(c) phorylated with ATP by action of triose kinase, is there a metabolic advantage for the mole-rat to rely only on metabolism of DHAP during the period of complete anoxia with respect to the total number of ATPS generated per fructose molecule via the KHK pathway. Write the pertinent reactions in which ATP is consumed or generated using words and naming enzymes and decide whether there is a metabolic advantage over the HK pathway. Although glyceraldehyde, generated as shown from fructose-1-phosphate, can be phos-

Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
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Chapter1: Biochemistry: An Evolving Science
Section: Chapter Questions
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It has been shown recently that the African naked
GLUT5-O Fructose
mole-rat can withstand up to 18 min of complete anoxia (ab-
sence of O2) in the presence of high levels of CO2 without ap-
parent brain damage. The basis of its capacity to tolerate such
unusual conditions is that the brain, heart, and liver in the mole-
rat switch to fructose-driven glycolysis. In contrast to normal
mice, these tissues in the naked mole-rat have high levels of
GLUT5 specific for cellular uptake of fructose. The available
pathways for breakdown of fruct
ose for metabolic energy production are shown on the right.
KHK stands for ketohexosekinase, an enzyme that is markedly
upregulated in the mole-rat compared to normal mice. Conse-
quently mice must metabolize fructose largely via hexokinase
(HK). In the diagram ALDOB, ALDOA, etc. represent aldolase
isozymes.
KHK
HK
Fructose-6-P
PFK
Fructose-1-P
Fructose-1,6-BP
ALDOB
ALDOC
ALDOA
ALDOC
Glyceraldehyde
DHAP
GAЗP
Glyc-3-P
3-PGA
Lactate
Pyruvate
mouse
naked mole-rat
Lactate
In the study, as seen in the graphs on the right for DHAP and
lactate production, it was shown with use of C-13 enriched
fructose that fructose-driven glycolysis in the mole-rat resulted
in faster conversion of fructose into glycolytic metabolites via
the KHK pathway than via the HK pathway in mice.
DHAP
1000007
8007
600-
60000-
400-
20000-
200-
30
15
Time (min)
5
15
30
Time (min)
(c)
phorylated with ATP by action of triose kinase, is there a metabolic advantage for the mole-rat to rely
only on metabolism of DHAP during the period of complete anoxia with respect to the total number of
ATPS generated per fructose molecule via the KHK pathway. Write the pertinent reactions in which
ATP is consumed or generated using words and naming enzymes and decide whether there is a
metabolic advantage over the HK pathway.
Although glyceraldehyde, generated as shown from fructose-1-phosphate, can be phos-
13C-labeled Quantity
(pmol/50mg tissue)
13C-labeled Quantity
(pmol/50mg tissue)
<-->
---->
Transcribed Image Text:It has been shown recently that the African naked GLUT5-O Fructose mole-rat can withstand up to 18 min of complete anoxia (ab- sence of O2) in the presence of high levels of CO2 without ap- parent brain damage. The basis of its capacity to tolerate such unusual conditions is that the brain, heart, and liver in the mole- rat switch to fructose-driven glycolysis. In contrast to normal mice, these tissues in the naked mole-rat have high levels of GLUT5 specific for cellular uptake of fructose. The available pathways for breakdown of fruct ose for metabolic energy production are shown on the right. KHK stands for ketohexosekinase, an enzyme that is markedly upregulated in the mole-rat compared to normal mice. Conse- quently mice must metabolize fructose largely via hexokinase (HK). In the diagram ALDOB, ALDOA, etc. represent aldolase isozymes. KHK HK Fructose-6-P PFK Fructose-1-P Fructose-1,6-BP ALDOB ALDOC ALDOA ALDOC Glyceraldehyde DHAP GAЗP Glyc-3-P 3-PGA Lactate Pyruvate mouse naked mole-rat Lactate In the study, as seen in the graphs on the right for DHAP and lactate production, it was shown with use of C-13 enriched fructose that fructose-driven glycolysis in the mole-rat resulted in faster conversion of fructose into glycolytic metabolites via the KHK pathway than via the HK pathway in mice. DHAP 1000007 8007 600- 60000- 400- 20000- 200- 30 15 Time (min) 5 15 30 Time (min) (c) phorylated with ATP by action of triose kinase, is there a metabolic advantage for the mole-rat to rely only on metabolism of DHAP during the period of complete anoxia with respect to the total number of ATPS generated per fructose molecule via the KHK pathway. Write the pertinent reactions in which ATP is consumed or generated using words and naming enzymes and decide whether there is a metabolic advantage over the HK pathway. Although glyceraldehyde, generated as shown from fructose-1-phosphate, can be phos- 13C-labeled Quantity (pmol/50mg tissue) 13C-labeled Quantity (pmol/50mg tissue) <--> ---->
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