It is generally considered that the pre-solvated electron and the solvated electron reacting with a solute yield the same product. Silver cyanide complex, Ag(CN), is used as a simple probe to demonstrate unambiguously the existence of a different reduction mechanism for pre-hydrated electrons. Using systematic multichannel transient absorption measurements at different solute concentrations from millimolar to decimolar, global data analysis and theoretical calculations, we present the dissociative electron attachment on Ag(CN). The short-lived silver complex, Ag(CN), formed by hydrated electron with nanosecond pulse radiolysis, can be observed at room temperature. However, at higher temperatures only the free silver atom, Ag, is detected, suggesting that Ag(CN) dissociation is fast. Surprisingly, pulse radiolysis measurements on Ag(CN) reduction, performed by a 7 ps electron pulse at room temperature, show clearly that a new reduced form of silver complex, AgCN, is produced within the pulse. This species, absorbing at 560 nm, is not formed by the hydrated electron but exclusively by its precursor. DFT calculations show that the different reactivity of the hydrated and pre-hydrated electrons can be due to the formation of different electronic states of Ag(CN): the prehydrated electron can form an excited state of this complex, which mainly dissociates into AgCN + CN.

Marine macroalgae, contributing much to the bioeconomy, have inspired tremendous attention as sustainable raw materials. Ulvan, as one of the main structural components of green algae cell walls, can be degraded by ulvan lyase through the β-elimination mechanism to obtain oligosaccharides exhibiting several good physiological activities. Only a few ulvan lyases have been characterized until now. This thesis explores the properties of a new polysaccharide lyase family 25 ulvan lyase TsUly25B from the marine bacterium Thalassomonas sp. LD5. Its protein molecular weight was 54.54 KDa, and it was most active under the conditions of 60 °C and pH 9.0. The Km and kcat values were 1.01 ± 0.05 mg/mL and 10.52 ± 0.28 s−1, respectively. TsUly25B was salt-tolerant and NaCl can significantly improve its thermal stability. Over 80% of activity can be preserved after being incubated at 30 °C for two days when the concentration of NaCl in the solution is above 1 M, while 60% can be preserved after incubation at 40 °C for 10 h with 2 M NaCl. TsUly25B adopted an endolytic manner to degrade ulvan polysaccharides, and the main end-products were unsaturated ulvan disaccharides and tetrasaccharides. In conclusion, our research enriches the ulvan lyase library and advances the utilization of ulvan lyases in further fundamental research as well as ulvan oligosaccharides production.