ISSN:
0887-3585
Keywords:
α-helix
;
lysine residues
;
disaccharide units
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
A model of heparin bound to bovine platelet factor 4 (BPF4) was completed using a graphically designed heparin molecule and the crystallographic coordinates of the native bovine platelet factor 4 tetramer. The oligosaccharides had a chain length of at least eight disaccharide units with the major repeating disaccharide unit consisting of (I→4)-O-(α-L-idopyranosyluronic acid 2-sulfate)-(l→4)-(2-deoxy-2-sulfamino-2-D-glucopyra-nosyl 6-sulfate). Each disaccharide unit carried a -4.0 charge. The structure of BPF4 was solved to 2.6 Å resolution with R = 0.237. Each monomer of BPF4 contains an α-helix lying across 3 strands of antiparallel β-sheet. Each helix has four lysines, which have been implicated in heparin binding. These lysine residues are predominantly on one side of the helix and are solvent accessible. Electrostatic calculations performed on the BPF4 tetramer show a ring of strong, positive charge which runs perpendicularly across the helices. Included in this ring of density is His-38, which has been shown by NMR to have a large pKa shift when heparin binds to BPF4. Our model of heparin bound to PF4 has the anionic polysaccharide perpendicular to the α-helices, wrapped about the tetramer along the ring of positive charge, and salt linked to all four lysines on the helix of each monomer. © 1992 Wiley-Liss, Inc.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prot.340140213
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