starch Granules ◽  
Thermal Methods ◽  
Canavalia Ensiformis ◽  
Dry Heat ◽  
Excess Water

The aim of this study was to evaluate the structural changes of Canavalia ensiformis starch, which was gelatinized in limited and excess water model systems and modified by dry heat, extrusion-cooking and pregelatinization, as well as to relate the changes caused by extrusion cooking and pregelatinization with some functional properties of this starch. The microscopical observation performed in the model systems showed granular swelling, solubility and lixiviation of intragranular material, while dry heat did not affect the starch microstructure. The extrusion-cooking partially changed the starch mor phology, with some granules affected, while others remained intact; the pregelatinization totally al tered the granular structure and the starch granules showed a coarse and flaky appearance. These changes could be associated with the functional properties of canavalia starch, although the most evident variations were produced by the pregelatinization process.

scholarly journals In vitro ectomycorrhiza formation by monokaryotic and dikaryotic isolates of Pisolithus microcarpus in Eucalyptus grandis

2010 ◽  
Vol 34 (3) ◽  
pp. 377-387 ◽  
Author(s):  
Maurício Dutra Costa ◽  
André Narvaes da Rocha Campos ◽  
Matheus Loureiro Santos ◽  
Arnaldo Chaer Borges
Keyword(s):  
Lateral Root ◽  
Morphological Changes ◽  
Lateral Roots ◽  
Eucalyptus Grandis ◽  
Model Systems ◽  
Root Yield ◽  
Root Tips ◽  
In Vitro Synthesis ◽  
Synthesis Medium

The formation of ectomycorrhizas by monokaryotic and dikaryotic isolates of Pisolithus microcarpus (Cooke & Massee) G. Cunn. in Eucalyptus grandis W. Hill ex Maid. was studied by in vitro synthesis in Petri dishes. The formation of ectomycorrhizas was observed for all strains tested. Ectomycorrhizas formed by the monokaryotic strains presented a sheath of hyphae around the roots and a Hartig net limited to the epidermis layer, typical of the angiosperm ectomycorrhizas. Colonization rates, a measure of the number of ectomycorrhizas in relation to the total number of lateral root tips, varied from 23 to 62%. Some monokaryotic strains stimulated the formation of lateral roots, promoting increases of up to 109% above the control. The presence of some of the isolates in the in vitro synthesis medium stimulated the production of thicker lateral root tips. The dimensions of the lateral roots tips and ectomycorrhizas varied from one isolate to the next, indicating a variation in their capacity to provoke morphological changes in the host plant roots. The dikaryotic strain M5M11 presented higher values for lateral root yield, number of ectomycorrhizas, and colonization percentage than the corresponding monokaryotic strains, M5 and M11. This indicated the possibility of selecting compatible performing monokaryotic isolates for the yield of superior dikaryotic strains. The set of monokaryotic strains tested varied greatly in their ability to colonize E. grandis roots and cause secondary metabolism-related morphological changes in roots, providing a wealth of model systems for the study of genetic, physiological, and morphogenetic processes involved in Pisolithus-Eucalyptus ectomycorrhiza formation.

Influence of the self-association of oleandomycin on its extraction from aqueous solutions

1984 ◽  
Vol 18 (9) ◽  
pp. 643-648
Author(s):  
E. V. Komarov ◽  
L. G. Kardo-Sysoeva ◽  
V. P. Mikhailova
Keyword(s):  
Aqueous Solutions ◽  
The Self ◽  
Self Association
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