Polyhydroxy compounds hydrates

The effect of polyhydroxy compounds has been explained on the basis of the formation of 1 1 and 1 2-mole ratio complexes between the hydrated borate ion and 1,2- or 1,3-diols ... 

Uedaira Hi, Uedaira Ha. 2001. Role of hydration of polyhydroxy compounds in biological systems. Cell Mol Biol 47 823-829. 

The addition of polyhydroxyl compounds to enzyme solutions have been shown to increase the stabilities of enzymes, (13,16,19,20). This is thought to be due to the interaction of the polyhydroxyl compound, (e.g. sucrose, polyethylene glycols, sugar alcohols, etc), with water in the system. This effectively reduces the protein - water interactions as the polyhydroxy compounds become preferentially hydrated and thus die hydrophobic interactions of the protein structure are effectively strengthened. This leads to an increased resistance to thermal denaturadon of the protein structure, and in the case of enzymes, an increase in the stability of the enzyme, shown by retention of enzymic activity at temperatures at which unmodified aqueous enzyme solutions are deactivated. 

The chief perplexities encountered in the identification and determination of the structure of a C-glycosyl compound are those to be expected in the handling of polyhydroxy compounds, namely, difficulties in purifying the starting material and uncertainties in the determination of the degree of hydration and the number of hydroxyl groups. For the latter, complete methylation and subsequent methoxyl determination seems to provide the most reliable method. 

Polyhydroxy surfactants have recently received some attention as alternatives to EO materials. Polyhydroxy compounds are more strongly hydrated than EO groups hence the mesophases exist to high temperatures. Also, the intermolecular H-bonding... 

Carbohydrates are the most abundant of all organic compounds in the biosphere. Many members of the carbohydrate class have the empirical formula Cx(H20)y, and are literally hydrates of carbon. The fundamental units of the carbohydrate class, the monosaccharides, are polyhydroxy aldehydes or ketones and certain of their derivatives. As with other classes of biologically important compounds, much of the function of the carbohydrates derives from the ability of the monosaccharides to combine, with loss of water, to form polymers oligosaccharides and polysaccharides. The chemistry of carbohydrates is, at its core, the chemistry of carbonyl and hydroxyl functional groups, but these functional groups, when found in the same compound, sometimes exhibit atypical properties. The discussion that follows is designed to review the aspects of carbohydrate chemistry that are especially important for isolation, analysis, and structure determination of biologically important carbohydrates. 

Historically, carbohydrates were thought to be hydrates of carbon on the basis of their molecular formulas Cn(H20)m- More realistically, carbohydrates are now considered polyhydroxy aldehydes, polyhydroxy ketones, or substances that yield such compounds on acid hydrolysis. 

Early chemists noted that carbohydrates have molecular formulas that make them appear to be hydrates of carbon, C (H20) —whence the name. Eater structural studies revealed that these compounds were not hydrates because they did not contain intact water molecules, but the term carbohydrate persists. Carbohydrates are polyhydroxy aldehydes such as o-glucose, polyhydroxy ketones such as o-fmctose, and compounds such as sucrose that can be hydrolyzed to polyhydroxy aldehydes or... 

Chemically, carbohydrates are polyhydroxy aldehydes or polyhydro ketones or substances that yield these compounds when hydrolyzed. The name carbohydrate was given to this class of compounds many years ago by French scientists who called them hydrates de carbone because their empirical formulas approximated (C H20) . However, the hydrogen and oxygen do not actually exist as water or in hydrate form, as we have seen in such compounds as BaClj 2 HjO. Empirical formulas used to represent carbohydrates are Cj,(H20)y and (CH20) . 

---