Patent ID: 6030941
Filing Date: 2000-02-29
Classification: A61K

Abstract:
A composition for transporting a compound from a low-pH environment across a lipid layer to a higher-pH aqueous compartment, said composition comprising(a) a polypeptide containing two or more pairs of side chain carboxyl groups, where(i) the carboxyl groups of a pair are separated by zero, two or three amino acids,(ii) the polypeptide contains, at at least one terminus, an initiator sequence consisting of 5-10 amino acid residues, wherein the ratio of non-acid side chain, lipophilic residues to acid side chain residues is greater than 1, to facilitate entry of said terminus into the lipid layer,(iii) the sequence of the balance of the polypeptide is selected from (EXXXE)n, (XEXXE)n, and (EXEEXEXX)n, where E represents Glu or Asp, X represents a non-acid side chain amino acid, and n is an integer effective to give a total polypeptide length of up to 100 amino acid residues;whereby the polypeptide exhibits solubility in both hydrophilic and lipophilic environments by undergoing a reversible transition between a lipophilic form, effective to partition from said low-pH environment into the lipid layer, and a hydrophilic form, effective to partition preferentially from the lipid layer into the higher-pH aqueous compartment, and is able to traverse the lipid layer from the low-pH environment to the higher-pH compartment, and(b) the compound to be transported, covalently attached to the polypeptide.