What artificial substrate is used in enzymatic assays for Tay-Sachs disease testing?

• A. GlcNAc
• B. 4-methylumbelliferone
• C. Mu
• D. Acetylcholine

Answer: (B)

The artificial substrate used in enzymatic assays for Tay-Sachs disease testing is 4-methylumbelliferone. This specific substrate is chosen because it provides a measurable fluorescent signal upon hydrolysis by the enzyme hexosaminidase A, which is deficient in individuals with Tay-Sachs disease.

During the assay, when hexosaminidase A is active, it cleaves 4-methylumbelliferone from the substrate, leading to the release of a fluorescent compound. The intensity of the fluorescence can be quantified and indicates the enzyme activity level. In the absence of sufficient enzyme activity, as seen in Tay-Sachs patients, the fluorescence will be significantly lower, which is critical for diagnosing the condition.

Other options such as GlcNAc, Mu, and Acetylcholine do not serve as effective substrates in this particular context, as they do not produce the specific fluorescence signal utilized for diagnosing Tay-Sachs.