Exposure of more hydrophobic residues that somehow increase the affinity recognition process.

Here is a paper that investigates this effect for one enzyme:

Article Effects of organic solvents on the enzyme activity of Trypan...

I tried 20% ethanol during beta-Lg hydrolysis by trypsin, at least the hydrolysis efficacy was not decreased, and the intact protein molecule was more preferred by trypsin. The change of accessibility of hydrophobic part could be one of the important reasons.

Thanks for your answers but the interesting question is , how two similar organic solvents (methanol and ethanol ) have opposite effect on the same enzyme ? I could not comment that

They are only similar in their functional group. The difference is established by the number of carbons. Ethanol is a little more hydrophobic than methanol.