Phenylmethylsulfonyl fluoride protects L-lysine transport in Schizosaccharomyces pombe against inactivation by ammonium ions.

Ammonium ions inactivate the basic amino acid transport system in Schizosaccharomyces pombe in an irreversible manner. The inactivation is accompanied by a 4-fold decrease of KT of L-lysine transport, leaving its Jmax unchanged; phenylmethylsulfonyl fluoride protects the system against inactivation. In contrast, two basic amino acid transport systems in a gap1 mutant of Saccharomyces cerevisiae are influenced by NH4+ ions in such a way that only the Jmax decreases while the KT of L-lysine transport is unchanged. Phenylmethylsulfonyl fluoride does not act here as a protective agent.