Further studies on the electrophoretic pattern of albumin in diabetic sera

Human sera from normal subjects and diabetic patients were electrophoresed in an urea-containing gel; polyacrylamide gel and cellulose acetate membrane. In polyacrylamide gel, normal serum exhibited the fast migrating Band 2 and the slower migrating albumin Bands 4 and 5 after overnight fasting and also after glucose administration. In diabetic serum Bands 4 and 5 did not appear before or after glucose administration in low mercaptoethanol gel which abnormality resembled the pattern in C57BL/KsJ-db/db mice. In high mercaptoethanol gel, about half of the diabetic sera exhibit a delay in appearance of Bands 4 and 5, i.e., Bands 4 and 5 were not observed 30--60 min after glucose administration, which seems to resemble the pattern in C57BL/6J-ob/ob mice. Conditions of electrophoresis in urea-submerged cellulose acetate membrane (species of buffer systems, pH, ion concentration, mercaptoethanol, ethylene-diaminetetraacetic acid, Ca2+ ion, urea concentration, etc.) were observed in relation to albumin sub-separation. At pH 8.6 with barbital buffer, albumin separated into two bands, and at pH 10.6 with glycine buffer, albumin separated into four bands. Almost all diabetic sera (ca. 80%) exhibited different electrophoretic patterns from that of normal serum.