Odessey R
Metabolism. 1986 Aug;35(8):750-7. doi: 10.1016/0026-0495(86)90243-x.
A localized burn injury to a rat hindlimb was used to investigate the proteolytic enzymes responsible for the burn-induced increase in muscle protein breakdown. In 10,000 x g pellets of muscle homogenates, burn stimulated (50% to 100%) protease activities with pH optima of 3, 5.5, and 7.8. Burn also stimulated acid protease activity in 27,000 x g supernatants derived from triton X100 treated extracts of muscle. Pretreatment of rats with compound 48/80 (to eliminate contaminating mast cells) eliminated 95% of the neutral protease activity in the particulate fraction. The Ca++-sensitive neutral protease was not affected by either burn or 48/80 treatment. However, muscle extracts from the burned leg always showed a 40% to 70% increase in acid protease activity. All of the acid protease activity could be inhibited by a combination of cathepsin inhibitors pepstatin (0.01 microgram/mL) and leupeptin (1 mumol/L) and leupeptin (1 mumol/L) or Ep475 (1 microgram/mL). Leupeptin and the lysosomotropic agent leucine methyl ester also inhibited the burn-induced proteolysis in intact muscle. A time course shows parallel increases in whole muscle proteolysis and acid protease activity of muscle homogenates. These findings support the conclusion that the increase in lysosomal cathepsins are sufficient to account for the burn-induced increase in protein breakdown in muscles from the injured leg.
利用大鼠后肢局部烧伤损伤来研究导致烧伤引起肌肉蛋白质分解增加的蛋白水解酶。在肌肉匀浆10000×g的沉淀中，烧伤刺激了蛋白酶活性（提高50%至100%），其最适pH值为3、5.5和7.8。烧伤还刺激了来自经Triton X100处理的肌肉提取物的27000×g上清液中的酸性蛋白酶活性。用化合物48/80预处理大鼠（以消除污染的肥大细胞）可消除颗粒部分中95%的中性蛋白酶活性。Ca++敏感的中性蛋白酶不受烧伤或48/80处理的影响。然而，烧伤腿部的肌肉提取物中酸性蛋白酶活性总是增加40%至70%。所有酸性蛋白酶活性都可被组织蛋白酶抑制剂胃蛋白酶抑制剂（0.01微克/毫升）和亮抑酶肽（1微摩尔/升）以及亮抑酶肽（1微摩尔/升）或Ep475（1微克/毫升）的组合所抑制。亮抑酶肽和溶酶体促渗剂亮氨酸甲酯也抑制完整肌肉中烧伤诱导的蛋白水解。时间进程显示全肌肉蛋白水解和肌肉匀浆酸性蛋白酶活性平行增加。这些发现支持以下结论：溶酶体组织蛋白酶的增加足以解释烧伤引起的受伤腿部肌肉蛋白质分解增加。
