Biomaterial Database

Mechanism of poly(ethylene glycol) interaction with proteins. 1985

T Arakawa, and S N Timasheff

Poly(ethylene glycol) (PEG) is one of the most useful protein salting-out agents. In this study, it has been shown that the salting-out effectiveness of PEG can be explained by the large unfavorable free energy of its interaction with proteins. Preferential interaction measurements of beta-lactoglobulin with poly(ethylene glycols) with molecular weights between 200 and 1000 showed preferential hydration of the protein for those with Mr greater than or equal to 400, the degree of hydration increasing with the increase in poly(ethylene glycol) molecular weight. The preferential interaction parameter had a strong cosolvent concentration dependence, with poly(ethylene glycol) 1000 having the sharpest decrease with an increase in concentration. The preferential hydration extrapolated to zero cosolvent concentration increased almost linearly with increasing size of the additive, suggesting steric exclusion as the major factor responsible for the preferential hydration. The poly(ethylene glycol) concentration dependence of the preferential interactions could be explained in terms of the nonideality of poly(ethylene glycol) solutions. All the poly(ethylene glycols) studied, when used at levels of 10-30%, decreased the thermal stability of beta-lactoglobulin, suggesting that caution must be exercised in the use of this additive at extreme conditions such as high temperature.

UI	MeSH Term	Description	Entries
D007782	Lactoglobulins	Globulins of milk obtained from the WHEY.	Lactoglobulin,beta-Lactoglobulin,beta-Lactoglobulin A,beta-Lactoglobulin B,beta-Lactoglobulin C,beta-Lactoglobulin E,beta-Lactoglobulin F,beta-Lactoglobulin G,beta-Lactoglobulin I,beta Lactoglobulin,beta Lactoglobulin A,beta Lactoglobulin B,beta Lactoglobulin C,beta Lactoglobulin E,beta Lactoglobulin F,beta Lactoglobulin G,beta Lactoglobulin I
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D011092	Polyethylene Glycols	Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.	Macrogols,Polyoxyethylenes,Carbowax,Macrogol,Polyethylene Glycol,Polyethylene Oxide,Polyethyleneoxide,Polyglycol,Glycol, Polyethylene,Glycols, Polyethylene,Oxide, Polyethylene,Oxides, Polyethylene,Polyethylene Oxides,Polyethyleneoxides,Polyglycols,Polyoxyethylene
D011489	Protein Denaturation	Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.	Denaturation, Protein,Denaturations, Protein,Protein Denaturations
D011506	Proteins	Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D006146	Guanidines	A family of iminourea derivatives. The parent compound has been isolated from mushrooms, corn germ, rice hulls, mussels, earthworms, and turnip juice. Derivatives may have antiviral and antifungal properties.
D012259	Ribonuclease, Pancreatic	An enzyme that catalyzes the endonucleolytic cleavage of pancreatic ribonucleic acids to 3'-phosphomono- and oligonucleotides ending in cytidylic or uridylic acids with 2',3'-cyclic phosphate intermediates. EC 3.1.27.5.	RNase A,Ribonuclease A,Pancreatic RNase,RNase I,Ribonuclease (Pancreatic),Ribonuclease I,Pancreatic Ribonuclease,RNase, Pancreatic
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic
D019791	Guanidine	A strong organic base existing primarily as guanidium ions at physiological pH. It is found in the urine as a normal product of protein metabolism. It is also used in laboratory research as a protein denaturant. (From Martindale, the Extra Pharmacopoeia, 30th ed and Merck Index, 12th ed) It is also used in the treatment of myasthenia and as a fluorescent probe in HPLC.	Guanidine Hydrochloride,Guanidinium,Guanidinium Chloride,Guanidine Monohydrate,Guanidine Monohydrobromide,Guanidine Monohydrochloride,Guanidine Monohydroiodine,Guanidine Nitrate,Guanidine Phosphate,Guanidine Sulfate,Guanidine Sulfate (1:1),Guanidine Sulfate (2:1),Guanidine Sulfite (1:1),Guanidium Chloride,Chloride, Guanidinium,Chloride, Guanidium,Hydrochloride, Guanidine,Monohydrate, Guanidine,Monohydrobromide, Guanidine,Monohydrochloride, Guanidine,Monohydroiodine, Guanidine,Nitrate, Guanidine,Phosphate, Guanidine,Sulfate, Guanidine