Effects of a High-Pressure Treatment on the Activity and Structure of Rabbit Muscle Proteasome
作者:Shuhei YAMAMOTO、Yuichi OTSUKA、Gerelt BORJIGIN、Kanna MASUDA、Yoshihide IKEUCHI、Tadayuki NISHIUMI、Atsushi SUZUKI
DOI:10.1271/bbb.69.1239
日期:2005.1
The effects were assessed of high hydrostatic pressure on the activity and structure of rabbit skeletal muscle proteasome. The pressure effects on the activity were measured by the amount of fluorometric products released from synthetic substrates under pressure and from fluorescein isothiocyanate (FITC)-labeled casein after releasing the pressure. The effects on the structure were measured by fluorescene spectroscopy under pressure, and by circular dichroism (CD) spectroscopy and surface hydrophobicity after releasing the pressure. The optimal pressure for the hydrolyzing activity of synthetic peptides was 50 MPa. The degradation of FITC-labeled casein increased linearly with increasing pressure applied up to 200 MPa, and then markedly decreased up to at 400 MPa.The changes in the tertiary structure detected by fluorometric measurement were irreversible, whereas the changes in the secondary structure were small compared with those by heat treatment. The pressure-induced activation of proteasome therefore seems to have been due to a little unfolding of the active sites of proteasome.
评估了高静水压对家兔骨骼肌蛋白酶体的活性和结构的影响。压力对活性的影响是通过合成底物在压力下释放的荧光产物量以及释放压力后荧光素异硫氰酸酯(FITC)标记的酪蛋白释放的荧光产物量来测量的。压力下的荧光光谱以及释放压力后的圆二色性(CD)光谱和表面疏水性测量了对结构的影响。合成肽水解活性的最佳压力为 50 兆帕。FITC标记的酪蛋白的降解随压力的增加而线性增加,最高达200兆帕,然后在400兆帕时明显降低。通过荧光测定法检测到的三级结构的变化是不可逆的,而二级结构的变化与热处理的变化相比很小。因此,压力诱导的蛋白酶体活化似乎是由于蛋白酶体活性位点的少许折叠所致。