Effects of macromolecular crowding on the unfolding and the refolding of D-glyceraldehyde-3-phosophospate dehydrogenase.

The effects of crowding agents, polyethylene glycol (PEG 20K), Dextran 70, and bovine serum albumin, on the denaturation of homotetrameric D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) in 0.5 M guanidine hydrochloride and the reactivation of the fully denatured enzyme have been examined quantitatively. Increasing the concentration of PEG 20K to 225 mg/ml decreases the rate constant of slow phase of GAPDH inactivation to 5% but with no change for the fast phase. Chaperone GroEL assists GAPDH refolding greatly and shows even higher efficiency under crowding condition. Crowding mainly affects refolding steps after the formation of the dimeric folding intermediate.

Post-genome Study----Proteomics.

The human genome project was launched in 1990. Although only 3% of the total DNA sequence have been analyzed, the study of the functional genome is already on the agenda and the post genomic era is already with us. The aim of the new era, the era of the proteomics, is to elucidate the expression, structure and function of all the proteins which are after all responsible for life's activities. The main techniques for the separation and identification of all the expressed proteins are two-dimentional gel electrophoresis, two-dimentional HPLC, mass spectrometry and bioinformatics. Proteome research is not only the major task in life sciences facing us in the 21st century, but also has far reaching implications in innovations for medicine, agriculture and industrial production.