Amino acids combinations with carbohydrates

First attempts to combine pyrolysis with in situ HMDS silylation of organic art materials were reported by Chiavari et al., who were successful in obtaining trimethylsilyl derivatives of fatty acids [52], amino acids [53] and carbohydrates [54]. The same authors also applied pyrolysis-silylation to the analysis of different kinds of natural resins and for each of them diagnostic silylated compounds were identified, even if many were difficult to assign precise structures [55],... 

These proteins are composed of simple proteins in combination with carbohydrates like mucopolysaccharides, which include hyaluronic acid and chondroitin sulphates. On hydrolysis, mucopolysaccharides yield more than 4% of amino-sugars, hexosamine and uronic acid e.g., ovomucoid from egg white. Soluble mucoproteins are neither readily denatured by heat nor easily precipitated by common protein precipitants like trichloroacetic acid or picric acid. The term glycoproteins is restricted to those proteins that contain small amounts of carbohydrate usually less than 4% hexosamine. 

An important biosynthetic pathway leads from amino acids to proteins, alkaloids, and purines, and the latter, in combination with carbohydrates and inorganic phosphate, form the vital nucleic acids. 

Amino acids play an essential role in the physiological processes in our body. They are the main building blocks of the principal structures in our body. Amino acids themselves or in combination with carbohydrates, lipids, etc., form an intricate system of physiologically important structures and functional domains without which life as we know it cannot exist. 

In animals and humans, at intracellular pH, nearly all natural boron exists as boric acid, which behaves as a Lewis acid, and forms molecular additive compounds with amino- and hydroxy acids, carbohydrates, nucleotides, and vitamins through electron donor-acceptor interactions. In most of the commercial dietary boron supplements now available, boron is chelated with amino acids or with hydroxy acids (i.e., glycine, aspartic acid, or citric acid) in combination with vitamins. However, little is known about the molecular structure of these boron chelates. ... 

To date, the most extensively studied polyboron hydride compounds in BNCT research have been the icosahedral mercaptoborane derivatives Na2[B22H22SH] and Na [(B22H22S)2], which have been used in human trials with some, albeit limited, success. New generations of tumor-localizing boronated compounds are being developed. The dose-selectivity problem of BNCT has been approached using boron hydride compounds in combination with a variety of deUvery vehicles including boronated polyclonal and monoclonal antibodies, porphyrins, amino acids, nucleotides, carbohydrates, and hposomes. Boron neutron capture therapy has been the subject of recent reviews (254). 

Some of the potential uses of the fats and oils found in plants have been reviewed and some uses of carbohydrate-based polymers briefly discussed. Plants contain a whole variety of other chemicals including amino acids, terpenes, flavonoids, alkaloids, etc. When the potential for these naturally occurring materials are combined with the secondary products that can be obtained by fermentation or other microbial processes or by traditional chemical transformations, the array of chemicals that can readily be created from renewable resources is huge. In this section a few of the more interesting examples are considered. 

Proteins composed solely of amino acid units are referred to as simple proteins. Many proteins contain other chemical groups in addition to amino acids. These proteins are called conjugated proteins. Proteins containing a carbohydrate unit are called glycoproteins, those with a nucleic acid are called nucleoproteins, and those combined with a lipid are called lipoproteins. High-density lipoproteins (HDLs) and low-density lipoproteins (LDLs) are included in a cholesterol test. LDLs, which... 

The most widely applicable method of optical resolution utilizes a chiral auxiliary, which is taken from either the chiral pool 14 (carbohydrates, terpenes, amino acids etc.) or obtained by previous optical resolution. The auxiliary A, in an optically pure form, combines with the racemic substrate S to form two diastereomers p and n, respectively. 

The oxidative cleavage of an a-oxoacid is a major step in the metabolism of carbohydrates and of amino acids and is also a step in the citric acid cycle. In many bacteria and in eukaryotes the process depends upon both thiamin diphosphate and lipoic acid. The oxoacid anion is cleaved to form C02 and the remaining acyl group is combined with coenzyme A (Eq. 15-33). 

---