Fitting Proteins into Metal Organic Frameworks

Proteins are no longer just ingredients for biologists: Proteinaceous materials are gradually stepping into the spotlight as highly functional next generation materials, despite the fact that “material science” has previously mainly been explored by chemists. In the September 16th issue of Journal of American Chemical Society, Tezcan and co-workers report an interesting methodology to prepare a novel three-dimensional (3D) protein crystalline material utilizing the metal organic framework (MOF) approach (Figure 1). This work has the potential to be a milestone for the next decade, as these proteinaceous MOFs may overcome several major drawbacks of conventional proteinaceous materials. Obviously, the most attractive feature to using protein building blocks to forge 3D porous materials is the wide variety of structures and functions that inherently exist in proteins, particularly catalysis, electron transfer, and molecular recognition. Emulating protein function with synthetic molecules remains a daunting challenge, and thus, fabricating materials with proteins incorporated has so far best provided the benefit of proteins’ stunning functions. There have already been several successful attempts to directly exploit some porous protein single crystals as materials toward specific purposes. These more typical protein crystals rely structurally on weak surface intermolecular interactions, meaning they are unstable. Poor mechanical strength is an unavoidable limitation to the scope of their application. When the crystallization conditions were optimized, the authors obtained the world’s first proteinaceous MOF crystal, and a rare rationally designed crystal structure.