Youji Shimazaki

Determination of Malic Acid Using a Malate Dehydrogenase Reactor After Purification and Immobilization in Non-Denaturing Conditions and Staining with Ponceau S

Mouse liver cytosolic malate dehydrogenase was separated by non-denaturing two-dimensional electrophoresis and identified. Furthermore, the activity of the enzyme was preserved even after separation, electroblotting onto a membrane and staining with Ponceau S in acidic buffer solution (pH 5.1). Using the membrane-immobilized enzyme, the malic acid content was estimated by measuring absorbance changes due to the conversion of nicotinamide adenine dinucleotide (NAD) to NADH. These results indicate that enzyme reactors can be systematically produced after purification, immobilization and staining with Ponceau S.

Production of immunoaffinity membranes for direct analysis of antigen after antibody separation and blotting under non-denaturing conditions

Membrane-immobilized anti-transferrin antibody, which was produced after antibody was separated using non-denaturing two-dimensional electrophoresis (2DE), was transferred to a polyvinylidene difluoride (PVDF) membrane and was stained by direct blue 71. The antigen, transferrin, specifically bound to the membrane-immobilized antibody and was eluted only after rinsing the membrane with glutamic acid or aspartic acid solution. The antigen was analyzed directly by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) when the membrane was incubated with human plasma after the removal of human serum albumin using polyethylene glycol. The transferrin extracted by glutamic acid or aspartic acid solution retained the binding of Fe3+ in the presence of the carbonate anion. We found that immunoaffinity membranes can be useful for simple and rapid removal and extraction of intact proteins after antibody separation and blotting under non-denaturing conditions.

Simultaneous production of immunoaffinity membranes

We simultaneously separated antibodies for transferrin, the third component of complement (C3), haptoglobin and transthyretin by multi-sample non-denaturing two-dimensional electrophoresis (2-DE), transferred them to a polyvinylidene difluoride (PVDF) membrane and then stained them using direct blue 71 to obtain membrane-immobilized antibodies. The antigens, transferrin, C3, haptoglobin and transthyretin were specifically bound to the membrane-immobilized antibodies and were eluted only after rinsing the membrane with acid solution. The antigens specifically bound to the membrane-immobilized antibodies were separated by SDS-PAGE and identified by peptide mass fingerprinting using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Furthermore, transferrin and transthyretin were trapped and eluted by each membrane-immobilized antibody and detected by MALDI-TOF MS directly without separations. Using membrane-immobilized anti-transferrin antibody, transferrin in flowing blood was directly trapped and analyzed. The results indicated that membrane-immobilized antibodies are simultaneously produced, and that the immunoaffinity membranes can capture specific substances in flowing fluids.

Successive analysis of antigen trapping and enzymatic digestion on membrane-immobilized avidin

Avidin from egg white was migrated toward a cathode of nondenaturing electrophoresis and then immobilized on a polyvinylidene difluoride membrane. Adrenocorticotropic hormone (ACTH) was specifically captured after the biotinylated anti-ACTH antibody was bound to the membrane-immobilized avidin, and the captured ACTH was digested by the biotinylated trypsin on the membrane after extraction. The digested polypeptides from the ACTH were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). These results indicate that target substances can be specifically trapped and digested on membrane-immobilized avidin.

Silver staining of an esterase compatible with activity and mass spectrometry analysis after separation using non-denaturing two-dimensional electrophoresis.

BACKGROUND Enzyme activity is normally lost when formaldehyde is used as a reductant for silver staining after separation by electrophoresis. Hydrolytic activity of esterases can be examined on membranes without impairing enzyme activity when another reductant such as glucose is used for silver staining of the enzyme after separation by non-denaturing two-dimensional electrophoresis (2-DE) and subsequent transfer. METHODS The hydrolysis of lipids in human high density lipoprotein (HDL) by esterases first separated on a polyvinylidene fluoride membrane using non-denaturing 2-DE and silver stained using glucose as a reductant was examined. RESULTS Esterase activity was retained after glucose was used as a silver reductant for silver staining after separation using non-denaturing 2-DE. Lipids of HDL were removed by the esterases retained on the membrane after esterases were separated by 2-DE. CONCLUSION The results indicated that hydrolytic enzyme activity is retained after separation, staining and immobilization.

