Design of peptides with high affinities for heparin and endothelial cell proteoglycans.
Proteoglycan-binding peptides were designed based on consensus sequences in heparin-binding proteins: XBBXBX and XBBBXXBX, where X and B are hydropathic and basic residues, respectively. Initial peptide constructs included (AKKARA)(n) and (ARKKAAKA)(n) (n = 1-6). Affinity coelectrophoresis revealed that low M(r) peptides (600-1,300) had no affinities for low M(r) heparin, but higher M(r) peptides (2,000-3,500) exhibited significant affinities (K(d) congruent with 50-150 nM), which increased with peptide M(r). Affinity was strongest when sequence arrays were contiguous and alanines and arginines occupied hydropathic and basic positions, but inclusion of prolines was disruptive. A peptide including a single consensus sequence of the serglycin proteoglycan core protein bound heparin strongly (K(d) congruent with 200 nM), likely owing to dimerization through cysteine-cysteine linkages. Circular dichroism showed that high affinity heparin-binding peptides converted from a charged coil to an alpha-helix upon heparin addition, whereas weak heparin-binding peptides did not. Higher M(r) peptides exhibited high affinities for total endothelial cell proteoglycans (K(d) congruent with 300 nM), and approximately 4-fold weaker affinities for their free glycosaminoglycan chains. Thus, peptides including concatamers of heparin-binding consensus sequences may exhibit strong affinities for heparin and proteoglycans. Such peptides may be applicable in promoting cell-substratum adhesion or in the design of drugs targeted to proteoglycan-containing cell surfaces and extracellular matrices.
Verrecchio
A
A
Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Germann
M W
MW
Schick
B P
BP
Kung
B
B
Twardowski
T
T
San Antonio
J D
JD
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D016384:Consensus Sequence; D004730:Endothelium, Vascular / Q000737:chemistry*; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism*; D011485:Protein Binding; D011509:Proteoglycans / Q000378:metabolism*
D009842:Oligopeptides; D010455:Peptides; D011509:Proteoglycans; D006493:Heparin