Comparative Analysis of Arylsulfatase and β-Glucuronidase in River and Wastewater: Insights into Deconjugation Behavior and Environmental Implications

Conjugated estrogens, including sulfate and glucuronide derivatives, are widely present in municipal wastewater and surface waters and may be enzymatically deconjugated to reactive free estrogens, posing ecological risks. However, the relative roles of arylsulfatase and β-glucuronidase in this process remain poorly understood, particularly in natural waters. Here, we systematically investigated the activity of these two enzymes in both river water and municipal wastewater as well as the deconjugation behavior of estrogen conjugates catalyzed by them. β-Glucuronidase activity was consistently higher than that of arylsulfatase across all samples, yet riverine enzymes exhibited significantly higher catalytic efficiency per unit activity than their wastewater counterparts. Deconjugation experiments using six estrogen conjugates revealed rapid hydrolysis of glucuronides and slow concentration-dependent hydrolysis of sulfates. Enzymatic kinetics further confirmed that substrate availability governs arylsulfatase activity, while β-glucuronidase shows a higher substrate affinity. These findings advance our understanding of contaminant reactivation processes and highlight the need to account for enzyme-mediated transformations when assessing the environmental fate and risks of conjugated emerging contaminants.