Polyethylene Glycol Compounds Research Articles

Factors affecting cardiolipin antibody assays: modification with polyethylene glycol compound.

Anti-cardiolipin antibody (aCL) measurement is only semi-reproducible, and current assays detect irrelevant as well as clinically significant antibodies. Factors found to influence results included the source of the enzyme-linked immunoabsorbent assay (ELISA) plate, and its pretreatment with solvents; the nature of the blocking solution; and the composition of the diluent used for reagents. Fetal calf serum (FCS) in the diluent appeared to reduce nonspecific (clinically irrelevant) binding and was not simply a source of beta2-glycoprotein-1 (beta2GP1). A polyethylene glycol compound was found to be an effective blocking agent, and its use enhanced the discrimination between positive and negative samples. A high level of variation may be inherent in aCL-ELISA methodology, but the use of polyethylene glycol compound appeared to be a helpful modification.

Stabilization of Escherichia coli penicillin G acylase by polyethylene glycols against thermal inactivation.

The effects of five polyethylene glycol (PEG) compounds of different molecular weight on the thermal stability of penicillin G acylase (PGA) obtained from a mutant of Escherichia coli ATCC 11105 have been investigated. The molecular weights of PEG compounds were 400, 4000, 6000, 10,000, and 15,000. The thermal inactivation mechanisms of both native and PEG-containing PGA were considered to obey first order inactivation kinetics during prolonged heart treatments. Optimal concentrations of PEGs at molecular weights of 400, 4000, 6000, 10,000, and 15,000 were found to be 250, 150, 150, 100, and 50 mM, respectively. The greatest enhancement of thermostability was observed with PEG 4000 and PEG 6000, as a nearly 20-fold increase above 50 degrees C. PGA showed almost the same temperature activity profile and optimal temperature values both in the presence and absence of PEG. The addition of PEGs did not cause any change in the optimal temperature value of PGA, but the parameters Vm, K(m), the activation energy, and the Kcat values of enzyme were markedly decreased because of the mixed inhibition by PEG compounds. The type of inhibition was found to be hyperbolic uncompetitive.

A two-phase polymer method for isolation of maturing goat sperm plasma membrane.

An aqueous two-phase polymer method originally developed for the isolation of plasma membrane from mature goat epididymal spermatozoa (Rana, A.P.S. and Majumder, G.C., Prep. Biochem., 17, 261, 1987) has been found to be unsuitable for the maturing spermatozoa derived from caput and corpus epididymides because of significant contamination of the isolated membrane with intact cells. A modified method has been developed by manipulating the centrifugal force (required for membrane sedimentation) for the isolation of maturing sperm plasma membrane of high yield (approximately 55%) and purity as judged by marker enzyme assays and phase contrast and electron microscopic analyses. The method consists of treatment of intact spermatozoa with 1.25 mM EDTA, dispersion of these cells to a two-phase polymer system comprising 5.5% 252-Kd dextran and 4.2% 20-Kd polyethylene glycol compound and subsequent centrifugation at 12,000 X g for 30 min when the two phases separate out and membranes sediment at the interphase. The repeatation of the two-phase fractionation step yielded greater purity of the plasma membrane.

Thin sections of clay and shale

Clay and shale samples can be impregnated while retaining their natural moisture. Carbowax 6000 (Carbide and Carbon Chemical Co.), a waxlike high molecular weight polyethylene glycol compound was used. This wax is not isotropic and reacts with some clay minerals. After impregnation the samples can be cut and thin sectioned using kerosene instead of water. The kerosene is removed before the slice is mounted on a glass slide. Samples required for sectioning should be collected moist in the field and well wrapped immediately in aluminum foil to prevent their drying out.