The Inhibition Mechanism Research Of Thiadiazole Bridged Thioacetamide Compounds On Cy-FBP/SBPase And PCC6803

In today's world,many areas are plagued by water bloom and red tide caused by the massive outbreak of cyanobacteria.There are a lot of shortcomings of the algicide in use,such as poor selectivity and poor active.So we are always looking for a highly efficient,highly selective and environmentally friendly algicide algicide.In the early stage of this study,compound G3 with good inhibitory effect on Cy-FBP/SBPase was found by high-throughput screening,IC50=1.10?M.G3 was derivatized to the thiadiazole bridged thioacetamide G series compounds and constructed to the Y and Q series compounds.In this paper,we studied the inhibitory mechanism of inhibitor on Cy-FBP/SBPase.We measured the IC50 of three series of compounds on Cy-FBP/SBPase and found that the activity of G-series compounds on Cy-FBP/SBPase were superior to that of Y-series and Q-series(Q series conpounds essentially have no activity).This indicated that the integrity of the skeleton of G-series has a great impact on the activity of the compound.Both the thiadiazole heterocyclic ring and the symmetrical structure contribute to the activity of the enzyme.In order to further study the mechanism of the inhibition,we selected the compound G3 to measure the IC50 on the mutant.The IC50 of the mutant T102A and R176A in FBP cavity was reduced by about 1000 times,while the IC50 of the AMP cavity mutant did not change significantly.This indicates that our compound G3 acts on the FBP cavity of Cy-FBP/SBPase,and the mode of action of Cy-FBP/SBPase is similar to that of substrate FBP.We also conducted a study on the inhibitory mechanism of compounds on cyanobacteria.Firstly,we measured the EC50 of three series of compounds and found that each series had compounds with good activity,which were G2(EC50=0.46?M),Y3(EC50=0.08?M)and Q3(EC50=0.13 MM).Then,we determined the growth,the content of chlorophyll a and the rate of releasing oxygen,which indicated that our compounds had a strong inhibitory effect on photosynthesis during algae inhibition and algae killing.Finally,we performed RT-PCR and metabolite assay experiments.we found that compounds had a little potentiation on the transcription level of FBPase of cyanobacterium PCC6803,and G2 and Y3 seriously inhibited the formation of carbohydrate in PCC6803 photosynthesis.In summary,thiadiazole bridged thioacetamide G series compounds acted on the FBP cavity of Cy-FBP/SBPase,and the mode of action of Cy-FBP/SBPase is similar to that of substrate FBP.And G,Y and Q series compounds inhibited their growth by inhibiting the photosynthesis of cyanobacteria PCC6803.