Case Files Biochemistry 3/E by Eugene Toy

Author:Eugene Toy
Language: eng
Format: epub
Publisher: McGraw-Hill Education
Published: 2015-11-18T16:00:00+00:00

APPROACH TO:

Glycolysis and the Malate-Aspartate Shuttle

OBJECTIVES

1. Be familiar with glycolysis.

2. Know the role of glycerol 3-phosphate and the malate-aspartate shuttle.

3. Be aware of the role of mitochondria in glycolysis.

DEFINITIONS

MYOCARDIAL INFARCTION: An area of heart muscle is inadequately perfused as a result of cardiac vessel occlusion resulting in ischemia, cell death, and loss of cell constituents including enzymes into the circulation. Electrocardiographic changes occur as a result of damaged heart tissue.

ANGINA: Transient disruption of adequate blood flow to a portion of heart muscle leading to pain and a temporary shift to anaerobic glycolysis producing pyruvate and lactate that are released into the circulation.

AEROBIC GLYCOLYSIS: Metabolism of glucose to pyruvate. Pyruvate in the presence of sufficient oxygen can be metabolized to CO2 via the tricarboxylic acid cycle in the mitochondrion-producing NADH and FADH2, which contribute electrons through the electron transfer chain to molecular oxygen producing H2O and ATP.

ANAEROBIC GLYCOLYSIS: Metabolism of glucose to lactate in the absence of sufficient oxygen. When oxygen is lacking, pyruvate is converted to lactate, and no further oxidative pathway is available.

ELECTRON SHUTTLES: Enzymatic processes whereby electrons from NADH can be transferred across the mitochondrial barrier. The glycerol 3-phosphate shuttle uses the reduction of dihydroxyacetone phosphate to glycerol 3-phosphate and reoxidation to transfer electrons from cytosolic NADH to coenzyme Q in the electron transport chain. The malate-aspartate shuttle uses malate and aspartate in a 2-member transfer exchange to transfer electrons from cytosolic NADH to mitochondrial NADH (Figures 27-1 and 27-2).

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