DMSO can be used as a cosolvent to help dissolve poorly water-soluble substrates in enzyme reactions. The useful concentration is the one that supports product formation while preserving sufficient catalyst activity.
Solubility and enzyme performance belong together
Better substrate dissolution can improve access to the catalyst, but DMSO can also change enzyme activity, stability and selectivity. The response depends on the enzyme, substrate and reaction mixture.
Research on ene reductases shows that solvent tolerance depends on how performance is measured. A thermal-stability result alone does not establish how long an enzyme will perform in a particular solvent-containing reaction.
Establish the working concentration
Compare a DMSO concentration series with a solvent-free or established-process control. State whether the percentage is by volume or mass, and keep substrate loading, enzyme loading, buffer and reaction time comparable.
Measure product formation and retained activity under operating conditions. Whole-cell systems also require assessment of cell viability and transport. Include DMSO introduced through substrate or reagent stock solutions in the final concentration.
Use consistent solvent quality and handling between batches.
For sourcing, share the DMSO specification established for your biocatalytic system with YUJI.