Differential labelling method

Abstract

The invention relates to a method for differentially labelling one or more entities, together comprising distinct reactive sites. The invention further relates to an entity that has been labelled by a method according to the invention and to a diagnostic kit comprising a labelled entity and to a diagnostic kit to employ a method according to the invention.

1 . A method for selectively forming a complex of a platinum compound and a sulphur-containing reactive site of an entity or of at least one entity of a mixture of two or more entities, the entity or the mixture of two or more entities comprising one or more sulphur-containing reactive sites and one or more nitrogen-containing reactive sites, the method comprising:
 forming a complex of the platinum compound and the entity or the at least one entity of a mixture of two or more entities at a pH below the lowest pKa of the nitrogen-containing reactive sites, whereby the platinum compound is reacted with the entity such that substantially only sulphur-containing reactive sites are linked to the platinum compound;   thereby selectively forming a complex of a platinum compound and a sulphur-containing reactive site of an entity or of at least one entity of a mixture of two or more entities.   
     
     
         2 . A method according to  claim 1 , wherein the entity or the entities are selected from the group consisting of amino acids, peptides, oligopeptides, polypeptides, proteins, immunoglobulins, enzymes, synzymes, phospholipids, glycoproteins, nucleic acids, nucleosides, nucleotides, oligonucleotides, polynucleotides, peptide nucleic acids, peptide nucleic acid oligomers, peptide nucleic acid polymers, amines and aminoglycosides. 
     
     
         3 . A method according to  claim 1 , wherein the pH is 5 or less. 
     
     
         4 . A method according to  claim 1 , wherein the platinum compound comprises a label. 
     
     
         5 . A method according to  claim 1 , wherein the platinum compound is a trans platinum compound. 
     
     
         6 . A method for differentially forming a complex of a first platinum compound and a sulphur-containing reactive site of an entity or of at least one entity of a mixture of two or more entities, and a second platinum compound and a nitrogen-containing reactive site of the entity or of at least one entity of the mixture of two or more entities, the entity or the mixture of two or more entities comprising one or more sulphur-containing reactive sites and one or more nitrogen-containing reactive sites, the method comprising:
 (a) forming a first complex of the first platinum compound and the entity or the at least one entity of a mixture of two or more entities at a pH below the lowest pKa of the nitrogen-containing reactive sites, whereby the first platinum compound is reacted with the entity such that substantially none of the nitrogen-containing reactive sites, and substantially all of the sulphur-containing reactive sites, are linked to the first platinum compound; and   (b) starting with the first complex, forming a second complex of the second platinum compound and the entity or the at least one entity of a mixture of two or more entities at a pH at which only nitrogen-containing reactive sites are linked to the second platinum compound;   thereby differentially forming a complex of a first platinum compound and a sulphur-containing reactive site of an entity or of at least one entity of a mixture of two or more entities, and a second platinum compound and a nitrogen-containing reactive site of the entity or at least one entity of the mixture of two or more entities.   
     
     
         7 . A method according to  claim 6 , wherein the entity or the entities are selected from the group consisting of amino acids, peptides, oligopeptides, polypeptides, proteins, immunoglobulins, enzymes, synzymes, phospholipids, glycoproteins, nucleic acids, nucleosides, nucleotides, oligonucleotides, polynucleotides, peptide nucleic acids, peptide nucleic acid oligomers, peptide nucleic acid polymers, amines and aminoglycosides. 
     
     
         8 . A method according to  claim 6 , wherein the pH in part (a) is 5 or less. 
     
     
         9 . A method according to  claim 6 , wherein the pH in part (b) is 7 or above. 
     
     
         10 . A method according to  claim 6 , wherein the first platinum compound comprises a label. 
     
     
         11 . A method according to  claim 6 , wherein the second platinum compound comprises a label. 
     
     
         12 . A method according to  claim 6 , wherein the first platinum compound is a trans platinum compound. 
     
     
         13 . A method according to  claim 12 , wherein the trans platinum compound comprises a label. 
     
     
         14 . A method according to  claim 13 , wherein the label is removed from the trans platinum compound. 
     
     
         15 . A method according to  claim 13 , wherein the first platinum compound and the second platinum compound are the same trans platinum compound comprising a label, further comprising removing the label of the first trans platinum compound.