Cystatin C in milk basic protein (MBP) and its inhibitory effect on bone resorption in vitro.
A cystein protease inhibitor was identified in the basic fraction of bovine milk. We have reported in our previous study that the milk basic protein (MBP) fraction suppressed osteoclast-mediated bone resorption in vitro. Since osteoclasts secreted cystein protease to digest collagen in the bone matrix, we identified the cystein protease inhibitor in MBP. A 12-kDa inhibitor was purified from MBP by papain affinity gel chromatography and subsequent Hi-Load Superdex 75 gel filtration chromatography. The N-terminal sequence of the 18 amino acid residues of the inhibitor corresponded to bovine cystatin C. The 12-kDa cystein protease inhibitor in MBP therefore seemed to be cystatin C. Purified cystatin suppressed bone resorption with the use of isolated osteoclasts in vitro. Cystatin in MBP is suggested as one of the factors inhibiting bone resorption.
Matsuoka
Yasuhiro
Y
Technology and Research Institute, Snow Brand Milk Products Co. Ltd., 1-1-2 Minamidai, Kawagoe, Saitama 350-1165, Japan. matsuokayasuhiro@snowbrand.co.jp
Serizawa
Atsushi
A
Yoshioka
Tomoe
T
Yamamura
Jun-ichi
J
Morita
Yoshikazu
Y
Kawakami
Hiroshi
H
Toba
Yasuhiro
Y
Takada
Yukihiro
Y
Kumegawa
Masayoshi
M
D000595:Amino Acid Sequence; D000818:Animals; D001862:Bone Resorption; D002417:Cattle; D002478:Cells, Cultured; D055316:Cystatin C; D015891:Cystatins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D008892:Milk / Q000737:chemistry*; D010010:Osteoclasts / Q000187:drug effects; D011817:Rabbits; D016415:Sequence Alignment
D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors