Cyclitol containing carbohydrates from human tissue which regulate glycogen metabolism

Abstract

The application relates to the purification and characterisation of a family of P-type inositolphosphoglycans (IPGs) from human liver and placenta. These substances are shown to have P-type biological activity, e.g. activating pyruvate dehydrogenase (PDH) phosphatase. The characterisation of the compounds demonstrates that they contain metal ions, in particular Mn 2+ and/or Zn 2+ , and optionally phosphate. The compounds and their antagonists have uses as pharmaceuticals, e.g. for the treatment of diabetes, and in screening for synthetic analogues.

What is claimed is:  
     
         1 . A monoclonal antibody that specifically binds to an isolated P-type substance obtainable from human liver or placenta, wherein the substance is a cyclitol-containing carbohydrate comprising Mn 2+  and Zn 2+  ions and has the biological activity of activating pyruvate dehydrogenase (PDH) phosphatase.  
     
     
         2 . The monoclonal antibody of  claim 1  wherein the substance comprises phosphate.  
     
     
         3 . A hybridoma producing the monoclonal antibody of  claim 1 .  
     
     
         4 . A pharmaceutical composition comprising the monoclonal antibody of  claim 1  in combination with a pharmaceutically acceptable carrier.  
     
     
         5 . The monoclonal antibody of  claim 1 , wherein the monoclonal antibody is an antagonist having the property of: 
 a) inhibiting the release of the P-type substance;    b) binding to the P-type substance and thereby reducing its level; and/or    c) reducing a biological activity of the P-type substance.    
     
     
         6 . The monoclonal antibody of  claim 1 , wherein the monoclonal antibody is linked, directly or indirectly, to a label.  
     
     
         7 . The monoclonal antibody of  claim 1 , wherein the monoclonal antibody is immobilized on a solid phase.  
     
     
         8 . An immunoassay method comprising: 
 a) contacting a biological sample with the monoclonal antibody of  claim 1  under suitable conditions for specific binding of the monoclonal antibody to P-type substance present in the sample, if any; and    b) determining whether the monoclonal antibody binds specifically to the sample.    
     
     
         9 . The immunoassay method of  claim 8 , additionally comprising measuring the amount of specific binding as an indication of the concentration of the P-type substance in the sample.  
     
     
         10 . The immunoassay method of  claim 9 , additionally comprising determining the concentration of one or more A-type inositolphosphoglycans (IPGs) and then determining the ratio of the concentration of the P-type substance determined in the immunoassay method to the concentration of A-type IPG(s).  
     
     
         11 . A monoclonal antibody that specifically binds to a P-type cyclitol-containing carbohydrate substance comprising Mn 2+  and Zn 2+  ions, wherein the substance has the biological activity of activating pyruvate dehydrogenase (PDH) phosphatase and a molecular weight determined using negative mode MALDI mass spectroscopy as shown in FIG. 11, or a molecular weight related to one of the molecular weights set out in FIG. 11 by the addition or subtraction of one or more structure units of about 236 m/z.  
     
     
         12 . The monoclonal antibody of  claim 11  wherein the substance comprises phosphate.  
     
     
         13 . A hybridoma producing the monoclonal antibody of  claim 11 .  
     
     
         14 . A pharmaceutical composition comprising the monoclonal antibody of  claim 11  in combination with a pharmaceutically acceptable carrier.  
     
     
         15 . The monoclonal antibody of  claim 11 , wherein the monoclonal antibody is an antagonist having the property of: 
 a) inhibiting the release of the P-type substance;    b) binding to the P-type substance and thereby reducing its level; and/or    c) reducing a biological activity of the P-type substance.    
     
     
         16 . The monoclonal antibody of  claim 11 , wherein the monoclonal antibody is linked, directly or indirectly, to a label.  
     
     
         17 . The monoclonal antibody of  claim 11 , wherein the monoclonal antibody is immobilized on a solid phase.  
     
     
         18 . An immunoassay method comprising: 
 a) contacting a biological sample with the monoclonal antibody of  claim 11  under suitable conditions for specific binding of the monoclonal antibody to P-type substance present in the sample, if any; and    b) determining whether the monoclonal antibody binds specifically to the sample.    
     
     
         19 . The immunoassay method of  claim 18 , additionally comprising measuring the amount of specific binding as an indication of the concentration of the P-type substance in the sample.  
     
     
         20 . The immunoassay method of  claim 19 , additionally comprising determining the concentration of one or more A-type inositolphosphoglycans (IPGs) and then determining the ratio of the concentration of the P-type substance determined in the immunoassay method to the concentration of A-type IPG(s).