Objective: Analysis of erythrocyte nucleotides is useful for diagnosing defects in purine salvage pathways. The aim of this work was to elucidate whether the investigation could be used in diagnosing defects of a second part purine de novo synthesis (PDNS). Dephosphorylated intermediates of the second part of PDNS (aminoimidazoleribosides) were used for membrane transport and biotransformation study. Material and Methods: Pathophysiological situation in patients suffering from defects of PDNS was simulated by incubation of native erythrocytes, erythrocyte membranes and erythrocyte lysates with dephosphorylated intermediates of second part of PDNS: 5-amino-4-imidazoleriboside (AIr), 5-amino-4-imidazolecarboxyriboside (CAIr), 5-amino-4- -imidazolesuccinocarboxamideriboside (SAICAr), 5-formylamino-4-imidazolecarboxamideriboside (FAICAr) a 5-amino- -4-imidazolecarboxamideriboside (AICAr). The compounds were synthesized and taken as standard compounds. Incubation mixtures were analyzed by capillary electrophoresis using three separation systems allowing analysis of both ribosides and ribotides. Results: Two of all studied ribosides (AICAr a FAICAr) were able to permeate through the erythrocyte membrane in detectable amounts. AICAr is an acceptable substrate for erythrocyte kinases and is converted to mono-, di- and triphosphates. Conclusions: The results suggest that erythrocytes are only useful for diagnosing AICAR-transformylase/IMPcyclohydrolase deficiency.

        Key words: aminoimidazoleribosides, purine de novo synthesis, membrane transport.