Adenosylhomocysteinase (AHCY) is a conserved enzyme governing one-carbon metabolism, catalysing reversible hydrolysis of S-adenosyl-L-homocysteine into adenosine and L-homocysteine. As the sole mammalian enzyme clearing S-adenosylhomocysteine, a potent methyltransferase inhibitor, AHCY maintains cellular methylation homeostasis. Its activity shapes DNA, RNA and histone methylation landscapes, regulating cell proliferation, differentiation and epigenetic reprogramming. Dysregulated AHCY expression occurs in multiple malignancies, driving aberrant epigenetic signalling and tumour progression. It participates in intricate epigenetic regulatory networks and interacts with various methyltransferases to coordinate transmethylation reactions essential for normal physiological function. AHCY directly binds DNMT3B to modulate de novo DNA methyltransferase activity and fine-tune genomic DNA methylation levels. Thus a functional ELISA assay was conducted to detect the interaction of recombinant human AHCY and recombinant mouse DNMT3B. Briefly, AHCY was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μL were then transferred to DNMT3B-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-AHCY pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 μL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant human AHCY and recombinan mouset DNMT3B was shown in Figure 1, the EC50?for this effect is 0.500 μg/mL.