PT  - JOURNAL ARTICLE
AU  - Pennington, M. W.
AU  - Beeton, C.
AU  - Galea, C. A.
AU  - Smith, B. J.
AU  - Chi, V.
AU  - Monaghan, K. P.
AU  - Garcia, A.
AU  - Rangaraju, S.
AU  - Giuffrida, A.
AU  - Plank, D.
AU  - Crossley, G.
AU  - Nugent, D.
AU  - Khaytin, I.
AU  - LeFievre, Y.
AU  - Peshenko, I.
AU  - Dixon, C.
AU  - Chauhan, S.
AU  - Orzel, A.
AU  - Inoue, T.
AU  - Hu, X.
AU  - Moore, R. V.
AU  - Norton, R. S.
AU  - Chandy, K. G.
TI  - Engineering a Stable and Selective Peptide Blocker of the Kv1.3 Channel in T Lymphocytes
AID  - 10.1124/mol.108.052704
DP  - 2009 Apr 01
TA  - Molecular Pharmacology
PG  - 762--773
VI  - 75
IP  - 4
4099  - http://molpharm.aspetjournals.org/content/75/4/762.short
4100  - http://molpharm.aspetjournals.org/content/75/4/762.full
SO  - Mol Pharmacol2009 Apr 01; 75
AB  - Kv1.3 potassium channels maintain the membrane potential of effector memory (TEM) T cells that are important mediators of multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis. The polypeptide ShK-170 (ShK-L5), containing an N-terminal phosphotyrosine extension of the Stichodactyla helianthus ShK toxin, is a potent and selective blocker of these channels. However, a stability study of ShK-170 showed minor pH-related hydrolysis and oxidation byproducts that were exacerbated by increasing temperatures. We therefore engineered a series of analogs to minimize the formation of these byproducts. The analog with the greatest stability, ShK-192, contains a nonhydrolyzable phosphotyrosine surrogate, a methionine isostere, and a C-terminal amide. ShK-192 shows the same overall fold as ShK, and there is no evidence of any interaction between the N-terminal adduct and the rest of the peptide. The docking configuration of ShK-192 in Kv1.3 shows the N-terminal para-phosphonophenylalanine group lying at the junction of two channel monomers to form a salt bridge with Lys411 of the channel. ShK-192 blocks Kv1.3 with an IC50 of 140 pM and exhibits greater than 100-fold selectivity over closely related channels. After a single subcutaneous injection of 100 μg/kg, ∼100 to 200 pM concentrations of active peptide is detectable in the blood of Lewis rats 24, 48, and 72 h after the injection. ShK-192 effectively inhibits the proliferation of TEM cells and suppresses delayed type hypersensitivity when administered at 10 or 100 μg/kg by subcutaneous injection once daily. ShK-192 has potential as a therapeutic for autoimmune diseases mediated by TEM cells. The American Society for Pharmacology and Experimental Therapeutics