Tyrosine structural classification

The side chains of the amino acids do not form a natural series, and thus, there is no easy way to learn their structures. It is useful to classify them according to whether they are polar or nonpolar, aromatic or aliphatic, or acidic or basic, although these classifications are not mutually exclusive. Tyrosine, for example, can be considered to be both aromatic and polar, although the polarity introduced by a single hydroxyl group in this aromatic compound is somewhat feeble. 

Patankar, S.J. and Jurs, P.C. (2003b) Classification of inhibitors of protein tyrosine phosphatase IB using molecular structure based descriptors. 

Presently, alkaloids are classified into three main categories as shown in Fig. 8.2 [6]. This chemical classification of alkaloids is universally adapted and mainly depends on the type of heterocyclic ring structure present (Fig. 8.3). Alkaloids are further classified according to the amino acids (or their derivatives) from which they originate (Fig. 8.4) [6]. The most important classes are derived from the amino acids, ornithine and lysine, or from the aromatic amino acids, phenylalanine and tyrosine, or from tryptophan and a moiety of mavelonoid origin. A number of alkaloid-based compounds are also derived from anthranilic acid or from nicotinic acid. 

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