| 摘要 |
Methods for assaying methyl transfer reactions e.g., methyltransferase (MT) activity and in particular S-adenosylmethionine (SAM) dependent MT activity by spectrophotometric analysis at a wavelength of 300nm or above. The methyltransferases require S-adenosylmethionine (SAM) as the source of the methyl group. On transferring the methyl group SAM generates S-adenosylhomocysteine (SAH) which is cleaved by a nucleosidease to give S-ribosylhomocysteine and adenine. The adenine is deaminated to provide ammonia which may be analysed by the addition of α-ketoglutarate, NADPH and glutamate dehydrogenase, wherein the consumption of NADPH is followed at 340nm. Additional enzymatic coupled reactions to the generation of ammonia may provide pyruvate or hydrogen peroxide. |
