Three-dimensional Models of Four Mouse Mast Cell Chymases (1)
Seven different 26-32-kDa mast cell serineproteases,designated mouse mast cell protease(mMCP) 1 to mMCP-7, have been identified in the granules of mouse mast cells.
mMCP-1 and mMCP-2 are preferentially expressed in mucosal mast cells, a subclass of mast cells that increases in the intestines of helminth-infected BALB/c mice. In contrast, mMCP-4, mMCP-5, and mMCP-6 are preferentially expressed in the mouse mast cells that reside in the serosal cavity of BALB/c mice.
The amino acid sequence alignment of mMCP-1m, MCP-2, mMCP-4, mMCP-5,and rMCP-II with pancreatic chymo-trypsin is shown.
When the 3D models of mMCP-1, mMCP-2, mMCP-4, and mMCP-5 were calculated, their backbones were found to be virtually indistinguishable from the backbone of rMCP-II. The nine segments that are predicted to be the best for obtaining protease-specific anti-peptide immunoglobulins are shown. The two most favored segments, according to the four criteria used, correspond to residues 74-89 (87-102)(segment 3 )and 196- 207 (212-224) (segment 9). Both segments are protruding reverse turns.
The nine segments that are predicted to be the best for obtaining protease-specific anti-peptide immunoglobulins are shown. The two most favored segments, according to the four criteria used, correspond to residues 74-89 (87-102) (segment3) and 196-207(212-224)(segment 9). Both segments are protruding reverse turns.
Proteoglycan Binding Regions in mMCP-4 and rnMCP-5 are located at opposite ends of the molecule. The regions are in separate domains and are equidistant from the active site at the interface between the two domains of the protein. The two positively charged regions are convex stripsapproximately 20A long and 10A wide. Region 1 consists of Arg-12(27), two antiparallel strands(120-125 (133-138),145-149 (159-163)),and tips of two loops (169-175(184-188), 200-205(217-224)). Region 2 consists saturn (35-39(47-51), two anti-parallel strands (69-75(82-88), 93-100(106 113)), and two turns of the COOH-terminal a-helix (220- 226 (239-245).
Region 1 has a net charge of +10 in mMCP-4 and +9 in mMCP-5, region 2 has a smaller but still large net charge of +8 in mMCP-4 and +6 in mMCP-5
A stereoplot of electrostatic potential contours around mMCP-4 is shown.
The contour maps of the electrostatic potential for mMBP-1, mMCP-2, mMCP-4, mMCP-5, rMCP- 11, and chymotrypsin are compared.
A schematic model of the interaction of mMCP-4, mMCP- 5, and rMCP-I with heparin is shown. The model for interaction is not sufficiently detailed to distinguish between a specific electrostatic interaction that requires a certain oligosaccharide sequence and an interaction that relies on charge density without many steric restrictions.
