Tildon J T, Roeder L M
J Neurosci Res. 1980;5(1):7-17. doi: 10.1002/jnr.490050103.
The oxidation of [1,3-14C] glycerol to 14CO was measured in slices, whole homogenates, and subcellular fractions of rat brain. In all of these tissue preparations, the Lineweaver-Burk plots of glycerol oxidation were biphasic, yielding two apparent Km and V values. Similar kinetic characteristics were obtained with brain homogenates from guinea pig, mouse, rabbit, monkey, and pig. In other tissues of the rat, including heart, kidney, liver, and skeletal muscle, the Lineweaver-Burk plots for glycerol oxidation were not biphasic but were linear. Heating the brain homogenates for five minutes at 5 degrees C caused a 50% decrease in the rate of oxidation of glycerol without a change in the biphasic double reciprocal plot. The addition of purified glycerol kinase (EC 2.7.1.30) to the homogenate caused an increase in the rate of oxidation and resulted in linear Lineweaver-Burke plot. Brain mitochondria were prepared by two different methods, both of which yielded an enrichment of glycerol oxidation. In contrast, the rate of glucose oxidation was higher in homogenates than in mitochondria, and glucose competed with glycerol as substrate only extramitochondrially. The effects of various metabolic inhibitors suggested the participation of intact, coupled mitochondria, of glycolytic enzymes, and of electron transport in the oxidation of glycerol. The data support the primary localization of glycerol oxidation in nonsynaptic mitochondria in brain and the presence in that organelle of enzymes of the Embden-Meyerhoff pathway or an as yet unidentified system for oxidizing this compound.
在大鼠脑的切片、全匀浆和亚细胞组分中测定了[1,3 - 14C]甘油氧化为14CO的情况。在所有这些组织制剂中，甘油氧化的Lineweaver - Burk图呈双相，产生两个表观Km和V值。用豚鼠、小鼠、兔、猴和猪的脑匀浆也获得了类似的动力学特征。在大鼠的其他组织中，包括心脏、肾脏、肝脏和骨骼肌，甘油氧化的Lineweaver - Burk图不是双相的，而是线性的。将脑匀浆在5℃加热5分钟导致甘油氧化速率降低50%，而双相双倒数图没有变化。向匀浆中添加纯化的甘油激酶（EC 2.7.1.30）导致氧化速率增加，并产生线性的Lineweaver - Burke图。通过两种不同方法制备脑线粒体，两种方法都使甘油氧化增加。相比之下，匀浆中葡萄糖氧化速率高于线粒体，并且葡萄糖仅在线粒体外作为底物与甘油竞争。各种代谢抑制剂的作用表明完整的、偶联的线粒体、糖酵解酶和电子传递参与了甘油的氧化。这些数据支持甘油氧化主要定位于脑的非突触线粒体中，并且在该细胞器中存在Embden - Meyerhoff途径的酶或尚未鉴定的氧化该化合物的系统。
