SCCUR_poster_larry
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Protein (MW kDa) Soln Properties: Salt Conc., pH Hydration Ion Binding BSA (66.5) 0.15 M NaCl, 4.5 0.15 M NaCl, 5.4 0.15 M NaCl, 7.4 1.113 ± 0.0063 1.137 ± 0.0059 1.177 ± 0.0050 11.59 [2] 10.62 [2] 8.81 [2] Effect of Monovalent Salt Anions on the Osmotic Pressure of Bovine Serum Albumin Larry Chang, Danielle N. Ornelas, Noriko Uka Ozaki-Felt, Victor G. J. Rodgers Department of Bioengineering, University of California, Riverside References 1. Yousef MA, Datta R, Rodgers VGJ. AIChE J. 2002; 48:913-917. 2. Yousef MA, Datta R, Rodgers VGJ. J Colloid Interface Sci. 1998; 207:273-282. 3. Yousef MA, Datta R, Rodgers VGJ. J Colloid Interface Sci. 2001; 243:321-325. 4. Reboiras MD, Pfister H, Pauly H. Biophysical Chemistry. 1986; 24:249-257. 5. Scatchard G, Scheinberg IH, Armstrong SH. J Am Chem Soc. 1950; 72:535-540. 6. Zhang Y and Cremer PS. Current Opinion Chem Bio. 2006; 10:658-663. › The presence of anions alters osmotic pressure and the overall hydration of the system. › The FSM was able to calculate ion binding and hydration with reasonable error. › Ion binding and hydration is not monotonically consistent with the Hofmeister series. › Results show that our experimentally determined ion binding values were significantly different than those calculated by Reboiras et al. and Scatchard et al. › Further osmotic pressure data is needed for high BSA concentrations up to saturation limit in NaI. Sensitivity of the model increases as BSA concentration increases . › Further osmotic pressure data will be gathered for BSA in 0.15 M NaF, NaCl, NaI, and NaSCN at pH 4.5. T h e B 2 K G r o u p │ B I O T R A N S P O R T & B I O R E A C T I O N K I N E T I C S For additional information, please contact Dr. Victor G. J. Rodgers at [email protected]. CO 3 2- SO 4 2- S 2 O 3 2- H 2 PO 4 - F - Cl - Br - NO 3 - I - ClO 4 - SCN - Discussion and Future Work Aggregation Solubilization Objective The free-solvent model predicts the non-linear protein osmotic pressure of concentrated protein solutions at moderate ionic strength. Here, we investigate how anions affect the osmotic pressure of bovine serum albumin (BSA) in the presence of 0.15 M NaCI, NaF, NaI and NaSCN at pH 7.4. Osmotic pressure data are obtained up to saturation. Using non-linear least squares regression, we are able to predict the model parameters of ion binding and hydration values. The results will allow further understanding of how osmotic pressure is coupled to ion binding and hydration relative to the Hofmeister series. Free-Solvent Model (FSM) pH Dependence of Ion Binding Observed from Osmotic Pressure Hofmeister Series Literature F - , Cl - , I - , and SCN - Ion Binding to Albumin Ion Binding and Hydration of 0.15 M Salt Solutions Osmotic Pressure of Bovine Serum Albumin (BSA) The FSM was developed to describe non-ideal behavior of proteins at high concentrations. FSM is an ideal model that places emphasis on the hydrated macromolecule. The FSM considers the non-attractive interactions between macromolecules and the remaining free solvent. There are two biologically significant parameters that are independently determined when predicting protein osmotic pressure; protein hydration, v 1j, and salt ion binding, v 3j .The mole fraction of diffusible species, , is also critical when determining the prediction of osmotic pressure. Studies previously