Homology principe (I)

This paper presents the principium of the homology used by the biosystems i n the alpha -aminoacidic structure formation. Are presented the structures of the alpha -aminoacids from the point of view of the radical nature. In t his order are presented alpha -aminoacids with alkylic radicals and with fu nctionalised alkylic radicals, such as alcohols, carboxylic acids, amines a nd ureic derivatives (all these function being placed in the final position ). Amino acids with ureic groups are considered peptides formed by the acyl ation of the aminic groups with carbamic acid, who is considered to have th e simplest amino-acidic structure (being formed only by the two caracterist ic function: the carboxyle and the amine) for this reason these molecules a re excluded from the codification. Are presented also alpha -amino-acids co ntaining branched alkylic radicals and cyclic alkylic radicals. Last group is the N-heterocyclic aminoacids. All structures of these series are discus sed in connection with four criteria: 1. if aminoacids are or not able to f orm peptidic linkage (L-P), 2. if aminoacids are or not proteic (proteine f ormators), 3. if aminoacids are or not included in the genetic code system, and 4. if aminoacids play or not any special metabolic role.