Amino acids water solubility

A good example of this class is the principle active component in bee venom, melittin. Melittin is a 26 amino acid water-soluble peptide with a highly cationic... 

Amino acids. Because of their zwitterionic nature, amino acids are soluble in water. Their solubility in organic solvents rises as the fat-soluble portion of the molecule increases. The likeliest impurities are traces of salts, heavy metal ions, proteins and other amino acids. Purification of these is usually easy, by recrystallisation from water or ethanol/water mixtures. The amino acid is dissolved in the boiling solvent, decolorised if necessary by boiling with Ig of acid-washed charcoal/lOOg amino acid, then filtered hot, chilled, and stood for several hours to crystallise. The crystals are filtered off, washed with ethanol, then ether, and dried. 

The structure-taste relationships will be discussed in detail. Dipeptide esters are closely related to amino acids in chemical structure and properties. Hence, we selected amino acids as the standard to which sweet peptides were related. The structural features of sweet-tasting amino acids have been best explained by Kaneko (12) as shown in Figure 2, in which an amino acid will taste sweet when R2 is H, CH3 or C2H5, whereas the size of Ri is not restricted if the amino acid is soluble in water. 

Amliruethaire sulfooxic acid, see Taurine Amino groups, water solubility, 29 Aminolevulinic acid dehydratase, 753, 75S Atninolevulittic acid synthetase, 543, 753 Aminopeptidase N, 88-89 Aminolransf erases, 209,425-428 Ammonia... 

The purification and separation first requires removal of the enzyme. This is, of course, soluble ir. the aqueous buffer solution at pH 8, but acidification and heating denatures the protein (rather like heating egg white) and destroys its structure. The solid material filtered off is the denatured enzyme The separation in ethanol works because the very polar amino acid is soluble only in water but the more organic amide is soluble in ethanol. The amide has an extra organic group and only one ver polar group (CO2H). In addition, it does not form a zwitterion. 

The amino acids thus have the unusual ability to form dipolar ions, denoted by the + sign on the amino group and the—sign on the COO. This property makes amino acids highly soluble in polar solvents like water or ethanol, each polar end attracted to the suitable solvent (see Box 4.14). 

Because of the ionic charge, separation of amino acids from inorganic salts may be difficult (Scott, 1969) and requires considerable sample cleanup as described in Chapter 4. Amino acids are soluble in water, but some are less soluble than... 

Samples of the club moss L. complamtum collected in Hokkaido were extracted with MeOH, and the MeOH extract was partitioned between EtOAc and 3% tartaric acid. Water-soluble materials, adjusted to pH 10 with sat. Na2C03, were partitioned with CHCI3. CHCls-soluble materials were subjected to an amino silica gel column, in which a fraction eluted with CHCl3/MeOH (1 1) was purified by a silica gel column to afford complanadine A (43, 0.003% yield) (56), together with the known, related alkaloid, lycodine (84, 0.0005%) 58). 

The amino-acids are colourless, crystalline substances which melt with decomposition. They are mostly soluble in water and insoluble in alcohol. 

H2N (CH2]5 NH2. a syrupy fuming liquid, b.p. 178-180 - C. Soluble in water and alcohol. Cadaverine is one of the ptomaines and is found, associated with pulrescine, in putrefying tissues, being formed by bacterial action from the amino-acid lysine. It is found in the urine in some cases of the congenital disease cystinuria. The free base is poisonous, but its salts are not. 

C4H6N2O2. Sublimes 260"C sparingly soluble in water hydrolysed by alkalis or mineral acids to glycylglycine. It and substituted dike-topiperazines are formed by the condensation of amino-acids, and are obtained in small quantities on the hydrolysis of proteins. 

H2N-CH2 [CH2j3.CH(NH2) COOH. Colourless needles, m.p. 224 C (decomp.), very soluble in water, insoluble in alcohol. L-(-H)-Lysine is one of the basic amino-acids occurring in particularly large quantities in the protamine and histone classes of proteins. It is an essential amino-acid, which cannot be synthesized by the body and must be present in the food for proper growth. It can be manufactured by various fermentation processes or by synthesis. 

M.p. 283 C (decomp.). Soluble in water and alcohol. The naturally occurring substance is laevorotatory. Methionine is one of the natural sulphur-containing amino-acids, and is present in small quantities in the hydrolysis pro-... 

Water-soluble globular proteins usually have an interior composed almost entirely of non polar, hydrophobic amino acids such as phenylalanine, tryptophan, valine and leucine witl polar and charged amino acids such as lysine and arginine located on the surface of thi molecule. This packing of hydrophobic residues is a consequence of the hydrophobic effeci which is the most important factor that contributes to protein stability. The molecula basis for the hydrophobic effect continues to be the subject of some debate but is general considered to be entropic in origin. Moreover, it is the entropy change of the solvent that i... 

These three amino-acids are colourless and readily soluble in water ... 

An amino-acid, although insoluble in water (e.g., anthranilic acid), is usually soluble in excess of mineral acid in such a case it is important to make the solution only very slightly acid. This applies also to a mixture of a neutral and a basic substance, from which dil. HCl will extract an amino-acid the solution must then be carefully treated with NaOH to precipitate the amino-acid. 

The physical properties of a typical amino acid such as glycine suggest that it is a very polar substance much more polar than would be expected on the basis of its formula tion as H2NCH2CO2H Glycine is a crystalline solid it does not melt but on being heated It eventually decomposes at 233°C It is very soluble m water but practically insoluble m nonpolar organic solvents These properties are attributed to the fact that the stable form of glycine is a zwittenon, or inner salt... 

Famotidine. Also known as Pepcid, famotidine [76824-35-6] (AT-(aminosulfonyl)-3-([[2-[(diaminomethylene) amino]-4-thia2olyl] methyl]thio)propariimidamide (2) is a white to pale yellow crystalline compound, freely soluble in glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in ethanol. It may be prepared by the method described in Reference 3. 

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