How long will it take a protein of molecular weight equal to 90,000 g/mole to diffuse a distance of 1 um?

How long will it take a protein of molecular weight equal to 90,000 g/mole to diffuse a distance of 1 um? Assume the temperature is 37 degrees C, the thermal energy is equal to three halves kbT, and the mean free path is 10-9 cm. Assume that ideal gas ideas apply.