Chemical Reactions of Amino Acids

The reactions of amino acids with ninhydrin, carbon dioxide, metal ions, and glucose are described below. The last three are of physiological importance. 

Reaction of an a-amino acid with ninhydrin, Two molecules of ninhydrin and the nitrogen atom of the amino acid are involved in the production of the purple product. 

Ammonia, some amines, and some proteins and peptides will also yield a colored product but will not generate CO2. Thus, the colorimetric analysis is not specific for amino acids unless CO2 release is measured or the amino acids are purified and freed from interfering materials (the usual procedure). The color reaction with ninhydrin is used extensively in manual and automated procedures. 

CO2 adds reversibly to the un-ionized amino group of an amino acid. The product is a carbamate (or carboxyamino) derivative. 

This type of reaction accompanies transport of CO2 in the blood (Chapter 1). In tissue capillaries, CO2 combines with free a-amino groups of hemoglobin to form carbaminohemoglobin in pulmonary capillaries, this reaction is reversed to release CO2 into the alveoli. This mode of transport is limited to only about 10% of the carbon dioxide transported in the blood. 

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X-Amino acids ate ampholytic compounds. The chemical reactions of amino acids can be classified according to their carboxyl, amino, and side-chain groups. Most of the reactions have been well known for a long time the details of these reactions have been reviewed (77). 

FUNCTIONAL GROUPS DICTATE THE CHEMICAL REACTIONS OF AMINO ACIDS... 

Predicting the Products of the General Chemical Reactions of Amino Acids... 

Understand the general chemical reactions of amino acids. (Problems 26.33 and 26.34)... 

Understand the general chemical reactions of amino acids. 

The chemical behavior of the amino acids is determined to a large extent by the functional groups in the side chains. In all work involving chemical reactions of amino acids the reactivities of the different side chains must be taken into account. Furthermore, even if the amino acids are comparatively stable molecules, easy to handle, unwanted decpmpositions and transformations may occur under comparatively mild conditions. The amino acids also show many intriguing possibilities for chemical reaction, some of which correspond to those occurring in biochemical pathways. 

A number of reactions of amino acids have become important in recent years because they are essential to the degradation, sequencing, and chemical synthesis of peptides and proteins. These reactions are discussed in Chapter 5. 

Each functional group of an amino acid exhibits all of its characteristic chemical reactions. For carboxylic acid groups, these reactions include the formation of esters, amides, and acid anhydrides for amino groups, acylation, amidation, and esterification and for —OH and —SH groups, oxidation and esterification. The most important reaction of amino acids is the formation of a peptide bond (shaded blue). 

A further pathway for the formation of specific individual hydrocarbons is that of the chemical degradation of amino acids. The reactions may be summarized as follows ... 

Goto, T., Futamura, Y., Yamaguchi, Y. et al. (2005). Condensation reactions of amino acids under hydrothermal conditions with adiabatic expansion cooling. Journal of Chemical Engineering of Japan, 38,4 295-9. 

Neurotransmitters include small molecules with amine functional groups such as acetylcholine, certain amino acids, amino acid derivatives, and peptides. Through a series of chemical reactions, the amino acid tyrosine is converted into the catecholamine neurotransmitters dopamine and norepinephrine or into the hormone epinephrine. Other neurotransmitters that are amino acid derivatives include y-aminobutyric acid, made from glutamate, and serotonin, made from the amino acid tryptophan. 

The pyridoxal phosphate (PLP)-dependent enzymes catalyze a diverse set of chemical transformations of amino acids. These include transamination, decarboxylation, and racemization reactions [Eqs. (41-43)],... 

Attempts have been made to study the active site by chemical modification of amino acid side chains (Messner e/ aL, 1970 Thrasher / a/., 1975 Thrasher and Cohen, 1971). No attempts have been made to separate the various products of the modification reactions and to study the individual homogeneous populations of modified proteins. Collectively, however, the results of these studies would appear to implicate an amino group in the cytophilic site. The data of Ciccimarra et al. (1975) suggest that there are two lysine residues in a decapeptide containing the site, but the positions of the modified amino groups have not been ascertained, nor has the effect of these reagents on other side chains and on conformations been studied. 

Heat heatment can also reduce the pH of the wood to a value of 3.5 [10], which might retard or accelerate the curing of adhesives, depending on the type of adhesive used for bonding. For instance, the acetic and formic acids which are present in wood after heat treatment might neutralize the alkaUne hardeners used for phenolic resins and hinder the adhesive hardening. On the other hand, a low pH of the wood surface could accelerate the chemical reactions of the acid catalyzed amino resins [31]. 

Chemical degradation of amino acids such as glutamin, cysteine reaction of amino-acids with glucose (Maillard reaction)... 

This chapter will present the most fundamental concepts for structure, nomenclature, and chemical reactions of amines. Biological applications will focus on the characteristics, formation, and reactions of amino acids. The use of amino acids in proteins and relatively simple reactions that form peptides will be discussed. In addition, several chemical reactions that lead to controlled degradation of peptides and proteins will be introduced. 

ARP from glycine, valine, diglycine, triglycine was synthesized by the method described by Sherr et al (1980) by the reaction of amino acid or peptide with glucose in methanol. Then, the ARP was purified using Dowex 50W-X4 column chromatography. The chemical structures were confirmed by MS and NMR. 

In each of these reactions, pyridoxal undergoes chemical alteration, sometimes with loss of its vitamin activity. In addition, pyridoxal in aqueous systems catalyzes a whole series of non-enzymatic reactions of amino acids in which p5u idoxal itself is unchanged. These reactions are as follow ... 

The applications of micromachined devices could be quite varied if the chips can be made versatile Performing chemical reactions on-chip is a key aspect of extending the versatility of these devices To this end we have demonstrated that a variety of device layouts can be used for mixing reagents on-chip, the first step in inducing a chemical reaction, and reaction of amino acids with a fluorescent label is presented... 

Description. These molecules are chemical derivatives of amino acids which can be produced by the reaction of chloroacetic acid or acrylic acid with an alkyl amine. 

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