Biochemical Analysis of the Proteins Secreted by Schwann Cells and Schwann Cell-Derived Neurotrophic Substances

The dissociated Schwann cells (SCs) taken from the adult rat sciatic nerve undergoing Wallerian degeneration were cultured in serum-free medium. The SCs serum-free conditioned medium (SC-SF-CM) was collected, ultrafiltrated and concentrated. The proteins secreted by SCs in SC-SF-CM ultrafiltrated-concentrated solution were analyzed by SDS-PAGE. It was found that there were 14 protein bands, which molecular weight were from more than 94 KDa to less than 43 KDa, with their main band at 65 KDa. By immunoblotting (Western Blot) for anti-2.5S NGF antibody, NGF was identified to exist in the proteins secreted by SCs. SC-SF-CM ultrafiltrated-concentrated solution was also separated by Disc-PAGE at 4°C, then electroluted, concentrated and collected. By biological activity examination for motor neuro-trophic substances, one protein zone (B+) of these was identified to have motor NTF activity, which contain five protein bands from 65 KDa to 34 KDa.

Serum Protein Zone Electrophoresis—An Outmoded Test?

The predictive value of plasma protein changes in disease is very largely unknown, as relevant clinical and laboratory studies are lacking. The usefulness of zone electrophoresis as a method of detecting a constellation of plasma protein changes is even less clear. With the advent of precise automated techniques for specific plasma protein measurement, zone electrophoresis has little to offer except in the identification and quantitation of paraproteins, where it is essential.

The interaction between α2-macroglobulin and cationic aspartate aminotransferase

On starch-gel or polyacrylamide-gel electrophoresis of human serum, a supernumerary zone of aspartate aminotransferase activity may be demonstrated, migrating with the slow α2 protein zone. This appearance is due only to cationic aspartate aminotransferase, bound by α2-macroglobulin. The binding is strongly potentiated by dilute borate buffers.

PROTEIN SYNTHESIS IN DARK-GROWN BEAN LEAVES

RuDP carboxylase was present in 4-day-old, dark-grown bean leaves. The enzyme increased during subsequent dark growth and in 11 days reached one-third of the specific activity of a light-grown control. Preparative disc electrophoresis of the soluble protein revealed a zone symmetrical with RuDP carboxylase. Increases in RuDP carboxylase during dark growth were matched by corresponding increases in this protein zone. The correlation indicated that the enzyme accounted for 45% of the soluble protein in 11-day-old, light-grown leaves. The formation of peroxidase and catalase was much slower than the formation of RuDP carboxylase during dark growth.

ZONE ELECTROPHORESIS OF THE PROTEINS OF THE FOWL'S SERUM AND EGG YOLK

In addition to the six protein fractions distinguishable in sera from cocks or sexually immature pullets by zone electrophoresis in aqueous veronal, two lipoprotein zones have now been distinguished in sera from laying hens or estrogenized pullets by this same technique. Phosvitin has been detected in serum of estrogenized hens by zone electrophoresis of a saline solution of crude serum lipovitellin obtained from the serum. Six protein zones have been distinguished in similar electropherograms of egg yolk. The six protein zones have been identified provisionally, and in order of decreasing mobility under the conditions used, as phosvitin, α-livetin, β-livetin, γ-livetin, lipoprotein P-1 (possibly a lipovitellenin complex), and lipoprotein P-2 (possibly a lipovitellin complex). Evidence is submitted that the foregoing two major lipoprotein zones from egg yolk are closely similar to, or identical with, the two lipoprotein zones from sera of laying hens or estrogenized pullets. The status of a seventh minor protein zone in electropherograms of yolk protein is uncertain.