RESUMEN
Adenosine deaminase [ADA] is one of the key enzymes in purine nucleotide degradation. This enzyme exists in most of the human tissues, its activity is high in lymphatic tissues, especially in T lymphocytes. To determine the effect of divalent elements on ADA activity in normal and abnormal cerebrospinal fluid. ADA activity in C.S.F was estimated by Galanti and Guisti coloremetric method, read at 628 nm. and the effect of divalent elements on ADA activity in normal and abnormal C.S.F was studied, by using 0.015 M of each solution of [Mg[2+], Co[2+], Cu[2+], Zn[2+], Mn[2+], Fe[2+], Ca[2+]]. All elements, except Mg[2+], have an inhibitory effects ranging from slight inhibition caused by Ca[2+], which gave 95.24% activity after inhibition, till the strong inhibition caused by Cu[2+] which gave 32.31% activity. Although Mg[2+] was found to have an activating effect. In addition, the activity percentage of ADA after inhibition was decreased simultaneously with the increasing of Cu[2+] concentration.The inhibitory effect of Cu[2+] on ADA activity in abnormal C.S.F was higher than that in normal C.S.F. The same resuls was shown in the effect of Co[2+]. ADA activity in normal C.S.F was inhibited by the effect of several divalent elements, the inhibitary effect of Co[2+] and Cu[2+] on ADA activity in abnormal C.S.F was than in normal