conducted by Yousef et al. showed that while the hydration values are relatively consistent, the salt ion binding values were sensitive among varying pH. However, salt ion and albumin interactions are limited due to the number of charged surface residues. The Hofmeister series is a classification of ions in order of their ability to salt out or salt in proteins. The early members of the series decrease the solubility of nonpolar molecules, strengthening the hydrophobic interactions. The later salts increase the solubility of nonpolar molecules, while weakening the hydrophobic effect. Reboiras et al. utilized an empirical model to examine the binding of potassium salts to BSA at high protein concentrations. Scatchard et al. developed an empirical model for providing expected ion binding of sodium chloride to human serum albumin (HSA). 1: water 2p: proteins (p+1)n: salt I: solvent chamber II: protein chamber 36 psi Ion Soln Properties: Salt Conc. [M] Ion Binding Soln. Properties: Salt Conc. [M] Ion Binding F - 0.1 3 [4] 0.3 -2 [4] Cl - 0.1 6 [4] , 8 [5] 0.3 3 [4] , 12 [5] I - 0.1 11 [4] 0.3 16 [4] Theoretical Saturation Limit Soln Properties: Salt Conc., pH Ion Binding Hydration 601.32 0.15 M NaF, 7.4 0.15 M NaF, 7.4 6.18 ± 0.645 3 [4] 0.927 ± 0.037 0.696 ± 0.014 544.96 0.15 M NaCl, 7.4 6.79 ± 0.658 1.099 ± 0.033 724.11 0.15 M NaI, 7.4 0.15 M NaI, 7.4 -0.29 ± 1.156 11 [4] 0.645 ± 0.054 1.175 ± 0.010 Soln Properties: Salt Conc., pH Second Virial Coefficient, β 2 × 10 -7 Ionic Strength Ionic Strength Ratio, α 0.15 M NaF, 7.4 2.4 0.100 0.667 0.15 M NaCl, 7.4 4.8 0.093 0.621 0.15 M NaI, 7.4 2.6 -0.007 -0.045 *At 400 g/L protein concentration. 2 2 BSA g O H g 2 BSA mol Salt mol BSA mol Salt mol BSA mol Salt mol BSA mol Salt mol BSA g O H g 2
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Transcript of SCCUR_poster_larry
Protein (MW kDa) Soln Properties:Salt Conc., pH
Hydration Ion Binding
BSA (66.5)0.15 M NaCl, 4.50.15 M NaCl, 5.40.15 M NaCl, 7.4
1.113 ± 0.00631.137 ± 0.00591.177 ± 0.0050
11.59[2]
10.62[2]
8.81[2]
Effect of Monovalent Salt Anions on the Osmotic Pressure of Bovine Serum Albumin
Larry Chang, Danielle N. Ornelas, Noriko Uka Ozaki-Felt, Victor G. J. RodgersDepartment of Bioengineering, University of California, Riverside
References1. Yousef MA, Datta R, Rodgers VGJ. AIChE J. 2002; 48:913-917.2. Yousef MA, Datta R, Rodgers VGJ. J Colloid Interface Sci. 1998; 207:273-282.3. Yousef MA, Datta R, Rodgers VGJ. J Colloid Interface Sci. 2001; 243:321-325.4. Reboiras MD, Pfister H, Pauly H. Biophysical Chemistry. 1986; 24:249-257.5. Scatchard G, Scheinberg IH, Armstrong SH. J Am Chem Soc. 1950; 72:535-540.6. Zhang Y and Cremer PS. Current Opinion Chem Bio. 2006; 10:658-663.
› The presence of anions alters osmotic pressure and the overall hydration of the system.
› The FSM was able to calculate ion binding and hydration with reasonable error.
› Ion binding and hydration is not monotonically consistent with the Hofmeister series.
› Results show that our experimentally determined ion binding values were significantly different than those calculated by Reboiras et al. and Scatchard et al.
› Further osmotic pressure data is needed for high BSA concentrations up to saturation limit in NaI. Sensitivity of the model increases as BSA concentration increases .
› Further osmotic pressure data will be gathered for BSA in 0.15 M NaF, NaCl, NaI, and NaSCN at pH 4.5.