Removal of specific protein spots on the patterns of non-denaturing two-dimensional electrophoresis using protein A agarose and antibodies

Protein spots, such as immunoglobulin G (IgG), A (IgA) or alpha 2-macroglobulin, on the patterns of non-denaturing two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) were selectively removed by the application of protein A or antibody-conjugated protein A agarose to the first-dimension gel top at the cathode side. A protein residing at pI 5.8 and with a molecular mass of about 200 kDa was clearly detected when the IgG and IgA spots were removed from the 2-D PAGE pattern.

Epitope analysis using membrane-immobilized avidin and protein A

Adrenocorticotropic hormone (ACTH) and transferrin were trapped by biotinylated anti-ACTH antibody and anti-transferrin antibody, respectively, bound to membrane-immobilized avidin. Polypeptides with the sequences SYSMEHFR, SYSMEHFRWGKPVGK and SYSMEHFRWGKPVGKK were bound to the biotinylated anti-ACTH antibody on the membrane-immobilized avidin after the trapped ACTH was digested with trypsin on the membrane and non-binding polypeptides were washed from the membrane. Further, the polypeptides with the sequence SYSMEHFRWGKPVGK and SYSMEHFRWGKPVGKK were trapped by anti-ACTH antibody bound to membrane-immobilized protein A. The antibody recognized the WGKPVGK region of the antigen, ACTH. Polypeptide with the sequence SMGGKEDLIWELLNQAQEHFGKDK was bound to the biotinylated anti-transferrin antibody on the membrane-immobilized avidin after the trapped transferrin was digested with trypsin on the membrane and non-binding polypeptides were washed from the membrane. Further, the polypeptide with the sequence SMGGKEDLIWELLNQAQEHFGKDK was trapped by anti-transferrin antibody bound to membrane-immobilized protein A. The antibody recognized the SMGGKEDLIWELLNQAQEHFGKDK region of the antigen, transferrin. These results thus indicate that the combined methods of membrane-immobilized avidin and protein A can be applied to examine the epitopes of antigens.

Simple quantification of Cu,Zn-superoxide dismutase activity after separation by non-denaturing isoelectric focusing

The Cu,Zn-superoxide dismutase (SOD) activity in bovine retina cytosol was separated from retinal pigment using short-length non-denaturing isoelectric focusing (IEF) (15-mm long x 1.3-mm i.d. column) and detected using non-denaturing two-dimensional electrophoresis (2-DE). After the SOD and pigment in the retina cytosol are separated, SOD activity can be quantified by water-soluble tetrazolium salt. We also found that SOD separated by this IEF retained its native function.

Reversible Inhibition of Esterase Activity After Separation and Immobilization

An inhibitor, 9-amino-1,2,3,4-tetra hydroacridine (tacrine), is a reversible inhibitor of esterases. The reversible inhibition of the enzyme activity is thought to be examined after separation and immobilization of the enzyme under non-denaturing conditions. Hydrolytic changes of phosphatidylcholine by carboxylesterase were obtained using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry after the esterase was separated by non-denaturing two-dimensional electrophoresis, was immobilized to membranes and was stained by Ponceau S. The changes were inhibited after the enzyme on the membrane was treated by tacrine. Furthermore, the hydrolytic activity of the esterase was recovered after the inhibitor was washed with aspartic acid solution. These results indicate that the phosphatidylcholine hydrolysis activity of the isolated and immobilized enzyme is reversibly inhibited under non-denaturing conditions. Furthermore, this method can be developed to the production of an enzyme reactor able to regulate amounts of lipids.

Production of enzyme reactors after separation by non-denaturing two-dimensional electrophoresis and immobilization on membrane

Activities of carboxylesterase and malate dehydrogenase on membranes were retained after enzymes of mouse liver cytosol were separated by non-denaturing, two-dimensional electrophoresis (2-DE), stained using imidazole and zinc salts and electroblotted on to membranes. Furthermore, hydrolytic changes of phosphatidylcholine by the esterase were examined using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) after separation, and reversible staining and immobilization to membranes. Hydrolytic activity of the esterase on the membranes was 20% of the original activity of the tissue homogenate. The present method can be applied to the production of several types of enzyme reactors on membranes.