Electrophoretic patterns of serum albumins collected from hereditary obese and diabetic mice.

Sera collected at different post-feeding times from C57BL/6J, C57BL/6J-ob/ob, C57BL/KsJ and C57BL/Ksj-db/db mice were electrophoresed in urea-containing gels. According to variation in susceptibility of albumin molecules to urea denaturation, several ligand-binding albumins migrated as different bands. Sera collected at different post-feeding times from C57BL/6J mice showed different electrophoretic patterns; serum collected after a 20-hr starvation period consisted mainly of fatty acid-bound albumin (Band 1); serum collected after refeeding lacked fatty acid-bound albumin but contained slower migrating bands (Bands 3-7, the nature of which are obscure and show a resemblance to normal human sera. Sera collected during and after feeding from C57BL/6J-ob/ob mice showed an albumin pattern resembling that collected during and after feeding from C57BL/6J normal mice, but that collected during the fasting state from ob/ob mice contains Bands 3-7, which were not observed in the fasting state in normal mice. On the contrary, sera collected from C57BL/KsJ-db/db mice showed quite different patterns; Bands 3-4 did not appear in the sera collected during and after feeding, although the albumin pattern in the fasting state showed a normal pattern. Administration of insulin or anti-diabetic agents to fasted mice induced Bands 3-7, suggesting a relationship of Bands 3-7 to glucose metabolism of insulin action. To study the nature of the albumin-ligand complex, in vitro experiments were conducted and are reported herein.