Structural analogs of 5'-methylthioadenosine as substrates and inhibitors of 5'-methylthioadenosine phosphorylase and as inhibitors of human lymphocyte transformation

Michael W. White, Arthur A. Vandenbark, Carolyn L. Barney, Adolph J. Ferro

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5'-Deoxy-5'-methylthioadenosine (MTA) phosphorylase was purified 13.4-fold from human peripheral lymphocytes. The enzyme demonstrated normal Michaelis-Menten kinetics with Km values of 26 μM and 7.5 mM for the two substrates. MTA and phosphate, respectively. The rate of MTA degradation was temperature dependent, 47° being the optimum temperature. Five structural analogs served as alternative substrates with Km values ranging from 31 to 53 μM while two compounds, 5'-deoxy-5'methylthiotubercidin (MTT) (Ki = 31 μM) and adenine (Ki = 172 μM), were inhibitory. These same analogs were examined as inhibitors of mitogen-induced human lymphocyte blastogenesis. MTT was found to be the most effective inhibitor of lymphocyte transformation with an I50 of 80 μM.

Original languageEnglish (US)
Pages (from-to)503-507
Number of pages5
JournalBiochemical Pharmacology
Issue number4
StatePublished - Feb 15 1982


ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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