Esterase Activity of Serum Albumin Studied by 1H NMR Spectroscopy and Molecular Modelling

Abstract

Serum albumin possesses esterase and pseudo-esterase activities towards a number of endogenous and exogenous substrates, but the mechanism of interaction of various esters and other compounds with albumin is still unclear. In the present study, proton nuclear magnetic resonance (1H NMR) has been applied to the study of true esterase activity of albumin, using the example of bovine serum albumin (BSA) and p-nitrophenyl acetate (NPA). The site of BSA esterase activity was then determined using molecular modelling methods. According to the data obtained, the accumulation of acetate in the presence of BSA in the reaction mixture is much more intense as compared with the spontaneous hydrolysis of NPA, which indicates true esterase activity of albumin towards NPA. Similar results were obtained for p-nitophenyl propionate (NPP) as substrate. The rate of acetate and propionate release confirms the assumption that there is a site of true esterase activity in the albumin molecule, which is different from the site of the pseudo-esterase activity Sudlow II. The results of molecular modelling of BSA and NPA interaction make it possible to postulate that Sudlow site I is the site of true esterase activity of albumin.

Exploring the Specific Role of Iron Center in the Catalytic Activity of Human Serum Transferrin: CTAB-Induced Conformational Changes and Sequestration by Mixed Micelles

“…Apart from UV–vis studies, we have characterized the final product, para -nitrophenolate, using time-dependent nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, and the results are in line with literature reports (Figures S9 and S10). − Interestingly, we observed that, with the addition of 20 mM CHAPS/NaC/NaDC to the Fe-hTF/CTAB system, the reaction kinetics of the esterase-like activity of Fe-hTF was extremely attenuated, and no appreciable catalysis was observed as evident from their nonvariant absorption kinetic traces (Figures b,c and S11a–c). Several control experiments have also been performed to unveil the predominant role of CTAB in accelerating the reaction kinetics of the esterase-like activity of the protein, as demonstrated in Figure S12a,b.…”

Insight into the Effect of Submicellar Concentrations of Sodium Deoxycholate on the Structure, Stability, and Activity of Bovine and Human Serum Albumin: An Interesting Comparison between Single and Double Tryptophan Proteins

“…PNPA, a classical substrate of carboxylesterase, is widely used to study the esterase activity of serum albumins. Usually, the protein hydrolyzes PNPA to produce yellow-colored p -nitrophenol, which can easily be detected by monitoring the absorbance at 400 nm. , On increasing concentration of NaDC, the esterase activity of both BSA and HSA was found to decrease, suggesting the effect of NaDC on the native structure of the serum albumins (Figure ). In a recent study, Belinskaia et al have proposed that Tyr149 in Sudlow site I of BSA (Tyr150 for HSA) is actively involved in the esterase activity of the serum albumins .…”

“…Usually, the protein hydrolyzes PNPA to produce yellow-colored p -nitrophenol, which can easily be detected by monitoring the absorbance at 400 nm. , On increasing concentration of NaDC, the esterase activity of both BSA and HSA was found to decrease, suggesting the effect of NaDC on the native structure of the serum albumins (Figure ). In a recent study, Belinskaia et al have proposed that Tyr149 in Sudlow site I of BSA (Tyr150 for HSA) is actively involved in the esterase activity of the serum albumins . Therefore, the decrease in the esterase activity of these proteins in the presence of NaDC can be attributed to the alteration in the microenvironment of the tyrosines by NaDC, which has also been observed from SFS studies.…”

The impact of nano-polystyrene on human serum albumin–paracetamol interactions: understanding the impact on therapeutic development and safety

“…47 The binding energies of polystyrene and paracetamol were equal only at Sudlow site II. 26 Even though the binding energies were the same, this might not be the case for larger polystyrene molecules such as NPS. The NPS has thousands of polystyrene molecules that can interact with multiple residues at the same time, causing even stronger binding.…”

“…A docking study was performed using AutoDock 1.5.6. 26 The protein molecule was prepared for docking by the deletion of water, followed by the addition of Kollman charges and hydrogens. The ligand and protein molecules were saved as pdbqt files.…”