Partition of Proteins in Two‐Phase Systems Containing Charged Poly(ethylene glycol)

Abstract

Proteins havc been partitioned in dextran-poly(cthy1ene glycol) -water biphasic systems containing positively charged poly(ethy1ene glycol). The effect of pH, buffer concentration, polymer concentration, protein concentration and temperature on the partition has been investigated. Characteristic extraction profiles are obtained when the percentage of protein in the upper phase is plotted versus pH. By keeping the salt concentration low, very steep extraction profiles can be obtained. Thus, within an interval of one pI3 unit, a protein is transferred from one phase to the other. This pH-interval is located close to the isoelectric point of the protein.The possibility of resolving the components in a natural enzyme mixture, yeast lysate, by counter-current distribution in this type of biphasic system has been investigated. According to activity measurements, several glycolytic enzymes are resolved by this procedure. Good separation is achieved. For some of the enzymes the activity is split into more than one peak in the counter-current distribution.

Freeze-fracture evidence for the isolation of inside-out spinach thylakoid vesicles

“…3447, was obtained from Pharmacia Fine Chemicals AB, Uppsala, Sweden, and polyethylene glycol 4000 from Union Carbide, New York, NY, USA. Trimethylaminopolyethylene glycol 4000 was synthesized according to JOHANSSON et al (8).…”

Enzyme—enzyme complexes between aspartate aminotransferase and malate dehydrogenase from pig heart muscle

“…The biphasic systems were made up of water, dextran, M w = 5 X 10 s (Pharmacia Fine Chemicals, Uppsala, Sweden) and trimethylaminopoly(ethylene glycol), TMA-PEG [7] or carboxymethyl-poly-(ethylene glycol), CM-PEG [8], both with M n = 6000.…”

Partition of trypsin in two‐phase systems containing a diamidino‐α, ω‐diphenylcarbamyl poly (ethylene glycol) as competitive inhibitor of trypsin

“…Partition of macromolecules in this system depends namely on polyelectrolytes and salts concentration [1,2]. Furthermore, when charged poly(ethylene glycol) is added, partition depends also on the pH of the system, and proteins can be extracted according to their isoelectric points [3,4]. Interactions involved in the process of partition are not specific and a mixture of proteins is often obtained in each phase of the system.…”