Reagent Proteins: Reagent Proteins is the Source for Proteins. Supplying over 5,000 quality reagent proteins, specialized products and vaccine components. Formerly sold under the Reagent Proteins division of Pfenex, CRM197 is the ideal carrier protein or immunological adjuvant for conjugate vaccines. CRM197 has been used commercially in prophylactic vaccines since 1990. Current research and development areas include immunotherapies and anti-addiction vaccines. Pfenex CRM197 is similar in both structure and function to the protein produced in C. diphtheriae, as shown in physicochemical and in vivo studies.