Abstract: By mixing bone morphogenetic factor human MP52 with mannitol at a weight ratio of 1:5-50, followed by lyophilization, a stable lyophilized composition of bone morphogenetic factor human MP52 is obtained which prevents coloring and atrophy of the lyophilized product of bone morphogenetic factor human MP52 during storage and also prevents cohesion at the time of reconstitution.

Abstract: A protein having amino acid sequence in SEQ ID No.: 1 of the Sequence Listing derived from human MP52, and a dimer protein thereof. A homodimer protein described above can be obtained by constructing a plasmid containing DNA coding amino acid sequence in SEQ ID No.: 1 of the Sequence Listing with a methionine at the N-terminus, introducing the plasmid into E. coli for transformation, solubilizing inclusion bodies obtained by culturing the transformant, purifying the monomer protein from the solubilized solution, refolding the monomer protein into a dimer protein and purifying the same.