A-///-Glycerophosphates

Shuttle pathways for the transport of electrons across the inner mitochondrial membrane. A. Glycerophosphate shuttle. B. Malate-aspartate shuttle. 

In 1924, Martland et al. (1) reported on phosphatase activity in red blood cells. Roche later differentiated between the phosphatase of the red cells with pH optimum 6.0-6.2 and the phosphatase from white cells with optimum 8.8-9.0. Roche also showed that a-glycerophosphate was split more rapidly than -glycerophosphate by red cell extracts while the reverse was true of acid phosphatase activity in plasma (2). While studying the source of acid phosphatase activity in male urine, Kutscher and Wolberg discovered the very high activity of acid phosphatase in human prostate (3). This tissue was shown by Woodard to have one-thousand times the activity of extracts from bone, liver, and kidney (3a). Igarashi and Hollander crystallized the acid phosphatase of rat liver and showed that under certain conditions allosteric control of the activity could be demonstrated (4). 

Krebs and Woodford (72) have reported the activity of FDPase to be much lower than that of phosphofructokinase in muscle, but it has been estimated by Salas et al. (71) that in view of the relative mass of muscle tissue, the total FDPase activity of muscle was equivalent to that of liver. It was proposed by Krebs and Woodford (72) that the enzyme might play a role in the reconversion of a-glycerophosphate to carbohydrate since this substance was found to accumulate in significant quantities in muscle. This hypothesis has been examined in detail by... 

Ovalbumin Conalbumin Ovomucoid Lysozyme Vitellogenin apo-VLDL Glucose-6-P-dehydrogenase Oviduct Oviduct (liver) Oviduct Oviduct Liver Liver Uterus Thyroid Hormones Carbamyl phosphate synthase Growth hormone Prolactin ( ) a-Glycerophosphate dehydrogenase Malic enzyme Liver Pituitary Pituitary Liver (mitochondria) Liver... 

Evidence for the existence of an a-glycerophosphate oxidase system with three phosphorylation sites and sensitive to rotenone and piericidin A. FEBS Letters, 10 109-12. 

The plasmalogens represent an unusual type of glycerophosphatide that has been isolated from animal and plant tissues. Acid hydrolysis of these materials yields long-chain aldehydes and mono-acylated a-glycerophosphate. The long-chain aldehydes originate from vinyl ether structures. The vinyl ether group appears usually (if not always) in... 

X and Y are other ubiquinone-reducing flavoproteins (eg. from a glycerophosphate cr fatty acyl coenzyme A). 

The oxidation of L-glycerol 3-phosphate to dihydroxyacetone phosphate is catalyzed by two different enzymes. One is the cytoplasmic NAD-linked a-glycerophosphate dehydrogenase, and the other is the mitochondrial enzyme, which appears to contain flavin and iron. The latter enzyme was first studied by Green in 1936 (223). It was shown to be associated with respiratory particles, and widely distributed in animal tissues. The highest concentration of the enzyme was found in the brain. Lardy and co-workers (234) studied the enzyme in deoxycholate-solubilized particles obtained from skeletal muscle, confirmed the finding... 

Mitochondria from the flight muscle of house flies, Mtisca domestica, have been shown to oxidize a-glycerophosphate at exceptionally high rates (233, 234). This activity was shown to be inhibited by EDTA. It is believed that in these and other mitochondria the combined action of the soluble and the particle-bound a-glycerophosphate dehydrogenases... 

Fia. 37. The a-glycerophosphate cycle for the oxidation of extramitochondrial NADH by the mitochondrial respiratory chain. From Klingenberg (SS8). 

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