Method of generating metal chelating affinity ligands

Abstract

The present invention relates to a method of generating at least one polydentate metal chelating affinity ligand, which method comprises the steps of (a) providing at least one cyclic scaffold comprising a carbonyl, an adjacent sulphur and a nucleophile; (b) providing at least one polydentate metal chelating affinity ligand arm, optionally in a form wherein the metal chelating functionalities are protected, on each scaffold by derivatisation of the nucleophile of said scaffolds, while retaining the cyclic structure of the scaffold; (c) ring-opening at the bond between the carbonyl and the sulphur of the derivatised scaffold by adding a reagent that adds one or more metal chelating affinity ligand arms to the scaffold; and, if required, (d) deprotecting the functionalities of the ligand arm(s) provided in step (b). In the most preferred embodiment of the method, steps (c) and (d) are performed simultaneously as one single step.

1 - 16 . (canceled)  
     
     
         17 . A polydentate metal chelating affinity ligand, or a separation medium comprising a plurality of polydentate metal chelating affinity ligands coupled to a base matrix wherein said ligands are generated by a method comprising the steps of: 
 (a) providing at least one scaffold defined by a ring of the general formula (I)                          wherein    X 1 , X 2  and X 3  irrespective of each other are sp 2 - or sp 3 -hybridised carbon atoms or heteroatoms,    X 4  is a nucleophile and    m is an integer of 0-2;    (b) providing at least one polydentate metal chelating affinity ligand arm on each scaffold by derivatisation of the nucleophilic X 4  groups of said scaffolds while retaining the cyclic structure of the scaffold; and    (c) opening the ring at a bond between the carbonyl and the sulphur of the derivatised scaffold by adding a reagent that adds one or more metal chelating affinity ligand arms to the scaffold.    
     
     
         18 . The ligand or separation medium of  claim 17 , wherein the ligand is a tridentate ligand.  
     
     
         19 - 20 . (canceled)  
     
     
         21 . A separation medium comprising polydentate metal chelating affinity ligands coupled to a base matrix and defined by the general formula base matrix—O—CH 2 —CHOH—CH 2 —O—CH 2 —CHOH—CH 2 S—(CH 2 )n—CH(COOH)—N(CH 2 COO − ) 2 Ni 2+  wherein n is an integer of 2-4.  
     
     
         22 . The medium of  claim 21 , wherein n=2.  
     
     
         23 . A chromatography column for immobilised metal ion adsorption chromatography (IMAC), packed with the separation medium of  claim 17 .  
     
     
         24 . A process of separating a target substance from a liquid, which process comprises providing the separation medium of  claim 17  to charge said medium with suitable metal ions to form chelates and to contact said medium with the liquid to adsorb the target substance thereon.  
     
     
         25 . The process of  claim 24 , further comprising a step of eluting the target substance from the separation medium by adding a liquid that desorbs the target compound from the separation medium.  
     
     
         26 . The process of  claim 25 , wherein the eluting is obtained by use of a liquid that comprises a decreasing pH gradient or by applying a gradient of increasing imidazole concentration.