Poster abstracts
Poster number 106 submitted by Jeffrey Slater
Catalytic hydrogen production in artificial metalloenzymes
Jeffrey W. Slater (The Ohio State University), Haleigh A. Monaco (The Ohio State University), Sabrina L. Cirino (The Ohio State University)
Abstract:
The energy crisis of the last decade has opened the door for creative approaches to solve this urgent problem. Hydrogen has emerged as a leading candidate for an alternative fuel source. Towards this end, hydrogenases, which are enzymes that carry out the reversible reduction of protons into hydrogen gas, are of great interest, as they are often suggested for potential incorporation into a fuel cell and/or clean generation of hydrogen. By using proteins such as hydrogenases, which utilize cheap, abundant metals such as nickel or iron, we overcome the economic barrier of using rare earth metal catalysts such as platinum. However, these native hydrogenases are not well suited for general-purpose application due to their limited stability with respect to temperature and pH, rapid inactivation when exposed to oxygen, complexity of their biosynthesis, and limited potential for scalability and industrial application. Thus, we seek to accomplish chemistry similar to that performed by the [NiFe] hydrogenases by designing new functionality into a currently existing, robust metalloprotein.
Using Nature as inspiration, we seek to harness the advantages of
bioinorganic platforms while overcoming the limitations of large, fragile protein systems. One such platform is the small, electron-transfer protein rubredoxin (Rd). With its promiscuous metal-binding site, wide pH and thermal stability, and high recombinant expression yields, Rd is an optimum candidate for use in catalyst design. We will present results demonstrating that when the native, iron-bound protein is substituted with a nickel center, Rd can catalyze the reduction of protons electrocatalytically. Various techniques have been used to probe this activity and characterize catalytic intermediates, including protein film electrochemistry, electron paramagnetic resonance spectroscopy, and spectrophotometric redox titrations. Analogous to native hydrogenases, nickel-substituted Rd has also been shown to coordinate small organometallic moieties such as CO and CN-. By manipulating nickel- substituted Rd, we hope to create a robust metalloenzyme and obtain insight into the key parameters required for catalytic hydrogen production and oxidation.
References:
Slater, J. W.; Shafaat, H. S. Nickel-substituted rubredoxin is an effective electrocatalyst for hydrogen production 2015 (In review)
Keywords: Hydrogen, Metalloenzyme, Electrochemistry