Assay and Analysis of Dimethylsulfoniopropionate Demethylase

Abstract Dimethylsulfoniopropionate (DMSP) demethylase is a tetrahydrofolate-dependent enzyme that initiates the DMSP demethylation pathway in marine bacteria. This enzyme is important for understanding of organic sulfur flux from the oceans because it directs the sulfur from DMSP away from dimethylsulfide. This enzyme has been purified and characterized from two marine bacteria from different ecological niches. Both enzymes were confirmed to catalyze the tetrahydrofolate-dependent demethylation of DMSP and possessed similar properties. In this chapter a description of the steps for performing enzyme assays and measuring enzyme activity is provided.