PENTOSE PHOSPHATE (PHOSPHOGLUCONATE) PATHWAY Student Edition
5/30/13 VERSION
Dr. Brad Chazotte 213 Maddox Hall
[email protected] Web Site:
http://www.campbell.edu/faculty/chazotte Original material only ©2000-14 B. Chazotte
Pharm. 304 Biochemistry Fall 2014
Goals • Learn the Pentose Phosphate Pathway and its oxidative and non-oxidative phases. • Learn what the Pentose phosphate pathway produces and how it can react to various metabolic demands (pathway modes of operation) • Be familiar with the pathways that require pathway products. • Understand the role of the transketolase and transaldolase reactions.
Pentose Phosphate Reaction Overall
3 Glucose-6-P + 6 NADP+ + 3 H2O 6 NADPH + 6 H+ + 3CO2 + 2F-6-P + GAP
Stage 1
3G-6-P + 6 NADP+ + 3 H2O 6 NADPH + 6 H+ + 3CO2
Stage 2
3Ru5P R5P + 2 Xu5P
Stage 3
R5P + 2Xu5P 2F6P + GAP
Voet & Voet 1995 Chap 21 p. 617-9
Pathways That Require NADPH Two key functions: 1. It provides all organisms with a source of NADPH to use on reductive biosynthesis 2. Generates pentose sugars, particularly ribose
Berg, Tymoczko, & Stryer 2012 Table 20.4
PENTOSE PHOSPHATE PATHWAY Oxidative Phase
Nonoxidative
Berg, Tymoczko, & Stryer 2002 Fig 20.19
Voet, Voet, & Pratt 2013 Figure 15.30
Pentose Phosphate Pathway
Berg, Tymoczko, & Stryer 2012 Table 20.3
Pentose Phosphate Pathway: Oxidative Phase
Berg, Tymoczko, & Stryer 2012 Fig 20.19
Pentose Phosphate Pathway: Oxidative Phase Rx 1
Voet, Voet, & Pratt 2013 Chap 15 p.508
Glucose 6-P Dehydrogenase Rx (#1)
6-Phosphogluconate Dehydrogenase Rx (#3)
Voet & Voet Biochemistry 1995 Fig. 21.24
Pentose Monophosphate Pathway
Voet, Voet & Pratt 2013 Figure 15.31
Pentose Phosphate Pathway: Oxidative Phase Rx 2
Berg, Tymoscko, & Stryer 2002 Fig 20.20b
Pentose Phosphate Pathway: Oxidative Phase Rx 3
Berg, Tymoscko, & Stryer 2012 Fig 20.19c
Linking the Pentose Phosphate and Glycolytic Pathways [Transketolase & Transaldolase Rxs]
Linking the Pentose Pathway and Glycolysis Transketolase C5 + C5
C3 + C7 Transaldolase
C3 + C7
C6 + C4 Transketolase
C4 + C5
C6 + C3 Net Reaction
3 C5
2 C6 + C3
Berg, Tymoczko, & Stryer 2012 Chap 20
Nonoxidative Reactions of the Pentose Phosphate Pathway.
Lehninger 2000 Fig 15.21a
Schematic: 6 Pentoses to 5 Hexoses
Lehninger 2000 Fig 15.21b
Pentose Phosphate Pathway: Transketolase Rx
Berg, Tymoczko, & Stryer 2012 Chao. 20 p. 603
Pentose Phosphate Pathway: Transaldolase Rx
Berg, Tymoczko, & Stryer 2012 Chao. 20 p. 603
Pentose Phosphate Pathway: Transketolase Rx II
Berg, Tymoczko, & Stryer 2012 Chao. 20 p. 603
Transketolase & Transaldolase Mechanisms
Carbanion Intermediates
Berg, Tymoscko, & Stryer 2002 Fig 20.23
Pentose Phosphate Pathway: Transketolase Mechanism
Ketose Substrate
Ketose Product
Aldose Product
Aldose Substrate
Voet, Voet & Pratt 2013 Fig 15.32
Pentose Phosphate Pathway: Transaldolase Mechanism Aldose Product Ketose Substrate
Ketose Product
Aldose Substrate
Voet, Voet & Pratt 2013 Fig 15.33
Pentose Phosphate Pathway
Berg, Tymoczko, & Stryer 2012 Table 20.3
Glycolytic & Pentose Phosphate Pathways Relationships
Voet, Voet & Pratt 2013 Figure 15.34
Four Modes of the Pentose Phosphate Pathway
Mode 1: Mode 2: Sum of Mode 3: Mode 4:
5 glucose-6-P + ATP 6 ribose-5-P + ADP + H+ glucose-6-P + 2NADP+ + H2O ribose-5-P + 2NADPH + 2H+ +CO2 glucose-6-P + 12NADP+ +7 H2O 6 CO2 + 12NADPH + 12H+ +Pi 3 glucose-6-P + 6 NADP+ + 5 NAD+ + 5Pi + 8 ADP 5 pyruvate + 3 CO2 + 6 NADPH = 5 NADH + 8 ATP + 8H+ +2H2O
Berg, Tymoscko, & Stryer 2002 Fig 20.24
Tissues with P.P. Pathway
Berg, Tymoczko, & Stryer 2012 Table 20.4
End of Lectures
