Abstract: A method to assess the level of folate in a biological sample comprises: providing said sample with glycine N-methyltransferase (GMT) and with an excess of S-adenosyl methionine (SAM) and of glycine; providing a control which contains no folate with said GMT and excess SAM and glycine in comparable amounts to those provided to the sample; and comparing the concentration of at least one product formed in the sample with the concentrations of said product formed in the control, whereby the difference in levels of said product in the sample as compared to the control is directly proportional to the level of folate in the sample.

Abstract: Novel enzymatic methods to determine the concentration of homocysteine in biological fluids are described. In a typical embodiment of the invention, the biological fluid sample is from a patient, and the methods of the invention are useful to assess risk for cardiovascular disease. The novel methods of the invention involve use of particular homocysteinase enzymes that permit the determination of homocysteine concentrations in biological samples without interference from the concentrations of cysteine and/or of methionine that are routinely present in such samples. There is also provided a diagnostic kit for use in determining the amount of homocysteine in a biological sample comprising (a) a homocysteinase having the aforementioned characteristics, and (b) at least one reagent capable of being used to determine the amount of product formed in the homocysteinase reaction.

Abstract: The present invention describes methods for using methioninase as an antitumor reagent in anti-methionine chemotherapy. Specifically, methioninase is used to slow or stop cell division which can be enhanced with competitive inhibitors of methionine. In addition, methioninase can be used in combination with chemotherapeutic agents to increase the therapeutic effectiveness of the agent by inducing cell cycle synchronization.