Study and design of amino acid-based radical enzymes using unnatural amino acids

Abstract

Radical enzymes harness the power of reactive radical species by placing them in a protein scaffold, and they are capable of catalysing many important reactions. New native radical enzymes, especially...

Near UV and Visible Light-Induced Degradation of Bovine Serum Albumin and a Monoclonal Antibody Mediated by Citrate Buffer and Fe(III): Reduction vs Oxidation Pathways

“…42 Fe(IV)�O reacts more selectively toward some amino acids, such as Tyr, Trp, Phe, and Met, and generally slower compared to • OH. 48,49 Based on the O 2 concentration in an air-saturated aqueous solution (250 μM, at 25 °C under atmospheric pressure) 67 and the added Fe(III) concentration (10 μM for most cases), reaction 1 is considered a minor pathway for • CO 2 − under our experimental conditions. Thus, in the following discussion, we will focus on the competition reactions of • CO 2 − with O 2 and disulfide bonds.…”

“…• CO 2 – can reduce Fe(III) to Fe(II) (reaction , k = 1.09 × 10 9 M –1 s –1 ) and reduce O 2 to O 2 •– (reaction , k = 2.4 × 10 9 M –1 s –1 ). , Reactions and provide an entry for the subsequent generation of ROS through reactions –, ,,− which can oxidize a large variety of organic molecules including amino acids. − In contrast, reactions and represent an efficient pathway for the reduction of protein disulfides, which has been reported for radiolysis studies. − ,− Notably, even an initial reduction of protein disulfide via reaction can lead to the generation of ROS if the initial disulfide radical anion (RSSR •– ) reacts with molecular oxygen via reaction rather than reaction . , Thus, • CO 2 – formed from the photodegradation of citrate-Fe(III) complex can result in competitive reactions between disulfide reduction and protein oxidation. normalC normal• O 2 − + Fe ( III ) → CO 2 + Fe ( II ) normalC normal• O 2 − + O 2 → CO 2 + normalO 2 • − ...…”