Methods and compositions for assaying homocysteine

Abstract

This invention relates generally to the field of homocysteine detection. In particular, the invention provides a method for determining homocysteine presence or concentration in samples, which method comprises: contacting a sample containing or suspected of containing Hcy with a Hcy co-substrate and a Hcy converting enzyme in a Hcy conversion reaction to form a Hcy conversion product and a Hcy co-substrate conversion product; and assessing the Hcy co-substrate conversion product to determine the presence, absence and/or amount of the Hcy in the sample. A kit for assaying homocysteine based on the same principle is also provided.

1 - 13 . (canceled)  
     
     
         14 . A method for assaying homocysteine (Hcy) in a sample, which method comprises: 
 a) contacting a sample containing or suspected of containing Hcy with a Hcy co-substrate and a Hcy converting enzyme in a Hcy conversion reaction to form a Hcy conversion product and a Hcy co-substrate conversion product, wherein the Hcy co-substrate is S-adenosylmethionine (SAM), the Hcy converting enzyme is a S-adenosylmethionine (SAM)-dependent homocysteine S-methyltransferase, the Hcy conversion product is methionine (Met) and the Hcy co-substrate conversion product is S-adenosyl-L-homocysteine (SAH),    b) assessing the Hcy co-substrate conversion product SAH to determine the presence, absence and/or amount of the Hcy in the sample, wherein the SAH is assessed without chromatographic separation.    
     
     
         15 . The method of  claim 14 , wherein the assessment of SAH does not involve an enzymatic reaction generating H 2 O 2  and detection of H 2 O 2 .  
     
     
         16 . The method of  claim 14 , wherein the SAM is added to the sample.  
     
     
         17 . The method of  claim 14 , wherein the SAM is produced from ATP and Met by a SAM synthase.  
     
     
         18 - 20 . (canceled)  
     
     
         21 . A kit for assaying Hcy in a sample, which kit comprises: 
 a) a S-adenosylmethionine (SAM)-dependent homocysteine S-methyltransferase;    b) S-adenosylmethionine (SAM) or ATP, Met and a SAM synthase; and    c) a reagent for assessing SAH,    wherein the kit does not comprise an enzyme or a reagent for generating H 2 O 2  and a reagent for detecting H 2 O 2 .