Enzyme X is immobilized to a support and is used to separate substrate Y from a mixture of other compounds. In a separate experiment the rate constant for the dissociation of substrate Y from enzyme X was determined to be 1.3 x 10-5 s-1. Suggest mobile phase conditions that would be best for eluting substrate Y after washing away the interfering compounds.

To select the best mobile phase conditions for eluting substrate Y after washing away interfering compounds, we need to consider the properties of the substrate and the support-bound enzyme.

Firstly, we should focus on finding a mobile phase that provides the appropriate elution strength to dissociate substrate Y from enzyme X. The dissociation rate constant (k) of substrate Y from enzyme X is given as 1.3 x 10-5 s-1. A higher k value indicates faster dissociation, while a lower k value suggests slower dissociation. Considering the dissociation rate constant, we can select mobile phase conditions that favor the dissociation of substrate Y from enzyme X.

Here's a step-by-step approach to finding the best mobile phase conditions:

1. Determine the nature of substrate Y:
- Consider the solubility of substrate Y in various solvents or solvent mixtures.
- Identify any known interactions (e.g., ionic, hydrophobic, etc.) between substrate Y and the enzyme or support.

2. Consider the elution strength:
- Based on the dissociation rate constant, a relatively weaker eluting mobile phase might be needed to allow sufficient time for the substrate to dissociate from the enzyme.
- Choose a mobile phase that does not denature the enzyme or irreversibly interact with the support-bound enzyme.

3. Evaluate the composition of the mobile phase:
- Consider using a solvent or a solvent mixture that can disrupt any specific interactions between substrate Y and the support-bound enzyme. For example, if the substrate is hydrophobic and binds strongly to the support, using a polar solvent or increasing the polarity of the mobile phase may help elute the substrate.
- You can also try adjusting pH, temperature, or the addition of small amounts of salts or organic modifiers to optimize the elution conditions.

4. Test the selected mobile phase:
- Prepare various mobile phase compositions and perform experiments (e.g., chromatography) to test substrate Y's elution under different conditions.
- Assess the elution profile, separation efficiency, and recovery of substrate Y to determine the optimal mobile phase conditions.

Remember that the suitability of a mobile phase depends on the specific characteristics of the substrate, enzyme, and support system. Therefore, it might be necessary to conduct multiple experiments and optimize the mobile phase conditions for effective elution of substrate Y while minimizing interference from other compounds.