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Journal ArticleDOI

The relationship between methoxyl content and gelling temperature of agarose

01 May 1970-Carbohydrate Research (Elsevier)-Vol. 13, Iss: 2, pp 247-256
TL;DR: In this article, the gelling temperature of 1.5% agarose sols was found to increase with increasing methoxyl content of the agaroses, and only 3 failed to follow this pattern.
About: This article is published in Carbohydrate Research.The article was published on 1970-05-01. It has received 173 citations till now. The article focuses on the topics: Agarose.
Citations
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Journal ArticleDOI
B. G. Johansson1
TL;DR: A simple technique for agarose gel electrophoresis allowing the simultaneous separation of 15 samples in less than one hour is described, which could serve as a valuable analytical tool in protein chemistry.
Abstract: A simple technique for agarose gel electrophoresis allowing the simultaneous separation of 15 samples in less than one hour is described. The method is very suitable for clinical routine analyses o...

922 citations

Journal ArticleDOI
TL;DR: A double helix model is proposed that accounts for the sign and magnitude of the optical rotation shift that accompanies the sol-gel transitions and is sterically accessible to each of the various substituted forms.

671 citations

Book ChapterDOI
TL;DR: These interactions are important in many of the industrial applications of galactomannans, and a study of them may also help provide an understanding of the associations among polysaccharide chains, contributing to biological cohesion and texture.
Abstract: Publisher Summary This chapter discusses the interaction of galactomannans with other polysaccharides. The general chemistry of the galactomannans has been reviewed by Whistler and Smart and others. The chapter discusses the uses of guar and locust-bean gums in various industrial applications and investigates the structural chemistry of galactomannans, especially as revealed by enzymic studies. Mixtures of locust-bean gum with the non-gelling polysaccharide from Xanthomonas campestris have been shown to interact synergistically to give firm, rubbery gels, whereas the use of the galactomannan from C yamopsis tetragonolobus (guar gum) results only in viscosity enhancement. These interactions are important in many of the industrial applications of galactomannans, and a study of them may also help provide an understanding of the associations among polysaccharide chains, contributing to biological cohesion and texture. The two main groups of galactomannan polysaccharides are those derived from (1) the endosperm of plant seeds, the vast majority of which originate in the Leguminoseae, and (2) microbial sources, in particular, the yeasts and other fungi. D-Mannose and D galactose are also found in numerous other plant polysaccharides—for example, glucomannansm, mannans, and galactans.

614 citations

Journal ArticleDOI
TL;DR: The term ‘agaroids’ is applied to Gracilaria agars produced without alkaline hydrolysis of sulphates, with greater sulphate content and much less gel strength, which does not show the synergistic reaction with locust bean gum apparent with Gelidium agar.
Abstract: The world's first source of agar, from the middle of the seventeenth century, was Gelidium from Japan, but by the beginning of the twentieth century demand for the phycocolloid exceeded of the supply of this alga. Since then Gracilaria has played an important role in the production of agar. Currently agars are obtained from five genera in three orders of red algae and marketed as ‘natural agar’ in squares or strips or as ‘industrial agar’ in powder form. The development of production processes through alkaline hydrolysis of sulphates has allowed a good quality food agar to be obtained from Gracilaria. This does not show the synergistic reaction with locust bean gum apparent with Gelidium agar. The term ‘agaroids’ is applied to Gracilaria agars produced without alkaline hydrolysis of sulphates, with greater sulphate content and much less gel strength. Unlike Gelidium, Gracilaria has to be processed in a short period of time and cannot be allowed to remain in storage for use during years of lower availability. Statistics of imports of agarophytes to Japan during the last 10 years give an indication of the state of the market. During this period there was a marked reduction in Gracilaria imports, mainly from Chile, but also the Philippines, Indonesia and South Africa, mainly due to the overall increase in the capacity of agar production in Gracilaria-producing countries.

261 citations

Book ChapterDOI
TL;DR: This chapter is devoted to a description of the structural diversity of polysaccharides found in the red algae, with special emphasis on the methods of structural analysis of sulfated galactans.
Abstract: Red algae (Rhodophyta) are known as the source of unique sulfated galactans, such as agar, agarose, and carrageenans. The wide practical uses of these polysaccharides are based on their ability to form strong gels in aqueous solutions. Gelling polysaccharides usually have molecules built up of repeating disaccharide units with a regular distribution of sulfate groups, but most of the red algal species contain more complex galactans devoid of gelling ability because of various deviations from the regular structure. Moreover, several red algae may contain sulfated mannans or neutral xylans instead of sulfated galactans as the main structural polysaccharides. This chapter is devoted to a description of the structural diversity of polysaccharides found in the red algae, with special emphasis on the methods of structural analysis of sulfated galactans. In addition to the structural information, some data on the possible use of red algal polysaccharides as biologically active polymers or as taxonomic markers are briefly discussed.

232 citations

References
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Journal ArticleDOI
09 Sep 1950-Nature
TL;DR: Modifications are introduced, based on a test given by Feigl for reducing sugars, which eliminate the heating step, and in which the reagents are applied in organic solvents, thus removing the danger of migration of the sugar spots.
Abstract: THE ammoniacal silver nitrate spray1 used for the detection of sugars has several disadvantages; to those mentioned by Partridge2 should be added the necessity for very careful control of the heating step, particularly important in laboratories lacking special apparatus. We have introduced modifications, based on a test given by Feigl3 for reducing sugars, which eliminate the heating step, and in which the reagents are applied in organic solvents, thus removing the danger of migration of the sugar spots. The method has been in use for more than a year, and has proved easy to handle and extremely reliable.

3,526 citations

Journal ArticleDOI
TL;DR: A new method for preparation of agarose, the neutral polysaccharide of Agar, for gel electrophoresis, gel diffusion, and chromatography is described, based on the fact that cetylpyridinium chloride has the property of precipitating acidicpolysaccharides but not neutral.

118 citations

Journal ArticleDOI
TL;DR: Although relatively simple, the method ensures a product essentially free from sulphate and possessing a minimum of electroendosmotic and ion-exchange properties, applications to tissue culture and physico-chemical methods are described.

63 citations

Journal ArticleDOI
TL;DR: Commercial agar was subjected to complete hydrolysis with dilute sulfuric acid, and the products were carefully investigated, finding 4-O-methyl-L-galactose is a new compound, so its structure has been fully investigated.
Abstract: Commercial agar was subjected to complete hydrolysis with dilute sulfuric acid, and the products were carefully investigated. Besides D- and L-galactose, which have been known to exist, there were isolated small amounts of D-xylose, 6-O-methyl-D-galactose, 4-O-methyl-L-galactose, and O-methylpentose, all the sugars except the last one being obtained in crystalline forms. Among these products, 4-O-methyl-L-galactose is a new compound, so its structure has been fully investigated. As commercial agar is made from Gelidium amansii, occasionally mixed with several other species of seaweeds, the experiments were repeated for the agar prepared from G. amansii only. The same products as those from commercial agar were isolated except the O-methylpentose.

39 citations