Recombinant Mycobacterium tuberculosis ESAT-6-like protein esxB (esxB)

Thanks for your inquiry.The Expiration of the protein is related to several factors. For example the keep situation, the buffer, the tempreture, and also the stability of the protein.
Usually the liquid format protein keep in -20℃/-80℃, the expiration period is about 6 months. The lyophilize format protein keep in -20℃/-80℃, the expiration period is about 12 months.
If you have keep for a long time, we suggest do the SDS-PAGE to check first. And also check the relevant activity according to the different experiment requirements. If the protein have degradation o ragglomeration, the protein need to purchase again. If so we could offer some discount for it.