Purification of macrophage migration inhibitory factor (MIF) from bovine brain cytosol.

Two isoforms of the macrophage migration inhibitory factor (MIF) have been isolated to homogeneity from bovine brain cytosol. In agreement with the cDNA sequence of their human counterpart, they both have an apparent molecular weight of 12 kDa and are characterized by the following N-terminal amino acid sequence NH2-PMFVVNTNVPRASVPDGLLSELTQQLAQATGKPPQYIAV-. CD spectra revealed that bovine MIF contains 42% (+/- 3%) alpha-helix and 21% (+/- 3%) beta-structure. CD-constrained prediction of the secondary structure assigned MIF to the alpha/beta-class of proteins.