Continuous gradient polyacrylamide microgel electrophoresis is one of the methods for examining a minute amount of sample. We applied this method for the investigation of proteins of cerebrospinal fluid (CSF) in normal subjects and patients suffering from neurological diseases. We could analyse the proteins of unconcentrated CSF in amount of under 1μl. The amount of albumin was calculated directly from the area under the albumin peak on the densitogram with the standard line of albumin. Twelve bands of proteins were obvious and they always appeared at the same positions on the gel in all normal CSF samples. Proteins more anodic than albumin were clearly analysed in this method as well as those more cathodic than albumin. We examined the relationship between various neurological diseases and the amount of the protein which was located at the most anodic side (band 1).

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A new method for the discrimination of epitopes of monoclonal antibodies by biotin-avidin enzymeimmunoassay was developed. The principle of this method was as follows: Several monoclonal antibodies reacted with one antigen were defined. After incubation of one non-biotinylated monoclonal antibody in the antigen coated polystylene plate, biotinylated another monoclonal antibody was added and incubated. After washing, peroxidase conjugated avidin was reacted. Finally, peroxidase activity was assayed using O-phenylenediamine as substrate containing H₂O₂. As the results, it was probable that the non-biotinylated monoclonal antibody was different from the biotinylated monoclonal antibody when peroxidase activity could be detected. On the other hand, it was suggested that the non-biotinylated antibody had a same epitope of the biotinylated antibody, or the antigenic determinants which were recognized with both monoclonal antibodies were very closed when peroxidase activity couldn't be detected.
This method was very easy and safe to handle comparing with the method using radioactive compounds. The biotinylated antibodies, furthermore, were stable over one year when they were stocked at 4°C.

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The present study was performed to evaluate the changes of the composition of urinary protein during normal pregnancy.
In fifteen normal pregnancies, the composition of urinary protein was analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE).
In electrophoretic pattern of urinary protein, one or two bands (Molecular weight: 71×10³ and 94×10³) were observed during the first trimester and number of bands increased to seven during the third trimester, but decreased to two at one month after delivery.
We concluded that the SDS-PAGE appeared useful in assessing the urinary protein in pregnancy.

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Biochemical properties of LDH linked immunoglobulin complexes found in sera of three cases (IgG-κ, IgA-κ, IgG-κ, λ) were studied. The complexes were completely dissociated by gel filtration at pH 3.0 and the dissociated LDH with normal molecular size showed a normal zymogram. When the dissociated immunoglobulins were incubated with each of the LDH isozymes (LDH_1-5), the two IgG type immunoglobulins recombined with all isozymes, but the IgA type immnoglobulin showed limited combination with only LDH_{2, 3, 4} fractions, indicating a difference in binding specificity between IgG and IgA.
Subclass specificity tested in two IgG types was not detected by Protein A affinity chromatography. The binding site of IgG was confirmed to exist on the Fab portion by the method of papain digestion. 5'-AMP-Sepharose 4 B affinity chromatography revealed different affinity between LDH linked IgG (broad pattern) and LDH linked IgA (extra band). This finding suggests the presence of conformational heterogeneity.

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The microhetrogeneity of human transferrin were examined by isoelectric focusing with modified immobilized pH gradient.
Purified human diferric transferrin were separated to four bands (A: pI 5.15∼5.19, B: pI 5.26∼5.30, C: pI 5.37∼5.42, D: pI 5.50∼5.54) on immobilized gradient gel. The statement of equality between four transferrins ratios is a proportion A:B:C:D=1:3:5:1. No significant difference between the binding of each transferrin fractions to cell surface receptor was obserbed. The presence of A, B, C and D transferrin fraction in native normal serum was detected by immunofixiation test.

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Superoxide dismutase (SOD) was isolated and partially purified from pooled mouse erythrocytes by treating with organic solvents followed by gel filtration and ion-exchange chromatography. The purified SOD showed two major and three minor bands on polyacrylamide gel electrophoresis. All these bands were proven to be cuprozinc SOD (Cu, Zn-SOD) by the KCN inhibition test. The Cu, Zn-SOD was a dimer with a molecular weight of 32, 000 daltons consisting of two subunits, each of which with a molecular weight of 16, 000 daltons. Ultraviolet absorption spectrum and PAS staining patterns of the Cu, Zn-SOD indicated that the enzyme contains very low levels of both tyrosine and tryptophan residues and carbohydrates. Lyophilization of the purified enzyme induced an SOD-active, slow moving extraband on polyacrylamide gel electrophoresis, possibly as a result of aggregation during lyophilization.

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