|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1997 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1996 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1995 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Proteasome is a widery distributed protease in cellular organism, which plays an important role in a cell cycle, and proteolyze unneeded proteins to keep the cell being stable.
Eukaryotic proteasomes are multicatalytic proteinase complexes with a molecular weight of 750 kDa, containing, respectively, two copies of a hetero-heptamer of alpha-type subunits and one of beta-type subunits, (alpha1-7beta1-7)2. Proteasome was purified from bovine liver and crystallized into a hexagonal system with cell dimensions of a=b=121.83 (2) *, c=930.68 (6) *. A cylindrical particle size of 122 * diameter and 155* height was determined from the molecular packing in a unit cell. The srystal gave diffraction spots up to at least 4.4 * resolution, which was the minimum spacing of the camera used. The overall temperature factor of the enzyme was estimated to be in the range of 36.2A^2 to 25.8*^2. These results imply that the enzyme complex has a unique ordered structure comprising multisubunits with two types of hetero-heptamer. This ordered structure may facilitate highly organized cooperation of individual functions of subunits within the enzyme complex. And new crystal forms of the proteasome were obtained by changing the concentration of a precipitant, whose dimensions were 1/3 of the previous cell dimension.
An evaluation of the diffraction data from such crystal are now in progress.
In 1997, Prof.R.Huber in Max Plank Inst.clarified the tertiary structure of a yeast proteasome, and disscussed the mechanism of multi-proteolytic function at 2 A resolution. But, immuno-responsibility could not be described due to yeast-system. Therefore, proteasome and its activator are important target to show immuno-system in a Eukaryotic cell.