Acrylamide Production Using Encapsulated Nitrile Hydratase from \u3cem\u3ePseudonocardia thermophila\u3c/em\u3e in a Sol–gel Matrix

The cobalt-type nitrile hydratase from Pseudonocardia thermophila JCM 3095 (PtNHase) was successfully encapsulated in tetramethyl orthosilicate sol–gel matrices to produce a PtNHase:sol–gel biomaterial. The PtNHase:sol–gel biomaterial catalyzed the conversion of 600 mM acrylonitrile to acrylamide in 60 min at 35 °C with a yields of \u3e90%. Treatment of the biomaterial with proteases confirmed that the catalytic activity is due to the encapsulated enzyme and not surface bound NHase. The biomaterial retained 50% of its activity after being used for a total of 13 consecutive reactions for the conversion of acrylonitrile to acrylamide. The thermostability and long-term storage of the PtNHase:sol–gel are substantially improved compared to the soluble NHase. Additionally, the biomaterial is significantly more stable at high concentrations of methanol (50% and 70%, v/v) as a co-solvent for the hydration of acrylonitrile than native PtNHase. These data indicate that PtNHase:sol–gel biomaterials can be used to develop new synthetic avenues involving nitriles as starting materials given that the conversion of the nitrile moiety to the corresponding amide occurs under mild temperature and pH conditions

A Departmental Focus on High Impact Undergraduate Research Experiences

Undergraduate research experiences have become an integral part of the Hamilton College chemistry experience. The major premise of the chemistry department’s curriculum is that research is a powerful teaching tool. Curricular offerings have been developed and implemented to better prepare students for the independence required for successful undergraduate research experiences offered during the academic year and the summer. Administrative support has played a critical role in our ability to initiate and sustain scholarly research programs for all faculty members in the department. The research-rich curriculum is built directly upon or derived from the scholarly research agendas of our faculty members. The combined strengths and synergies of our curriculum and summer research program have allowed us to pursue several programmatic initiatives

Spectroscopic and Electrochemical Properties of (\u3cem\u3eμ\u3c/em\u3e-Oxo)diiron(III) Complexes Related to Diiron-Oxo Proteins. Structure of [Fe\u3csub\u3e2\u3c/sub\u3eO(TPA)\u3csub\u3e2\u3c/sub\u3e(MoO)\u3csub\u3e4\u3c/sub\u3e)](ClO\u3csub\u3e4\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e

A series of (μ-oxo)diiron(III) complexes of tris(2-pyridylmethy1)amine (TPA), [Fe2O(TPA)2(L)] (C1O4)2, were synthesized and characterized where L represents the bridging tetraoxo anion ligands sulfate, phosphate, arsenate, vanadate, and molybdate. These tetraoxo anion complexes are the first (μ-oxo)diiron(III) complexes that reproduce the protein-tetraoxo anion stoichiometry found in purple acid phosphatases (PAPs). [Fe2O(TPA)2( MoO4)] (C104)2- CH3N (9) crystallizes in the monoclinic space group P21/n (a = 12.74(1) Å, b = 24.69(2) Å, c = 13.733(8) Å, β = 103.41 (7)°, and Z = 4) and consists of two distinct six-coordinate Fe(II1) centers bridged by oxo and molybdate. 9 represents the first (μ-oxo)diiron(III) complex with a single bridging molybdate to be structurally characterized. These new complexes together with previously reported (μ-oxo)diiron(III) TPA complexes constitute a series with a wide range of Fe-μ-0-Fe angles and bridging anion basicities which affect their electronic absorption, resonance Raman, and electrochemical properties. A linear correlation between the Raman vs(FeO-Fe) mode and the energy of the long-wavelength visible absorption band provides a method in which UV-vis spectroscopy can be used to estimate the Fe-O-Fe angle. The electrochemical properties of these complexes show the expected dependence on charge and basicity and thus serve as a basis on which to interpret the redox properties of diiron-xo proteins, particularly uteroferrin, the purple acid phosphatase from porcine uterus. Comparison of the electrochemical properties of the phosphate, arsenate ,and molybdate complexes in the (μ-oxo)diiron(III) TPA series with those of corresponding complexes of uteroferrin suggests that both phosphate and arsenate bridge the diiron core in uteroferrin, while molybdate must bind only to the redox inactive Fe(II1) center. The mixed-valent forms of several of these complexes exhibit EPR signals with gaav \u3c 2, like those observed for the mixed-valent diiron enzymes but with smaller g anisotropies