Solubilities and Chromatographic Behavior

Solubility and chromatographic behavior of PC-1 were very similar to those reported for SG-1 (scarltoxin) from parrotfish (14), scaritoxln from the turban shell (38), and PL toxin II (scarltoxin-llke toxin) from lima (23). The possibility of PC-1 being a derivative of okadaic acid should not be overlooked. 

Melting and Boiling Points, Solubility, and Chromatographic Behavior... 

Based on the solubility and chromatographic behavior of plasteins, Hofsten and Lalasidis (15) concluded that gel formation was due to nonpolar interactions of small hydrophobic peptides. 

Certain classes of lipids are susceptible to degradation under specific conditions. For example, all ester-linked fatty acids in triacylglycerols, phospholipids, and sterol esters are released by mild acid or alkaline treatment, and somewhat harsher hydrolysis conditions release amide-bound fatty acids from sphingolipids. Enzymes that specifically hydrolyze certain lipids are also useful in the determination of lipid structure. Phospholipases A, C, and D (Fig. 10-15) each split particular bonds in phospholipids and yield products with characteristic solubilities and chromatographic behaviors. Phospholipase C, for example, releases a water-soluble phosphoryl alcohol (such as phosphocholine from phosphatidylcholine) and a chloroform-soluble diacylglycerol, each of which can be characterized separately to determine the structure of the intact phospholipid. The combination of specific hydrolysis with characterization of the products by thin-layer, gas-liquid, or high-performance liquid chromatography often allows determination of a lipid structure. 

Boiling points and melting points are considered from the point of view of intermolecular forces between the molecules, together with solubilities and chromatographic behavior, both gas and liquid chromatography. The topic of aromaticity and stability in general is covered as befits its importance. Conformations, particularly of the cyclic non-planar compounds, are dealt with. A section on tautomerism covers both prototropic tautomerism (annular and of substituents) and ring-chain tautomerism. 

New sections describing physical data, solubilities, and chromatographic behavior have been incorporated into this edition. 

Comprehensive coverage of thermodynamic aspects for the 1,4-diazocines was presented in CHEC-II(1996) and included discussion on physical properties, such as melting points, solubility, and chromatographic behavior,... 

Properties of proteins such as solubility and chromatographic behavior depend on the residues that are accessible to the solvent. The nonpolar residues buried in the interior of the molecules should not directly affect these properties. Therefore, the surface hydrophobicity may be the more relevant parameter. Of course, the ideal model depicted by the polarity ratio is never attained. Because of the steric constraints and the inevitable adjacency of polar and nonpolar residues in the amino acid sequence, a proportion of nonpolar residues will be found at or close to the periphery of molecules. For proteins whose structures have been determined (e.g., by x-ray crystallography), it is possible to calculate the surface hydrophobicity. Some values are recorded in Table 9.1. Because of their heterogeneity, cereal proteins are not easily amenable to structure determination, so their surface hydrophobicities have not been calculated. 

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