1.0 0.5 8-05 -0.5 (^_^) 607 -1.0 -1.5 ADP Pi +Cq²+ ADP Ρί -00-00 Дарь +Cq²+ Pi -C02+ 2+ -2.0 -1.0 о Log [x-KG] (mM) 1.0 2. (a) ( In contrast to the pyruvate dehydrogen- ase complex, the a-ketoglutarate dehydrogenase (aKGDH) complex is not up- or downregulated by phosphorylation or dephosphorylation. However, the complex exhibits cooperativity modulated by the presence of ADP, ATP, inorganic phosphate (Pi), and Ca2+, as illustrated by the diagram on the right for the bovine kidney enzyme complex. Note in the diagram how the addition of 10 μM Ca2+ shifts the affinity of the enzyme complex for aKG from 20 mM Pi/-Ca2+ to 20 mM Pi/+Ca2+. Calcium especially en- hances the cooperative influence of ADP and ATP. Using the expanded copy of the diagram at the end of the problem set, estimate the change in S0.5 (re- member that for allosteric enzymes S0.5 corresponds to KM of a nonallosteric enzyme) for the enzyme complex in the presence of 20 mM Pi/-Ca2+ and in the presence of 20 mM Pi/+Ca2+. Compare similarly the change in S0.5 for the enzyme in the presence of 20 mM Pi/-Ca2+ plus 1.6 mM ADP to the enzyme in the presence of 20 mM Pi/+Ca²+ plus 1.6 mM ADP. By what factor has the affinity of the aKGDH enzyme for the substrate been increased in each case? Does the aKGDH complex exhibit positive or negative co- operativity? (수) 607 1.0 0.5 8-05 -1.0 -1.5 ADP Pi +Cq²+ ADP Pl -Cα 2+ Pi +Cq²+ 000 Деревер a sadassssss Pi -002+ -2.0 -1.0 о Log [α-KG] (mM) 1.0
1.0 0.5 8-05 -0.5 (^_^) 607 -1.0 -1.5 ADP Pi +Cq²+ ADP Ρί -00-00 Дарь +Cq²+ Pi -C02+ 2+ -2.0 -1.0 о Log [x-KG] (mM) 1.0 2. (a) ( In contrast to the pyruvate dehydrogen- ase complex, the a-ketoglutarate dehydrogenase (aKGDH) complex is not up- or downregulated by phosphorylation or dephosphorylation. However, the complex exhibits cooperativity modulated by the presence of ADP, ATP, inorganic phosphate (Pi), and Ca2+, as illustrated by the diagram on the right for the bovine kidney enzyme complex. Note in the diagram how the addition of 10 μM Ca2+ shifts the affinity of the enzyme complex for aKG from 20 mM Pi/-Ca2+ to 20 mM Pi/+Ca2+. Calcium especially en- hances the cooperative influence of ADP and ATP. Using the expanded copy of the diagram at the end of the problem set, estimate the change in S0.5 (re- member that for allosteric enzymes S0.5 corresponds to KM of a nonallosteric enzyme) for the enzyme complex in the presence of 20 mM Pi/-Ca2+ and in the presence of 20 mM Pi/+Ca2+. Compare similarly the change in S0.5 for the enzyme in the presence of 20 mM Pi/-Ca2+ plus 1.6 mM ADP to the enzyme in the presence of 20 mM Pi/+Ca²+ plus 1.6 mM ADP. By what factor has the affinity of the aKGDH enzyme for the substrate been increased in each case? Does the aKGDH complex exhibit positive or negative co- operativity? (수) 607 1.0 0.5 8-05 -1.0 -1.5 ADP Pi +Cq²+ ADP Pl -Cα 2+ Pi +Cq²+ 000 Деревер a sadassssss Pi -002+ -2.0 -1.0 о Log [α-KG] (mM) 1.0
Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
Section: Chapter Questions
Problem 1P
Related questions
Question
![1.0
0.5
8-05
-0.5
(^_^) 607
-1.0
-1.5
ADP
Pi
+Cq²+
ADP
Ρί
-00-00
Дарь
+Cq²+
Pi
-C02+
2+
-2.0
-1.0
о
Log [x-KG] (mM)
1.0](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F7e3218aa-1b65-42a2-9071-7edb43c3a555%2F65af5d38-15cb-44cb-88bf-f0fbc0321005%2Fn4ou19y7_processed.png&w=3840&q=75)
Transcribed Image Text:1.0
0.5
8-05
-0.5
(^_^) 607
-1.0
-1.5
ADP
Pi
+Cq²+
ADP
Ρί
-00-00
Дарь
+Cq²+
Pi
-C02+
2+
-2.0
-1.0
о
Log [x-KG] (mM)
1.0
![2. (a) ( In contrast to the pyruvate dehydrogen-
ase complex, the a-ketoglutarate dehydrogenase
(aKGDH) complex is not up- or downregulated by
phosphorylation or dephosphorylation. However, the
complex exhibits cooperativity modulated by the
presence of ADP, ATP, inorganic phosphate (Pi),
and Ca2+, as illustrated by the diagram on the right
for the bovine kidney enzyme complex. Note in the
diagram how the addition of 10 μM Ca2+ shifts the
affinity of the enzyme complex for aKG from 20 mM
Pi/-Ca2+ to 20 mM Pi/+Ca2+. Calcium especially en-
hances the cooperative influence of ADP and ATP.
