5. (a) key cellular metabolites – including precursors for nucleic acids and modulators of cellular red/ox bal- ance – via the oxidative phase of the pentose phosphate pathway. What nucleic acid precursor mole- cule and what key cofactor are generated by the oxidative phase of the pentose phosphate pathway? Draw the reactions including all reactants and products that comprise this phase of the pathway. In addition to consumption by glycolysis, glucose 6-phosphate is used to generate other

5. (a) key cellular metabolites – including precursors for nucleic acids and modulators of cellular red/ox bal- ance – via the oxidative phase of the pentose phosphate pathway. What nucleic acid precursor mole- cule and what key cofactor are generated by the oxidative phase of the pentose phosphate pathway? Draw the reactions including all reactants and products that comprise this phase of the pathway. In addition to consumption by glycolysis, glucose 6-phosphate is used to generate other

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter18: Glycolysis

Section: Chapter Questions

Problem 6P: The Reactions and Meehanisms of the Leloir Pathway Write the reactions that permit galactose to be...

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In the hexokinase reaction (in glycolysis) Keq caclualtion, what is the OBVIOUS problem with getting a Keq of 678? what should keq be normally? how can you EXPLAIN a Keq of 678?
In the first step of the aldolase reaction, an active site Lys229 residue, with its side chain amino group in the deprotonated state, acts as a nucleophile and attacks the carbonyl C2 carbon of fructose 1,6-bisphosphate to form a Schiff base (boxed in the scheme). Since the pKa of the Lys side chain amino group in free solution is ~10.5, the pKa of Lys229 side chain must have been perturbed to a (higher lower) value for the enzyme to be active at neutral pH. the answer should include sufficient details, including the definition of pKa.
One of the examples that we have used to illustrate the concept of equilibrium is the isomerization of glucose-6-phosphate (G6P) to fructose-6-phosphate (F6P), which is the second step in g ycolysis. Draw a graph to show how the reaction Gibbs energy varies with the fraction fof F6P in solution.Label the regions of the graph that correspond to the formation of F6P and G6P being spontaneous, respectively.
The active site of an enzyme that uses a general acid-base catalytic mechanism contains a Glu and an Asp residue (both of which are essential for catalysis) with pKa values of 5.9 and 4.5, respectively. If the enzyme is found in the lysosome (pH = 5.2), which residue will act as the general acid and which will act as the general base during the initial steps of the reaction?
In 1937, two German biochemists published a paper proposing these reactions as part of glucose oxidation: citrate → isocitrate → α-ketoglutarate →succinate → fumarate → malate → oxaloacetate. Adding succinate, fumarate, or malate to thin slices of tissue increased oxygen consumption, supporting the hypothesis that these molecules are intermediates in the process. However, they were puzzled by the observation that these intermediates were still present in the reaction mixture at the end of the experiment. They had thought that intermediates would be consumed as they were converted to the next molecule in the pathway. What explains the observation that these intermediates were still present? a) The pathway is a cycle, constantly regenerating intermediates as glucose is broken down. b) Succinate, fumarate, and malate are not reactants but catalysts, and catalysts are not consumed in the process. c) Succinate, fumarate, and malate increase metabolism and therefore oxygen consumption,…
How many tritium atoms (3H) are incorporated into myristate when fatty acid synthesis is carried out in vitro with the following labeled substrate?
The M and H subunits of lactate dehydrogenase have very similar sizes and shapes but differ in amino acidcomposition. If the only difference between the two were that theH subunit had a glutamic acid in a position where the M subunithad a serine, how would the five isozymes of LDH separate on electrophoresis using a gel at pH 8.6?
In Bacillus subtilis, threonine is metabolized by the following sequence of reactions: (a) oxidation; (b) decarboxylation;(c) transamination; and (d) oxidation to produce pyruvate. Outline this sequence of steps, show the structures of thesubstances, use abbreviations for the cofactors, and show any enzyme-bound coenzymes. What type of enzyme bound intermediate is likely for reaction (d)?
The turnover number of the enzyme fumarase that catalyzes the reaction, Fumarate + H20 ===→ L-malate, is 2.5 x 103 S - l and Km = 4.0 X 10- 6 mol/L. Calculate the rate of conversion of fumarate to L-malate if the fumarase concentration is 1.0 x 1 0 - 6 mol/L and the fumarate concentration is 2.04 x 10- 4 mol/L.
What if the phosphate group for the glycolysis reaction with enzyme glyceraldehyde 3-phosphate dehydrogenase was from ATP instead of Pi? What would the complete, balanced, net rxn of glycoslysisequation be and how does this impact the overall glycolysis rxn?
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