The role of propeptide in the refolding of human group IB phospholipase A2

Human group IB phospholipase A(2) (IB-PLA(2)) and its zymogen (proIB-PLA(2)) were purified from E. colt. Refolding was carried out by diluting the denatured forms of both IB-PLA(2) and proIB-PLA(2) with renaturation buffer in which the disulfide bonds were completely reduced. The refolding yield of proIB-PLA(2) was increased by about 50% over that of the mature enzyme. The refolding of IB-PLA(2) usually produced aggregates under normal conditions, as determined by light scattering. In addition, the unfolding experiments showed that the mature enzyme was more stable than the proenzyme toward denaturants in the presence of DTT. Results suggested that the N-terminal sequence rather than its conformation of human prolB-PLA(2) played an important role in the refolding process.