T h e B 2 K G r o u p │ B I O T R A N S P O R T & B I O R E A C T I O N K I N E T I C S
For additional information, please contact Dr. Victor G. J. Rodgers at [email protected].
CO32- SO4
2- S2O32- H2PO4
- F- Cl- Br- NO3- I- ClO4
- SCN-
Discussion and Future Work
Aggregation Solubilization
ObjectiveThe free-solvent model predicts the non-linear protein osmotic pressure of concentrated protein solutions at moderate ionic strength. Here, we investigate how anions affect the osmotic pressure of bovine serum albumin (BSA) in the presence of 0.15 M NaCI, NaF, NaI and NaSCN at pH 7.4. Osmotic pressure data are obtained up to saturation. Using non-linear least squares regression, we are able to predict the model parameters of ion binding and hydration values. The results will allow further understanding of how osmotic pressure is coupled to ion binding and hydration relative to the Hofmeister series.
Free-Solvent Model (FSM)
pH Dependence of Ion Binding Observed from Osmotic Pressure
Hofmeister Series
Literature F-, Cl-, I-, and SCN- Ion Binding to Albumin
Ion Binding and Hydration of 0.15 M Salt Solutions
Osmotic Pressure of Bovine Serum Albumin (BSA)
The FSM was developed to describe non-ideal behavior of proteins at high concentrations. FSM is an ideal model that places emphasis on the hydrated macromolecule. The FSM considers the non-attractive interactions between macromolecules and the remaining free solvent. There are two biologically significant parameters that are independently determined when predicting protein osmotic pressure; protein hydration, v1j, and salt ion binding, v3j.The mole fraction of diffusible species, , is also critical when determining the prediction of osmotic pressure.
Studies previously conducted by Yousef et al. showed that while the hydration values are relatively consistent, the salt ion binding values were sensitive among varying pH. However, salt ion and albumin interactions are limited due to the number of charged surface residues.
The Hofmeister series is a classification of ions in order of their ability to salt out or salt in proteins. The early members of the series decrease the solubility of nonpolar molecules, strengthening the hydrophobic interactions. The later salts increase the solubility of nonpolar molecules, while weakening the hydrophobic effect.
Reboiras et al. utilized an empirical model to examine the binding of potassium salts to BSA at high protein concentrations. Scatchard et al. developed an empirical model for providing expected ion binding of sodium chloride to human serum albumin (HSA).
BSA g
OH g 2
BSA mol
Salt mol
1: water2p: proteins(p+1)n: saltI: solvent chamberII: protein chamber
36 psi
Ion Soln Properties:Salt Conc. [M]
Ion Binding Soln. Properties:Salt Conc. [M]
Ion Binding
F- 0.1 3[4] 0.3 -2[4]
Cl- 0.1 6[4], 8[5] 0.3 3[4], 12[5]
I- 0.1 11[4] 0.3 16[4]
BSA mol
Salt mol
BSA mol
Salt mol
TheoreticalSaturation Limit Soln Properties:
Salt Conc., pH
Ion Binding Hydration
601.32 0.15 M NaF, 7.40.15 M NaF, 7.4
6.18 ± 0.6453[4]
0.927 ± 0.0370.696 ± 0.014
544.96 0.15 M NaCl, 7.4 6.79 ± 0.658 1.099 ± 0.033
724.11 0.15 M NaI, 7.40.15 M NaI, 7.4
-0.29 ± 1.15611[4]
0.645 ± 0.0541.175 ± 0.010
Soln Properties:Salt Conc., pH
Second Virial Coefficient, β2 × 10-7
Ionic Strength Ionic Strength Ratio, α
0.15 M NaF, 7.4 2.4 0.100 0.667
0.15 M NaCl, 7.4 4.8 0.093 0.621
0.15 M NaI, 7.4 2.6 -0.007 -0.045
*At 400 g/L protein concentration.
BSA mol
Salt mol
BSA g
OH g 2
2
2
