Ribosome-inactivating proteins (RIPs) are toxic enzymes that are mostly biosynthesized by plants. RIPs are N-glycosidases that cleave an essential adenine molecule from the 28S rRNA. This is followed by the irreversible inhibition of protein synthesis leading to cell death. By fusing RIPs to cancer cell specific targeting ligands RIPs have been utilized for targeted anti-tumor therapy. The anti-tumoral efficiency of such conjugates depends significantly on the N-glycosidase activity of the RIP domain.

Different methods have been developed in order to determine the N-glycosidase activity of RIPs and RIP domain containing anti-tumor toxins. However the existing methods are elaborate and include radioassays, HPLC and enzymatic conversion assays.

Here, a simple and cost effective N-glycosidase assay is presented, which is based on the direct determination of the released adenine by thin-layer chromatography (TLC) and TLC-densitometry. An adenine based single stranded oligonucleotide is used as substrate. Following TLC development the released adenine is quantified on silica glass plates by UV absorbance at 260 nm.

核糖体失活蛋白（RIPs）是有毒的酶，大部分是由植物生物合成的。RIP是从28S rRNA切割必不可少的腺嘌呤分子的N-糖苷酶。其次是对蛋白质合成的不可逆抑制，导致细胞死亡。通过将RIP融合至癌细胞的特异性靶向配体，RIP已用于靶向抗肿瘤治疗。此类缀合物的抗肿瘤效率极大地取决于RIP结构域的N-糖苷酶活性。

为了确定RIP和含有抗肿瘤毒素的RIP结构域的N-糖苷酶活性，已经开发了不同的方法。但是，现有方法很复杂，包括放射分析，HPLC和酶促转化分析。

在此，提出了一种简单且具有成本效益的N-糖苷酶测定法，该测定法是基于通过薄层色谱法（TLC）和TLC密度测定法直接测定释放的腺嘌呤。基于腺嘌呤的单链寡核苷酸用作底物。在TLC显影之后，通过在260nm下的UV吸收在二氧化硅玻璃板上对释放的腺嘌呤进行定量。