Efficient nitrogen-13 radiochemistry catalyzed by a highly stable immobilized biocatalyst

Abstract

In the present work, an unprecedented strategy for the reduction of [13N]NO3− to [13N]NO2− using a heterogeneous biocatalyst will be presented.

Advanced characterization of immobilized enzymes as heterogeneous biocatalysts

“…New techniques like TOF-secondary ion mass spectrometry [20,101,108,131], solid-state NMR [21,73,[132][133][134][135], Foster resonance energy transfer (FRET) measurements [136] and Trp/Tyr fluorescence measurements [137,138] are gaining momentum, and exciting developments are expected in upcoming research. The direct characterization of the conformational properties of immobilized enzymes needs to be advanced through further method development.…”

Asymmetric Reduction of Prochiral Ketones by Using Self‐Sufficient Heterogeneous Biocatalysts Based on NADPH‐Dependent Ketoreductases

“…We reasoned that the alkaline pH may cause enzyme inactivation, whichoccurs with other enzymes immobilized on agarose beads through the same chemistry and under similarc onditions. [40] To confirm that KRED did not undergo anys tructurald istortion upon its immobilization on Ag-DEAE, we measuredt he intrinsic fluorescences pectrum of this protein in both solubilized and immobilized forms (see the Supporting Information, Figure S1A and Ta ble S1). The aldehyde chemistry requires am ild reduction step upon immobilization to turn the reversible enzyme-carrier iminebonds into irreversibles econdary amines.…”

“…[12,15] However,i nb oth approaches, it is still necessary to add the cofactor exogenously,w hich increases the process costs and complicates the workup upon reaction completion. [29] This strategy has been demonstrated successfully in asymmetricr eductions that werec atalyzed by KREDs in organic media; however,i tf ailed in aqueous media owing to the lixiviation of both NADH and enzymes. This approach enabled the successful integration of NAD(P)H-dependent enzyme systemsi nto ultrafiltration membrane reactors for continuous reduction processes, which mitigated the addition of exogenous cofactors.…”

Chemistry for Positron Emission Tomography: Recent Advances in 11C‐, 18F‐, 13N‐, and 15O‐Labeling Reactions

“…[211,[214][215][216] [ 13 N]NO 2 À is another commonly used synthon for 13 N chemistry,w hich can be prepared by proton irradiation of water, oxidation of [ 13 N]NH 3 using gallium or cobalt oxides,or reduction of [ 13 N]NO 3 À by metals or eukaryotic nitrate reductase (Scheme 37 A). [211,217,218] The 13 N-nitrosation of ureas,s econdary amines,a nd thiols could be realized with [ 13 N]NO 2 À . [217,219] Forexample,GSNO,amost widely studied S-nitrosothiol, was synthesized in 24 %RCY.…”