Studies on the denaturation of muscle proteins under high pressure.

采用组织学、生化和理化方法研究了高压下肌肉蛋白的变性。在2.055 ppm时，核磁共振信号消失；在300 MPa时，生物化学活性（DNAasel抑制能力、聚合能力）的损失几乎相同。提示肌动蛋白分子“尖端”上部区域的空间结构在结合的核苷酸解离后迅速瓦解。2) α-螺旋含量随压力的增加而降低，且在300 MPa及以上压力下肌动蛋白变性不可逆。1)在200 MPa及以上压力下，肌球蛋白分子的结构变化是不可逆的。2)原肌球蛋白不仅耐酸、耐热，而且耐高压。线粒体和结结组织1)Ca^<2+>摄取能力的降低似乎与atp酶活性的降低有关，这可能是由于atp酶亚基（α β）在压力作用下从线粒体释放所致。2)随着压力的增加，肌内膜蜂窝状结构的变形加快，但加压肌中pg的可提取性未见变化。蛋白酶体高达50 ~ 100MPa的高压处理引起蛋白酶体的活化。这种激活可能是由于底物与高压处理下展开的蛋白酶体活性位点的相互作用增加。β-乳球蛋白（BLg）与高压解冻1)加压与不加压BLg的^1NMR谱无差异。对芳香残基H/D交换的核磁共振检测表明，释放压力后，色氨酸残基附近的构象可以重新折叠。2)明确了高压解冻法适用于肉类加工。

The denaturation of muscle proteins under high pressure was investigated by histological, biochemical and physicochemical methods.Actin1) The rate of dissociation of nucleotides from actin molecule, disappearance of the characterized ^1H NMR signal at 2.055 ppm and loss in biochemical activities (DNAasel inhibition capacity, polymerizability) at 300 MPa were almost identical. suggesting that the rapid collapse of steric structure around the upper region called "pointed end" of actin molecule following the dissociation of the bound nucleotide.2) The decreases of α-helix content were observed with the pressure applied and the denaturation was irreversible in the actin pressurized at 300 MPa or more.Myosin and Tropomyosin1) The structural changes in myosin molecule pressurized at 200 MPa or more were irreversible.2) Tropomyosin which is resistive to acid and heat was also resistive to high pressure.Mitochondria and Connective Tissue1) The decrease of Ca^<2+> uptaking ability seemed to be correlated with the decrease of ATPase activity which may be caused by the release of ATPase subunits (α β) from mitochondria by pressure.2) The deformation of the honeycomb-like structure of endomysium was accelerated with increase of pressure applied, but the changes in the extractability of PGs were not observed in the pressurized muscle.ProteasomeThe high pressure treatments up to 50〜100MPa caused the activation of the proteasome. This activation is probably due to the increase of the interaction of the substrate and active site of the proteasome unfolded by high pressure treatment.β-Lactoglobulin (BLg) and High Pressure-Thawing1) No difference in the ^1NMR spectrum was observed between pressurized and unpressurized BLg. NMR detection of the H/D exchange of aromatic residues indicated that the conformation at the vicinity of tryptophan residues can be refolded after the release of pressure.2) It was cleared that the high pressure-thawing was applicable to meat processing.