Using the expanded copy of the diagram at the end
of the problem set, estimate the change in S0.5 (re-
member that for allosteric enzymes S0.5 corresponds
to KM of a nonallosteric enzyme) for the enzyme
complex in the presence of 20 mM Pi/-Ca2+ and in
the presence of 20 mM Pi/+Ca2+. Compare similarly
the change in S0.5 for the enzyme in the presence of
20 mM Pi/-Ca2+ plus 1.6 mM ADP to the enzyme in
the presence of 20 mM Pi/+Ca²+ plus 1.6 mM ADP.
By what factor has the affinity of the aKGDH enzyme
for the substrate been increased in each case? Does
the aKGDH complex exhibit positive or negative co-
operativity?
(수) 607
1.0
0.5
8-05
-1.0
-1.5
ADP
Pi
+Cq²+
ADP
Pl
-Cα
2+
Pi
+Cq²+
000
Деревер
a sadassssss
Pi
-002+
-2.0
-1.0
о
Log [α-KG] (mM)
1.0](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F7e3218aa-1b65-42a2-9071-7edb43c3a555%2F65af5d38-15cb-44cb-88bf-f0fbc0321005%2Fn1jxld_processed.png&w=3840&q=75)
Transcribed Image Text:2. (a) ( In contrast to the pyruvate dehydrogen-
ase complex, the a-ketoglutarate dehydrogenase
(aKGDH) complex is not up- or downregulated by
phosphorylation or dephosphorylation. However, the
complex exhibits cooperativity modulated by the
presence of ADP, ATP, inorganic phosphate (Pi),
and Ca2+, as illustrated by the diagram on the right
for the bovine kidney enzyme complex. Note in the
diagram how the addition of 10 μM Ca2+ shifts the
affinity of the enzyme complex for aKG from 20 mM
Pi/-Ca2+ to 20 mM Pi/+Ca2+. Calcium especially en-
hances the cooperative influence of ADP and ATP.
Using the expanded copy of the diagram at the end
of the problem set, estimate the change in S0.5 (re-
member that for allosteric enzymes S0.5 corresponds
to KM of a nonallosteric enzyme) for the enzyme
complex in the presence of 20 mM Pi/-Ca2+ and in
the presence of 20 mM Pi/+Ca2+. Compare similarly
the change in S0.5 for the enzyme in the presence of
20 mM Pi/-Ca2+ plus 1.6 mM ADP to the enzyme in
the presence of 20 mM Pi/+Ca²+ plus 1.6 mM ADP.
By what factor has the affinity of the aKGDH enzyme
for the substrate been increased in each case? Does
the aKGDH complex exhibit positive or negative co-
operativity?
(수) 607
1.0
0.5
8-05
-1.0
-1.5
ADP
Pi
+Cq²+
ADP
Pl
-Cα
2+
Pi
+Cq²+
000
Деревер
a sadassssss
Pi
-002+
-2.0
-1.0
о
Log [α-KG] (mM)
1.0
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