The structure and physicochemical properties of rat liver macrophage migration inhibitory factor.
We expressed rat macrophage migration inhibitory factor (rMIF) in E. coli using the cDNA isolated from a rat liver cDNA library. rMIF specifically bound glutathione (dissociation constant = 500 microM). We purified rMIF homogeneously on SDS-PAGE by S-hexylglutathione Sepharose affinity column chromatography and Sephadex G-100 column chromatography. The amino-acid sequence of rMIF was highly homologous to that of human MIF from a T-cell line; only a single amino-acid residue was substituted if conservative amino-acid substitutions were involved. The molecular weight of rMIF was calculated to be 12.4 kDa and 23.6 kDa by SDS-PAGE and analytical ultracentrifugation, respectively. Thus, it was concluded that the native rMIF formed a homodimeric structure. Proton nuclear magnetic resonance (1H-NMR) study revealed that rMIF was less thermostable (the denaturing temperature was from 50-60 degrees C) than human MIF (the denaturing temperature is about 80 degrees C (Nishihira et al. (1993) Biochem. Mol. Biol. Int. 31, 841-850). The secondary structure of rMIF evaluated by 1H-NMR experiments revealed that the contents of alpha-helix, beta-strand, and coil were 13.8%, 55.6%, and 30.6%, respectively.
Nishihira
J
J
Central Research Institute, School of Medicine, Hokkaido University, Sapporo, Japan.
Kuriyama
T
T
Sakai
M
M
Nishi
S
S
Ohki
S
S
Hikichi
K
K
D000818:Animals; D004926:Escherichia coli / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008263:Macrophage Migration-Inhibitory Factors / Q000096:biosynthesis / Q000302:isolation & purification*; D008264:Macrophages / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D017433:Protein Structure, Secondary; D051381:Rats; D014461:Ultracentrifugation
D008263:Macrophage Migration-Inhibitory Factors