In the mammalian CNS there is a pyridoxal phosphate...

4. In the mammalian CNS there is a pyridoxal phosphate dependent glutamate decarboxylase that catalyzes the conversion of glutamate to gamma-amino butyric acid (GABA). This is an important inhibitory neurotransmitter. (see attachment) GABA is subsequently degraded through transamination to succinic semialdehyde, with alpha-ketoglutarate as the NH3+ acceptor: (see attachment) The succinic semialdehyde can then be oxidized to succinate, by succinate dehydrogenase. a. Show how these reactions can operate as a shunt pathway that allows the TCA cycle to function with alpha-ketoglutarate dehydrogenase and succinate thiokinase. b. Is the shunt more or less efficient than the TCA cycle in... click for more

In order to determine the major pathway of glycine degradation

In order to determine the major pathway of glycine degradation, you devise an experiment in which mice are fed 13C(alpha)-labeled glycine, and the livers are then isolated and radioactive intermediates detected by GC-MS. Interestingly, you find that the amino acid serine contains the most radioactivity, and that both the Calpha and Cbeta carbons of the serine residue are labeled with 13C. Explain these observations.

Oxidation of palmitate

Estimate the amount of energy a mammal can obtain from the oxidation of palmitate, in the liver under conditions of ketosis, relative to the amount obtainable under conditions of a balanced diet with adequate consumption of glucogenic fuels.

GRE subject question

Sugars in solution have the ability to rotate plane polarized light in proportions to their concentration. The specific rotation of a solution of a mixture of sugars is the weight average of the specific rotations of the individual components. The specific rotation , [α]20,D, for the α and β anomers of D-galactose 150.7˚ and 52.8˚ , respectively. Amixture of 5% α-D-galactose and 95% β-d-GALACTOSE IS DISSOLVED IN WATER AT 20˚C . A) What is the intial specific rotation of the solution? B) After several hours, the mixture reached an equilibrium value of 80.2 for the specific rotation. What is the equilibrium anomeric composition? C) What is the na... click for more

ATCase, CTP, ATP questions

1. In E. coli, ATCase is inhibited by CTP and is activated by ATP. Explain the biological significance of these effects. 2. Explain how PALA can act as both an activator and an inhibitor of ATCase.