Biochemistry
6th Edition
ISBN: 9781305577206
Author: Reginald H. Garrett, Charles M. Grisham
Publisher: Cengage Learning
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Chapter 25, Problem 16P
A Deficiency on 3-Phosphogtycerate Dehydrogenase Can Affect Amino Acid
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The clinical symptoms of two forms of galactosemia—deficiency of galactokinase or of UDPglucose: galactose 1-phosphate uridylyltransferase—show radically different severity. Although both types produce gastric discomfort after milk ingestion, deficiency of the transferase also leads to liver, kidney, spleen, and brain dysfunction and eventual death. What products accumulate in the blood and tissues with each type of enzyme deficiency? Estimate the relative toxicities of these products from the above information.
Phosphoglycerate mutase (PGM) catalyzes the interconversion of 3-phosphoglycerate (3PG) and 2-phosphoglycerate (2PG) in the glycolytic and gluconeogenic pathways.
a) To what enzyme class does PGM belong?
b) There are two distinct classes of PGM, one which is dependent on 2,3-bisphosphoglycerate (2,3-BPG), dPGM, and one which is not, iPGM. dPGM uses acid base chemistry and a phosphorylated histidine residue to interconvert 3PG and 2PG. The dPGM reaction proceeds with formation of 2,3-BPG as an intermediate. Propose a mechanism for the dPGM-catalyzed conversion of 3PG to 2PG that is consistent with this information.
c) What is the purpose of 2,3-BPG (i.e., why does dPGM require it)?
The clinical signs of two types of galactosemia—galactokinase deficiency or UDPglucose: galactose 1-phosphate uridylyltransferase deficiency—are markedly different. Although both forms cause gastrointestinal pain after drinking milk, transferase deficiency also causes liver, kidney, spleen, and brain malfunction, as well as mortality. With each kind of enzyme shortage, what products accumulate in the blood and tissues? Estimate the relative toxicity of these goods based on the information provided above.
Chapter 25 Solutions
Biochemistry
Ch. 25 - Prob. 1PCh. 25 - Prob. 2PCh. 25 - Regulation of Glutamine Synthetase by Covalent...Ch. 25 - The Energetic Cost of Nitrogen Excretion via the...Ch. 25 - Prob. 5PCh. 25 - Prob. 6PCh. 25 - Prob. 7PCh. 25 - Prob. 8PCh. 25 - Prob. 9PCh. 25 - Prob. 10P
Ch. 25 - Prob. 11PCh. 25 - Prob. 12PCh. 25 - Prob. 13PCh. 25 - Prob. 14PCh. 25 - Prob. 15PCh. 25 - A Deficiency on 3-Phosphogtycerate Dehydrogenase...Ch. 25 - Prob. 17PCh. 25 - Prob. 18PCh. 25 - Prob. 19PCh. 25 - Consider the synthesis and degradation of tyrosine...Ch. 25 - Prob. 21PCh. 25 - Prob. 22P
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