In addition to determining the specific activity toward ABTS, we evaluated the transformation product of AFB1 by both enzymes using LCMS (Figure ). The observed product of the oxidation reaction between AFB1 and the laccase had a molar mass of 329 g/mol when run in positive mode, exactly 16 more than AFB1's weight of 313 g/mol, suggesting that a net gain of one oxygen is likely. This directly supports the previous findings by Guo, et al. that claimed AFB1 was oxidized to AFQ1 when exposed to their laccase. As previously stated, these enzymes have a very dissimilar primary structure, only 13% sequence similarity, but they both seem to catalyze the same reaction. This points to a strong biochemical reason why they may have the same product. Highly conserved catalytic residues and AFB1's physiochemical properties may lead to a funneling of possible products from the reaction to a common result. To further understand the structural determinants of function for these enzymes, molecular modeling studies were utilized to evaluate potential interactions that lead to catalytically competent AFB1 binding modes. To determine which atoms are likely to undergo oxidation, density functional theory (DFT) calculations were carried out using GAUSSIAN16. Geometric optimization and frequency calculations for the AFB1 radical cation INT1 (Figure ) and radical INT2 (Figure ) were performed with PCM (water)-M06L/6-31+G(d,p). The absence of any imaginary frequencies confirmed that these structures are minima on the potential energy surface (PES). Spin density values were extracted from the optimized geometries, and a working mechanism leading to the known product AFQ1 was proposed (Figure ). Based on the calculated spin density of radical cation INT1, the initial single electron transfer (SET) from neutral AFB1 to His 458 will lead to a structure with significant spin density on carbons 7, 8, 9, 12, and 14 (spin density in blue in Figure ). Since C7, C10, C12, and C14 are connected through conjugation, we hypothesize the first SET involves this π-system, removing an electron to create INT1 (Fig. ). Next, we posit that a deprotonation occurs at C3 by a general base, forming INT2, which subsequently undergoes another SET. Based on the calculated spin density values for INT2 (Figure ), the second SET most likely generates an allylic cation, INT3. Optimization and frequency calculations were performed on INT3 as well, verifying it is a minimum on the PES. Subsequently, water adds to the less sterically hindered C3 on INT3, followed by a proton transfer, forming AFQ1. Based on modeling and the consistency of the product being formed in experimental results, it is hypothesized that 2 AFB1 molecules are oxidized to AFQ1 for each reduction of O2 to 2H2O. It should be noted that none of the laccases in this study with solved crystal structures contained an acidic amino acid in a catalytically relevant orientation in the active site, which may explain why many of these enzymes were highly active on the reporter substrate while having extremely slow reactivity with AFB1.