1电子传递。2质子的输送。.ppt

The mitochondria of brown fat have a unique protein in their inner membrane. Thermogenin, also called the uncoupleing protein, provides a path for protons to return to the matrix without passing through the FoF1 complex. 因為棕色脂肪粒線體膜上具有獨特的蛋白Thermogenin又稱uncoupleing protein，會破壞質子梯度。 Heat generation by uncoupled mitochondria Mitochondrial P-450 oxygenases catalyze steroid hydroxylations Mitochondria are the site of biosynthetic reaction that produce steroid hormones, including the sex hormones, glucocorticoids, mineralocorticoids, and vitamin D hormone. 粒線體是合成類固醇與維生素D的胞器。 These hormones are synthesized from cholesterol or a related sterol in a series of hydroxylations catalyzed by the enzymes of the cytochrome P-450 family.這些荷爾蒙是由膽固醇經一系的羥化反應而成，而催化這些反應的酵素為cytochrome P-450 家族的成員。 In the hydroxylation reactions, one atom of molecular oxygen is incorporated into the substrate and the second is reduced to H2O: R-H + O2 + NADPH → R-OH + H2O + NADP+ 羥化反應的方程式如上。 Mitochondrial P-450 oxygenases catalyze steroid hydroxylations Cytochrome P-450 enzymes are situated in the inner mitochondrial membrane with their catalytic site exposed to the matrix. All of P-450 enzyme have a critical heme group. Its absorption at 450 nm gives this family its name。 Cytochrome P-450酵素位於粒線體內膜，其催化的位置曝露於基質中。具有血質(heme), 因對450奈米具有強的吸收故名之。 The path of electron flow in the mitochondrial P-450 system is involved a flavoprotein and an iron-sulfur protein that carry electrons from NADPH to the P-450 heme. P-450系統的電子流動路徑包含黃素蛋白、硫鐵蛋白與NADPH。 Mitochondria of adrenal gland, specialized for steroid synthesis Path of electron flow in mitochondrial cytochrome P-450 reactions in adrenal gland Another large family of P-450 enzymes Found in the ER of hepatocytes.另一大族群則位內質網，催化反應類似於粒線體的P-450 enzymes。主要用於解毒代謝。 Catalyze reactions similar to the mitochondrial P-450 reactions. Their substrates include a wide variety of hydrophobic compounds, many of which are xenobiotics－compounds not found in nature but synthesized i