Patent ID: 8476034

Claim:
A method for assaying homocysteine (Hcy) in a sample without chromatographic separation, 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) contacting the mixture formed in step a) with an adenosylhomocysteine nucleosidase to convert SAH into adenine and S-ribosyl homocysteine; c) contacting the mixture formed in step b) with an S-ribosyl homocysteinase to cycle the S-ribosyl homocysteine into homocysteine; and d) assessing the amount of adenine in the mixture formed in step b) and/or c), whereby the amount of Hcy in the sample is determined from the amount of adenine.