title: Inactivation of S-adenosylhomocysteine hydrolase during adenine arabinoside therapy.
abstract: To assess for possible inhibition of cellular transmethylation during adenine arabinoside (ara-A) therapy, S-adenosylhomocysteine hydrolase activity was analyzed in 10 patients with chronic hepatitis B virus infection. In six patients receiving ara-A, enzyme activity was suppressed to 0-2% of control erythrocyte enzyme activity. This decrease in enzyme activity was evident within 4 h of starting the drug infusion and continued for 7 d after cessation of therapy. S-adenosylhomocysteine hydrolase activity of peripheral mononuclear cells was also measured in two patients receiving ara-A. Suppression to as low as 3.5% of pretreatment levels was found; however, marked fluctuations with partial return of enzyme activity during therapy was also observed in mononuclear cells. Inhibition of an enzyme involved in transmethylation reactions was observed in patients during ara-A therapy. This could contribute to the side effects and antiviral properties of ara-A.
mesh_terms: D043383:Adenosylhomocysteinase; D004912:Erythrocytes / Q000201:enzymology; D006801:Humans; D006867:Hydrolases / Q000097:blood*; D008214:Lymphocytes / Q000201:enzymology; D013997:Time Factors; D014740:Vidarabine / Q000009:adverse effects*
chemical_list: D006867:Hydrolases; D043383:Adenosylhomocysteinase; D014740:Vidarabine