Isolation of tyrosine-melanocyte-stimulating hormone release-inhibiting factor 1 from bovine brain tissue.

Although Tyr-melanocyte-stimulating hormone release-inhibiting factor 1 (MIF-1) (Tyr-Pro-Leu-Gly-NH2) can exert a number of biological actions in the brain and elsewhere, it has never been isolated from any tissue. Accordingly, we attempted to purify it from acetic acid extracts of bovine brain tissue by gel filtration chromatography and several different high performance liquid chromatographic systems. Peptide content was followed by a specific and sensitive radioimmunoassay with an antibody that was generated against synthetic Tyr-MIF-1. In each of the five applied high performance liquid chromatographic systems, the immunoreactive fractions coincided exactly with the elution time of synthetic Tyr-MIF-1 in the control runnings. The structure of the isolated peptide was identified by microsequence analysis as the tetrapeptide Tyr-Pro-Leu-Gly-NH2 and shown to be biologically active.