Binding and carrying role of human serum albumin from various sources to sphingosine-1-phosphate
Objective To investigate the binding and carrying effects of human serum albumin(HSA)from various sources on sphingosine-1-phosphate(S1P).Methods Utilizing human plasma-derived HSA(pHSA)and recombinant HSA(rHSA)samples as the focal points of our investigation,LC-MS/MS technology was employed to meticulously compare and an-alyze the disparities in S1P content among the aforementioned samples.Subsequently,under physiological concentration condi-tions,S1P was directly introduced to HSA samples for loading processing,facilitating a comprehensive comparison of the bind-ing efficacy of HSA from different sources to S1P.Within a serum-free culture setting,HSA samples from various sources were co-cultured with HUVEC cells.The alterations in S1P content within the cell culture supernatant across different treatment groups were meticulously analyzed,allowing for a nuanced comparison of the S1P carry effects exerted by HSA from different sources on cells.The interaction between HSA and S1P molecules from different sources was analyzed and their affinity was cal-culated using surface plasmon resonance(SPR)technology.Furthermore,leveraging AutoDock Vina software and the Mol-prophet platform,the molecular docking analysis of HSA and S1P was conducted,aiming to predict the key binding pocket do-main of S1P within HSA.Results All pHSA samples exhibited detectable levels of S1P(ranging from 3.31±0.03 to 30.35±0.07 μg/L),with significant variations observed among pHSA samples from different manufacturers(P＜0.001).Conversely,S1P was undetectable in all rHSA samples.Upon load treatment,the binding affinity of HSA from diverse sources to S1P dem-onstrated significant discrepancies(P＜0.001),with rHSA exhibiting approximately double the average S1P loading compared to pHSA(ΔCrHSA=801.75±142.45 μg/L vs ΔCpHSA=461.94±85.73 μg/L;P＜0.001,t=5.006).Co-culture treatment out-comes revealed a significant elevation in S1P concentration within the supernatant after 6 hours of co-culture across all HSA sample processing groups with HUVEC cells,while no changes were observed in the supernatant of the blank control group.Notably,significant differences in supernatant S1P concentration were observed among treatment groups at 6 h,12 h,and 24 h(P＜0.001).SPR analysis unveiled a stronger affinity of pHSA for S1P compared to rHSA(KDpHSA-S1P:2.38E-06,KDrHSA-S1P:3.72E-06).Molecular docking analysis and binding pocket prediction suggested that the key binding pocket of HSA and S1P may reside in the IB subdomain of the HSA molecule.Conclusion HSA from various sources exhibits distinct binding and carrying effects on S1P,which appear to be closely associated with the IB subdomain of the HSA molecule.
human serum albuminhuman plasma-derivedrecombinantsphingosine-1-phosphate(S1P)binding and carrying
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