ADA2 isoform of adenosine deaminase from pleural fluid.

Adenosine deaminase isoenzyme 2 (ADA2) was isolated from human pleural fluid for the first time. Molecular and kinetic properties were characterized. It was shown that the inhibitors of adenosine deaminase isoenzyme 1 (ADA1), adenosine, and erithro-9-(2-hydroxy-3-nonyl)adenine (EHNA) derivatives are poor inhibitors of ADA2. Comparison of the interaction of ADA2 and ADA1 with adenosine and its derivative, 1-deazaadenosine, indicates that the isoenzymes have similar active centers. The absence of ADA2 inhibition by EHNA is evidence of a difference of these active centers in a close environment. The possible role of Zn2+ ions and the participation of acidic amino acids Glu and Asp in adenosine deamination catalyzed by ADA2 were shown.

Activity of adenosine deaminase and its isoforms in pleural fluid in tuberculous pleuritis.

BACKGROUND: The problem of tuberculosis is increasing in a number of countries. Adenosine deaminase activity is considered in many clinics to be a valuable biochemical test of this pathology. Considerable research has been devoted to the activity of enzyme isoforms as significant tests for diagnosing tuberculosis. The aim of our study was to compare the significance of different adenosine deaminase dependent parameters in diagnosing tuberculosis. MATERIAL/METHODS: The level of adenosine deaminase and the activity of its two isoenzymes in the pleural fluids of patients with tuberculous and non-tuberculous pleurisy were compared. RESULTS: The adenosine deaminase level in tuberculous pleural effusions was higher than in non-tuberculous pleural effusions. The data we obtained suggest that the enzyme activity level could be a very reliable test in the differential diagnosis of tuberculous pleurisy in the Armenian population. The activity of isoenzymes ADA1 and ADA2, or their ratios to the total ADA activity, though valuable information, has no diagnostic advantage over total ADA activity in diagnosing this pathology. CONCLUSIONS: The results clearly point up the value of using a total ADA activity assay in Armenian clinics for the differential diagnosis of tuberculous pleurisy. Determinations of the activity level of the ADA1 and ADA2 isoenzymes provide no diagnostic advantage over total ADA activity.