Proteolytic activation and inactivation of the serine protease activity of plasma hyaluronan binding protein.
We prepared anti-plasma hyaluronan binding protein (PHBP) mouse monoclonal antibodies and studied the fragmentation profile of PHBP with them. PHBP is present in human plasma as a single polypeptide chain (70 kDa). During the purification, PHBP partially fragmentated into the 50-kDa N-terminal fragment and the 27-kDa C-terminal fragment. After the incubation of the purified PHBP, the 70-kDa precursor form was completely cleaved to the 50- and 27-kDa fragments, followed by the 50-kDa to the 26-kDa, and the 27-kDa to the 17-kDa plus the 8-kDa fragments, respectively. Because the purified PHBP contained no other detectable proteins and PHBP has a typical serine protease domain, we concluded that the fragmentation of PHBP was caused by own serine protease activity. PHBP cleaved the C-terminal side of Arg in the peptide effectively and that of Lys weakly. The results of the pre-incubation experiments of PHBP suggested that the single-chain form of PHBP is a precursor, the two-subunit structure is an active form and the three- or four-chain structure is an inactive form of a serine protease.
Choi-Miura
N H
NH
Department of Physiological Chemistry, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan. nammiura@pharm.showa-u.ac.jp
Takahashi
K
K
Yoda
M
M
Saito
K
K
Mazda
T
T
Tomita
M
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D018960:Hyaluronan Receptors; D011480:Protease Inhibitors; D012697:Serine Endopeptidases