2026-10-14T11:03:50Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34028295 2026-09-30T00:04:51Z category_4 category_8 category_19 category_21 category_873 category_39 category_502 category_734 portal_63 item_type_6 month_year_09_2026

Dual Roles of Cyanopeptides as Substrates and Inhibitors of Enzymes in Surface Waters Xuejian Wang (532695) Elena Lippuner (25139574) Yaochun Yu (5570573) Elisabeth M. L. Janssen (9599929) Biochemistry Microbiology Pharmacology Biotechnology Chemical Sciences not elsewhere classified Ecology Astronomical and Space Sciences not elsewhere classified Biological Sciences not elsewhere classified probed underlying mechanisms cyanopeptolins inhibited trypsin compound assessments due investigated enzymatic reactions aquatic enzyme pool 2 ′- azinobis 2 μm ), 50 </ sub aquatic systems mediator 2 enzyme inhibitors surface waters oxidase activities organic compounds nostoginin bn741 mixtures compared mild inhibition microginin fr6 intact biofilm functional analogs dual roles containing microcystins analogous activities also formed abts ). Harmful cyanobacterial blooms produce diverse bioactive metabolites, cyanopeptides, whose environmental persistence remains uncertain. First, we investigated enzymatic reactions with cyanopeptides as substrates in aquatic systems. The aquatic enzyme pool from the riverine biofilm showed peptidase and oxidase activities. Incubation of cyanopeptides with the natural aquatic enzyme pool revealed novel transformation products (TPs) of two microginins (nostoginin BN741 and microginin FR6) and TPs of anabaenopeptins that also formed when incubated with intact biofilm. Next, we probed underlying mechanisms with peptidases as functional analogs of the aquatic enzyme pool. Carboxypeptidase Y produced identical hydrolysis TPs of the two microginins. A multicopper oxidase rapidly transformed tyrosine-containing microcystins, anabaenopeptins, and microginins, in the presence of the mediator 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS). Tyrosine-free congeners remained stable. Lastly, we investigated cyanopeptides as enzyme inhibitors. Cyanopeptolins inhibited trypsin (IC₅₀ = 53.75 nM), chymotrypsin (IC₅₀ = 2.2 μM), and analogous activities in the aquatic enzyme pool. Anabaenopeptins and microginins showed only mild inhibition of carboxypeptidase Y. As different cyanopeptides are co-produced by cyanobacteria, biotransformation is expected to differ in mixtures compared to single-compound assessments due to the observed inhibition taking place at the same time. Similarly, their release during bloom events may influence the transformation of other organic compounds in surface waters. 2026-09-29T00:00:00Z Text Journal contribution 10.1021/acs.est.6c07305.s001 https://figshare.com/articles/journal_contribution/Dual_Roles_of_Cyanopeptides_as_Substrates_and_Inhibitors_of_Enzymes_in_Surface_Waters/34028295 CC BY-NC 4.0