Increased potency of an erythropoietin peptide mimetic through covalent dimerization.
We have synthesized a chemically defined, dimeric form of an erythropoietin mimetic peptide (EMP) that displays 100-fold increased affinity for the erythropoietin receptor (EPOR) and correspondingly elevated potency in cell-based assays and in mice. The dimeric EMP1 was synthesized using a C-terminal lysine residue as a branch point. A beta-alanine residue was coupled to the main-chain (alpha) amino group of the lysine residue in order to provide a pseudosymmetrical scaffold where both the side-chain and main-chain were of approximately equal length. Using an orthogonal protection system, independently disulphide-cylized EMP1 moieties were synthesized upon this scaffold. The proposed mechanism of increased potency of the dimer over the parental compound EMP1 is consistent with the structure of a cocrystal of EMP1 and the extracellular domain of the EPOR in which a noncovalent peptide dimer is seen spanning the cleft between two molecules of the EPOR extracellular domain.
Wrighton
N C
NC
Affymax Research Institute, Palo Alto, CA 94304, USA. nick@wrighton.com
Balasubramanian
P
P
Barbone
F P
FP
Kashyap
A K
AK
Farrell
F X
FX
Jolliffe
L K
LK
Barrett
R W
RW
Dower
W J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D019281:Dimerization; D004921:Erythropoietin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D017467:Receptors, Erythropoietin / Q000378:metabolism
D010455:Peptides; D017467:Receptors, Erythropoietin; D004921:Erythropoietin