Amides biogenic

The amino group of cysteamine is bound to the carboxy group of another biogenic amine via an acid amide bond (-CO-NH-). [1-Alanine arises through decarboxylation of the amino acid aspartate, but it can also be formed by breakdown of pyrimidine bases (see p. 186). 

Acyl residues are usually activated by transfer to coenzyme A (2). In coenzyme A (see p. 12), pantetheine is linked to 3 -phos-pho-ADP by a phosphoric acid anhydride bond. Pantetheine consists of three components connected by amide bonds—pantoic acid, alanine, and cysteamine. The latter two components are biogenic amines formed by the decarboxylation of aspartate and cysteine, respectively. The compound formed from pantoic acid and p-alanine (pantothenic acid) has vitamin-like characteristics for humans (see p. 368). Reactions between the thiol group of the cysteamine residue and carboxylic acids give rise to thioesters, such as acetyl CoA. This reaction is strongly endergonic, and it is therefore coupled to exergonic processes. Thioesters represent the activated form of carboxylic adds, because acyl residues of this type have a high chemical potential and are easily transferred to other molecules. This property is often exploited in metabolism. 

Alkaloids with the piperidine nucleus, such as pelletierine (Punica grana-tum), lobelanine Lobelia inflata) and piperine Piper nigrum), have a typical biosynthesis pathway. It starts with L-lysine and continues via cadaverine (biogenic amine), A -piperideine and A -piperidinium cations and lobelanine, to be synthesized as lobeline. Piperine is synthesized from A -piperideine via piperidine (Figure 49). For the transformation from A -piperideine to A -piperideine cation, the residue from acetyl-CoA is needed, together with SAM activity in the transformation to lobelanine. Piperine is synthesized from piperidine through the formation of amide. 

The (S)-/ -Phe or (S)-/ -Tyr substructures of several spermidine alkaloids from plants, for example (S)-periphylline 43 [100, 101] or the spermine derivatives (S)-verbascenine 51 [101], aphelandrine 52 [102], chaenorhine 56 [103] and chae-norpine [104], hint at Michael addition of the biogenic amine to cinnamic acid 48 (or some oxidized equivalent, e.g. 49) within the /7-amino amide-forming step... 

There is also a possibility that aliphatic monoaldehydes generated in lipid autoxidation can participate in cross-linking of proteins. Formaldehyde can react in food systems with amino, amide, hydroxyl, and thiol groups in a.a. residues of proteins, even at room temperature. Some of these reactions result in cross-linking of the proteins. In cheese the biogenic formaldehyde reacts with the N-terminal His of y2-casein to form spinacine ... 

Protoalkaloids are bases with a simple structure, e.g. the biogenic amines, which are formed by decarboxylation or N-methylation of an amino acid (tyramine, histamine, choline, ephedrine, mescaline). Capsaicin, which is the amide of vanillylamine (4-hydroxy-3-methoxybenzylamine), has also been included in this group. 

For analytical purposes, amines espedaUy biogenic amines, are frequently derivatized using N-dimethylnaphthalenesulfonylchloride to form the so-called dansyl amides. These derivatives generate the N-dimethylaminonaphthalene ion at m/z 171 upon electron impact ionization, especially ih the case of low energy electrons . Thus, the transition m/z (171 + SOj -f- amine — 1) 171 was applied... 

Histamine is a biogenic amine formed by L-histidine decarboxylation mediated by HDC (histidine decarboxylase) (EC EC 4.1.1.22) and naturally occurs in some fungi, marine, and plant species [6, 7]. It was isolated from aerial parts of Capsella bursa-pastoris (L.) Medik. (Brassicaceae), Lolium perenne L. (Poaceae) [8], and Spinacea oleracea L. (Chenopodiaceae) [7, 9]. This amine may act as an intermediate in many imidazole derivatives biosynthesis such as amides. 

Substituted amides derived from amino acids (biogenic amines) and cinnamic acids are also frequent components. Amides derived from biogenic amines are constituents of cell walls of higher... 

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