Chitin- and Streptavidin-Mediated Affinity Purification Systems: A Screening Platform for Enzyme Discovery.

Affinity purification of recombinant proteins is an essential technique in biotechnology. However, current affinity purification methods are very cost intensive, and this imposes limits on versatile use of affinity purification for obtaining purified proteins for a variety of applications. To overcome this problem, we developed a new affinity purification system which we call CSAP (chitin- and streptavidin-mediated affinity purification) for low-cost purification of Strep-tag II fusion proteins. The CSAP system is designed to utilize commercially available chitin powder as a chromatography matrix, thereby significantly improving the cost-efficiency of protein affinity purification. We investigated the CSAP system for protein screening in 96-well format as a demonstration. Through the screening of 96 types of purified hemoproteins, several proteins capable of the catalytic diastereo-divergent synthesis of cyclopropanes were identified as candidates for an abiotic carbene transfer reaction.