Biological interactions between polysaccharides and divalent cations: The egg‐box model
TL;DR: It is shown that spedfic binding of divalent cations to a polysaechafide polyelectro]ym, leading firm cohesion between the chains, can cause characteristic effects in the c~rcutar diehroism spectrum which are understandabb in terms of modem theo~, [ l ].
About: This article is published in FEBS Letters.The article was published on 1973-05-15. It has received 2505 citations till now.
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TL;DR: This review will provide a comprehensive overview of general properties of alginate and its hydrogels, their biomedical applications, and suggest new perspectives for future studies with these polymers.
5,372 citations
TL;DR: The view of critical questions regarding pectin structure, biosynthesis, and function that need to be addressed in the coming decade are presented and new methods that may be useful to study localized pectins in the plant cell wall are described.
1,795 citations
TL;DR: The structure, chemistry of gelation, interactions, and industrial applications soft pectin are described.
Abstract: Pectin is an important polysaccharide with applications in foods, Pharmaceuticals, and a number of other industries. Its importance in the food sector lies in its ability to form gel in the presence of Ca2+ ions or a solute at low pH. Although the exact mechanism of gel formation is not clear, significant progress has been made in this direction. Depending on the pectin, coordinate bonding with Ca2+ ions or hydrogen bonding and hydrophobic interactions are involved in gel formation. In low‐methoxyl pectin, gelation results from ionic linkage via calcium bridges between two carboxyl groups belonging to two different chains in close contact with each other. In high‐methoxyl pectin, the cross‐linking of pectin molecules involves a combination of hydrogen bonds and hydrophobic interactions between the molecules. A number of factors—pH, presence of other solutes, molecular size, degree of methoxylation, number and arrangement of side chains, and charge density on the molecule— influence the gelation o...
1,314 citations
Cites background from "Biological interactions between pol..."
...The egg box structure has been suggested to provide stability to the middle lamella in the plant cell wall.(14)-(113) The size of the egg box junction zones is limited by the presence of sequences containing mannuronate residues, which interrupt the polyguluronate blocks....
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TL;DR: The identification of glycosyltransferases involved in pectin synthesis is essential to the study of cell wall function in plant growth and development and for maximizing the value and use of plant polysaccharides in industry and human health.
1,309 citations
TL;DR: The structural and mechanical properties of gels formed from biopolymers are discussed in this paper, both in terms of the techniques used to characterise these systems, and in the systems themselves.
Abstract: The structural and mechanical properties of gels formed from biopolymers are discussed both in terms of the techniques used to characterise these systems, and in terms of the systems themselves The techniques included are spectroscopic, chiroptical and scattering methods, optical and electron microscopy, thermodynamic and kinetic methods and rheological characterisation The systems considered are presented in order of increasing complexity of secondary, tertiary and quaternary structure, starting with gels which arise from essentially ‘disordered’ biopolymers via formation of ‘quasicrystalline’ junction zones (eg gelatin, carrageenans, agarose, alginates etc), and extending to networks derived from globular and rod-like species (fibrin, globular proteins, caseins, myosin) by a variety of crosslinking mechanisms Throughout the text, efforts are made to pursue the link (both from experiment and from theory) between the structural methods and mechanical measurements As far as we are aware this is the first major Review of this area since that of J D Ferry in 1948 — The interest shown by polymer physicists in more complex biochemical systems, and the multi-disciplinary approaches now being applied in this area, make the format adopted here, in our opinion, the most logical and appropriate
1,231 citations
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TL;DR: The gel state is considered characteristic of polysaccharides in the way that polypeptides and globular proteins can characteristically occur as compact particles having a high degree of internal order, or nucleic acids can occur as chain pairs in highly ordered and complementary association.
Abstract: Publisher Summary It is noted that the gel is the most typical state for polysaccharides, both in biological and artificial systems. The polymer chains usually form an interconnected network that gives rise to characteristic texture and properties. Polysaccharide gels have various biological functions essentially in the wall of the young plant-cell, in animal fluids and connective tissues, and in the bacterial capsule. They also have widespread commercial uses, particularly in foodstuffs, cosmetics, paper, and textiles. The gel state is considered characteristic of polysaccharides in the way that polypeptides and globular proteins can characteristically occur as compact particles having a high degree of internal order, or nucleic acids can occur as chain pairs in highly ordered and complementary association. Polysaccharides also make a distinctive contribution to natural-polymer chemistry in showing, in terms of molecular structure, interaction of chain molecules in three-dimensions to provide physical and biological properties of gels.
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TL;DR: The uronic acid sequence of several alginate samples has been determined by splitting the alginates into alternating and homopolymeric fractions by partial acid hydrolysis, and determining the relative proportions of mannuronic acid blocks and guluronic Acid blocks in the homopolymer fraction by p.r.m. spectroscopy.
222 citations