Protein partitioning

Schiff base fonnation, photochemistry, protein partitioning, catalysis by chymotrypsin, lipase, peroxidase, phosphatase, catalase and alcohol dehydrogenase. 

R. Consden, A. H. Gordon and A. J. P. Martin, Qualitative analysis of proteins partition chromatographic method using paper , 7. Biochem. 38 224-232 (1944). 

Effect of salt type and concentration The ionic strength of the aqueous solution in eontaet with a reverse micelle phase affects protein partitioning in a number of ways [18,23]. The first is through modification of electrostatic interactions between the protein surface and the surfaetant head groups by modifieation of the eleetrieal double layers adjacent to both the eharged inner mieelle wall and the protein surface. The second effect is to salt out the protein from the mieelle phase because of the inereased propensity of the ionie speeies to migrate to the micelle water pool, reduee the size of the reverse mieelles, and thus displace the protein. 

Selected entries from Methods in Enzymology [vol, page(s)] Computation, 240, 648-649, 652-653 electrostatic potential difference effect on protein partitioning away from isoelectric point,... 

Woll and Hatton [175] have developed a phenomenological thermodynamic model for the partitioning of proteins between aqueous and reverse micellar phases. A simple expression for the protein partition coefficient was derived as a function of pH and surfactant concentration and the partitioning of ribonu-clease A and concanavalin A were shown to correlate well with the model. However, this model was a correlative one but not predictive. 

Protein partitioning and ion co-partitioning in the two-phase system was also modeled by Fraaije et al. [177]. Experiments performed on the partitioning of cytochrome C in TOMAC-octanol-isooctane provided good agreement with the model. At the pH of maximum solubiHzation, no co-partitioning of ions occurred. At pH values below and above the maximum solubiHzation pH, there was exclusion and inclusion, respectively of electrolytes. 

Fletcher PDl, Parrot D (1989) Protein-partitioning between water-in-oil microemulsions and conjugate aqueous phases. In Pileni MP (ed) Structure and reactivity in reverse micelles. Elsevier, Amsterdam, p 303... 

Log ICpgQ is the protein partition coefficient obtained in the PEG-KpHPO -water ATPS. (Wood, P.L., Hawes, D., Janaway, L., Sutherland, LA., /. Liq. Chromatogr. Rel. Technol., 26, 1373-1396,2003.)... 

Typically, in a system such as PEG/dextran or PEG/phosphate, cell debris of a lysed and homogenized fermentation broth will partition to the bottom (dextran or salt) phase whereas the target protein partitions go to the top (PEG) phase. As the partition coefficient often is not much different from 1 (typically between 1 and 5) and PEG would disturb further processing, a second two-phase extraction with the PEG phase, typically with a much lower salt content to salt-in the protein, is necessary to recover the target protein. 

N. L. Abbott, D. Blankschtein, and T. A. Hatton, On protein partitioning in two-phase aqueous polymer systems, Bioseparation 1990, 1, 191-225. 

Goodman, M., and B.W. Barry. 1989. Lipid-protein-partitioning theory (LPP) theory of skin enhancer activity Finite dose technique. Int J Pharm 57 29. 

Williams, A.C., and B.W. Barry. 1991. Terpenes and the lipid-protein-partitioning theory of skin penetration enhancers. Pharm Res 8 17. 

Barry, B.W. 1991. Lipid-protein-partitioning theory of skin penetration enhancement. J Control Release 15 237. 

Tissue blood PCs indicate the relative affinity of compounds for the various tissues of the body compared to blood. The values are determined by the relative lipophilic/hydrophilic nature of the compound and relative affinity for the macromolecules found in tissue and blood. Each individual tissue will make up a specific balance of water, neutral lipid, phospholipid, and protein. Partitioning therefore is determined by the relative affinity of the compound for the specific tissue constituents. 

Many current protein separation operations involve exposure of a protein to interfaces, sometimes as the primary purpose of the process step and sometimes as a secondary consequence of that step. In either case, the extent to which a protein partitions between bulk solution and the interface greatly affects the process, and how multicomponent mixtures partition is even more important and even less understood and less predictable. Protein transport processes are also significant and not well understood, especially in confined or highly concentrated domains such as interstices in porous media and faces of membranes. 

The results of surfactant-dependency on protein trahsfer indicate that protein extraction reverse micelles not only provide a hydrophilic droplet in a non-aqueous solvent to facilitate protein partition, but also make proteins sufficiently hydrophobic to solubilize into an organic solvent by coating the protein surface. Consequently, we suggest that proteins in the aqueous phase are extracted through the formation of an interfacial complex, a surfactant-coated protein and that the hydrophobic property dominates the extraction efficiency of the proteins, as seen in Figure 14.4. The unsaturated or branched alkyl chain may contribute to the formation of a soluble protein-surfactant complex into a non-aqueous solvent. 

Fletcher, D.I. Parrott, D. Protein partitioning between microemulsion phases and conjugate aqueous phases. In Structure and Reactivity in Reverse Micelles Pileni, M.P., Ed. Elsevier New York, 1988 303-322. 

For the extraction of proteins, aqueous two-phase systems (ATPS) are preferred over organic solvents, which usually denature the proteins and render them biologically inactive. They consist of polyethylene glycol (PEG), and a salt (e.g., potassium phosphate) or dextran in water. At concentrations above a critical value, the mixture separates into two phases—one rich in PEG and the other in dextran or salt. In industrial systems, salts are more commonly used because they are relatively inexpensive as compared to dextran. The MW, charge and surface properties of the protein decide how the protein partitions in the system. The nature of the phase components, the MW of the polymer, and the concentration and type of salt used also affect the distribution. ... 

Goodman M and Barry BW. Lipid-protein-Partitioning Theory (LPP) Theory of Skin Enhancer Activity Finite dose Technique. IntJPharm 1989 57 29-40. 

Woll, J. M. Hatton, A. T. "A simple phenomenological thermodynamic model for protein partitioning in reversed micellar systems Bioprocess Eng. 1989,4, pp 193-199. 

A theoretical treatment of aqueous two-phase extraction at the isoelectric point is presented. We extend the constant pressure solution theory of Hill to the prediction of the chemical potential of a species in a system containing soivent, two polymers and protein. The theory leads to an osmotic virial-type expansion and gives a fundamentai interpretation of the osmotic viriai coefficients in terms of forces between species. The expansion is identical to the Edmunds-Ogston-type expression oniy when certain assumptions are made — one of which is that the solvent is non-interacting. The coefficients are calculated using simple excluded volume models for polymer-protein interactions and are then inserted into the expansion to predict isoelectric partition coefficients. The results are compared with trends observed experimentally for protein partition coefficients as functions of protein and polymer molecular weights. 

In this paper we report preliminary work aimed at developing a comprehensive theory of protein partitioning. We focus attention on isoelectric partitioning and use statistical mechanics to examine the fundamental basis of the so called Edmonds-Ogston expression (3) and its extension to four component systems by King et ah (4). This expression,... 

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