A double-label two-dimensional gel electrophoresis procedure specifically designed for serum or plasma protein analysis

Differential effects of methylmercury on the synthesis of protein species in dorsal root ganglia of the rat

Dorsal root ganglia from control and methylmercury (MeHg)-treated rats were incubated in vitro with 35S-methionine ant the proteins synthesized were analyzed by two-dimensional electrophoresis. The double labelling method, in which proteins of control dorsal root ganglia labelled in vitro with 3H-leucine were added to each of the two samples as an internal standard, was used to minimize unavoidable errors arising from the resolving procedure itself. The results obtained showed that the effect of MeHg on the synthesis of proteins in dorsal root ganglia was not uniform for individual protein species in the latent period of MeHg intoxication. Among 200 protein species investigated, 157 showed inhibition of synthesis close to that of the total proteins in the tissue (68% of the control). Among the remaining protein species, 20 showed real stimulation of synthesis, whereas 7 were moderately inhibited and 16 were inhibited more strongly than the total proteins in the tissue. These results suggest that the effect of MeHg on the synthetic rates for protein species in dorsal root ganglia differs with the species, and that unusual elevation or reduction of the synthesis of some protein species caused by MeHg may lead to impairment of normal nerve functions.

A search for protein abnormalities in erythrocyte membranes and platelets from patients with multiple sclerosis using double-label two-dimensional electrophoresis

Proteins from erythrocyte membranes and whole platelets from patients with definite multiple sclerosis (MS) and normal subjects were compared using a double-label two-dimensional procedure. No consistent differences were found in the proteins adherent or intrinsic to erythrocyte membranes. The results of initial studies with platelets showed the absence of a group of three protein spots in the electrophoretic gels of the MS specimens. Further experiments suggested that these results were probably due to minor differences in the handling of the MS and normal specimens although the possibility of a difference in protease activity was not completely eliminated.

Visualization of multiple protein bands on the same nitrocellulose membrane by double immunoblotting

A method has been developed which allows the simultaneous immunodetection of more than one type of protein on the same nitrocellulose membrane. This procedure does not require special labeling of samples or elution of antibodies from the membrane as do the alternatives cited in the literature (1,2). Proteins are separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to the membrane before specific immunostaining with either peroxidase/4-chloro-1-naphthol or immunogold/silver staining. Antigen identity is visually determined by the formation of different-colored precipitates on the membrane. This innovation in protein blotting offers a savings in time and reagents as well as permitting identification of closely spaced bands with certainty.

A double-label two-dimensional procedure for the analysis of membrane proteins

A previously described double-label two-dimensional electrophoresis procedure (Wheeler et al., Anal. Biochem. 1986 159, 1-7) for the analysis of differences between two complex mixtures of soluble proteins has been modified to allow analysis of proteins requiring detergent for aqueous solubility. The samples are first disrupted by sonication and the insoluble proteins concentrated by high-speed centrifugation. The proteins are then solubilized with sodium dodecyl sulfate and further concentrated in a centrifugal concentrator to achieve protein mixtures suitable for labeling with 14C and 3H by reductive methylation and subsequent two-dimensional electrophoresis. The sample concentration step is quick, minimizes the concentration of sodium dodecyl sulfate in the final sample, and avoids the potential difficulties associated with lyophilization or precipitation. The modified procedure was applied to the analysis of erythrocyte membranes, platelets and isolated placental microvilli. The high resolving power of two-dimensional gel electrophoresis is retained and the procedure is sensitive because the conditions of labeling allow substantial incorporation of radioactivity into protein despite the presence of detergent.

Search for abnormal proteins in erythrocytes and plasma from patients with a major depressive episode

A sensitive double-label two dimensional gel electrophoresis procedure has been used to search for abnormal proteins in plasma and erythrocyte plasma membranes from patients with major depressive illness. For both plasma and erythrocytes, minor qualitative and quantitative differences between the proteins in pooled samples from depressed and normal subjects were observed; however, these were shown to be artifacts and no consistent differences were found.

Double-label two-dimensional electrophoresis of serum and plasma proteins from patients with multiple sclerosis

A double-label two-dimensional electrophoretic procedure has been used to search for abnormal proteins in the serum and plasma of patients with definite multiple sclerosis. The procedure possesses high resolving power and is particularly valuable in comparative studies of complex mixtures of proteins since differences due to gel-to-gel variations in protein mobilities are eliminated. Proteins present in serum and plasma at a concentration of 5-10 micrograms/ml are detected routinely. No consistent differences were observed between patients with multiple sclerosis and normal subjects in comparisons using pooled or individual specimens of serum or plasma. The absence of consistent differences in serum and plasma proteins between normal subjects and MS patients applied even when the sensitivity of the procedure was increased several-fold and when the possibly obscuring effect of albumin in the electrophoretic gels was eliminated. To our knowledge, this study combines the most extensive and sensitive search for consistent abnormalities in serum and plasma proteins in multiple sclerosis sera thus far reported.