Selenomethionine incorporation is a standard method for determining the phases in protein crystallography by single- or multiwavelength anomalous dispersion. To support the efforts of scientists using this methodology, Expression Systems supplies a Methionine Deficient medium formulation. Se-Met incorporation levels are reported to be typically 75% (Protein Science 16(9):2023-9 · October 2007) but can range from 70-100% using this medium.

Structural biologists are increasingly utilizing NMR spectroscopy to obtain information about the structure and dynamics of proteins and their complexes. The simplest and most cost-effective biosynthetic labeling method for protein solid-state NMR is to uniformly label all carbon and nitrogen atoms with ¹³C and ¹⁵N. Expression Systems stocks an all amino acid deficient variant within the Delta series to enable scientists interested in adding a source of isotopically-labeled amino acids.