Cyclitol containing carbohydrates from human tissue which regulate lipogenic activity

Abstract

The application relates to the purification and characterization of a family of A-type inositolphosphoglycans (IPGs) from human liver and placenta. These substances are shown to have the biological activity associated with A-type IPG fractions, namely regulating lipogenic activity and inhibiting cAMP dependent protein kinase. The characterization of the compounds demonstrates that they contain metal ions, in particular 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 analogs.

What is claimed is:  
     
         1 . A monoclonal antibody that specifically binds to an isolated A-type substance obtainable from human liver or placenta, wherein the substance is a cyclitol-containing carbohydrate comprising a Zn 2+  ion and has the biological activity of regulating lipogenic activity and inhibiting cAMP dependent protein kinase.  
     
     
         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 A-type substance;    b) binding to the A-type substance and thereby reducing its level; and/or    c) reducing a biological activity of the A-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 A-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 A-type substance in the sample.  
     
     
         10 . The immunoassay method of    claim 9   , additionally comprising determining the concentration of one or more P-type inositolphosphoglycans (IPGs) and then determining the ratio of the concentration of P-type IPG(s) to the concentration of the A-type substance determined in the immunoassay method.  
     
     
         11 . A monoclonal antibody that specifically binds to a A-type cyclitol-containing carbohydrate substance comprising a Zn 2+  ion, wherein the substance has the biological activity of regulating lipogenic activity and inhibiting cAMP dependent protein kinase and: 
 (a) a molecular weight determined using negative mode MALDI mass spectroscopy as shown in tables 3 and 4, or a molecular weight related to one of the molecular weights set out in tables 3 and 4 by the addition or subtraction of one or more structure units of about 211 m/z; or,  
 (b) a molecular weight determined using positive mode MALDI mass spectroscopy as shown in table 5, or a molecular weight related to one of the molecular weights set out in table 5 by the addition or subtraction of one or more structure units of about 211 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 A-type substance;    b) binding to the A-type substance and thereby reducing its level; and/or    c) reducing a biological activity of the A-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 A-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 A-type substance in the sample.  
     
     
         20 . The immunoassay method of    claim 19   , additionally comprising determining the concentration of one or more P-type inositolphosphoglycans (IPGs) and then determining the ratio of the concentration of P-type IPG(s) to the concentration of the A-type substance determined in the immunoassay method.