The figure below shows the result of a competition assay des

The figure below shows the result of a competition assay designed to identify which of the Zona Pellucida proteins initially binds to sperm. Purified preparations of each of the zona pellucida proteins, ZP1, ZP2, and ZP3, were prepared and incubated with intact sperm. These sperm were then exposed to eggs and the % sperm that bound to the eggs were determined. The % sperm binding is shown of the Y axis and the added exogenous zona pellucida equivalents are shown on the X axis. Which protein binds most effectively to the sperm? Explain your reasoning. What is the significance of the ZP3 without carbohydrates part of the experiment?

Solution

From the figure it is clear that sperm showed maxmum affinity towards Zona pellucida protein ZP1 compared to ZP2 and ZP3, with and without carbohydrates.

It is clear from the figure that about 100% of sperms remained attracted towards ZP 1 protein throughout where as there was a drop in affinity towards ZP2 and ZP3.

However the presence of carbohydrated in the protein mixture of ZP3 improved the affinity of sperm towards the protein, this could be due to the fact that carbohydrates provide free energy to the sperms and therefor remain there a little longer compared to the normal ZP3 protein without carbohydrates.