![Page 1: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/1.jpg)
Chem 454: Regulatory Mechanisms in BiochemistryUniversity of Wisconsin-Eau Claire
Lecture 12 - Nucleotide Biosynthesis
![Page 2: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/2.jpg)
2
TextNucleotides perform a wide variety of functions
Building blocks for nucleic acidsUniversal energy carriers (ATP, GTP)Activators (e.g. UDP-glucose)Components of signal transduction pathways (cAMP, cGMP)
Nucleotides containRibose or deoxyribose sugarOne to three phosphate groupspurine or pyrimidine hetercyclic nitrogen base.
Introduction
![Page 3: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/3.jpg)
3
TextWe will focus on the nucleotide bases
Glycine and aspartate will provide a carbon scaffold.
Aspartate and glutamine will provide the nitrogen.
We will look atde novo synthesis of pyrimidine bases
de novo synthesis of purines bases
Synthesis of deoxyribonucleotides
Regulation of nucleotide synthesis
Introductions
![Page 4: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/4.jpg)
4
Textde Novo versus salvage pathways
Introduction
![Page 5: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/5.jpg)
5
TextNomenclature
Introduction
![Page 6: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/6.jpg)
6
TextThe ring is assembled from bicarbonate, aspartate and glutamate.
The ring is synthesized first and then added to the ribose.
The ammonia is produced from the hydrolysis of glutamine
1. de Novo Synthesis of Pyrimidines
![Page 7: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/7.jpg)
7
TextCarbarmoyl phosphate is synthesized from bacarbonate and ammonia
1.1 Pyrimidine Synthesis, First Step
![Page 8: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/8.jpg)
8
TextCarbamoyl phosphate synthetate
1.1 Pyrimidine Synthesis, First Step
![Page 9: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/9.jpg)
9
TextCarbamoyl phosphate synthetase also contains a glutamine hydrolysis domain
1.2 Glutamine Hydrolysis
![Page 10: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/10.jpg)
10
TextThe ammonia is channeled 45Å to the carboxyphosphate
The carbamic acid is channeled another 35Å to the site where it is phosphorylated
1.3 Substrate Channeling
![Page 11: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/11.jpg)
11
TextSynthesis of Orotate and attachment to ribose ring.
The first reaction is catalyzed by aspartate transcarbamylase
1.4 Pyrimidine Synthesis, Second Step
![Page 12: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/12.jpg)
12
TextSynthesis of Orotate and attachment to ribose ring.
Reaction is driven by the hydorlysis of pyrophosphate
1.4 Pyrimidine Synthesis, Second Step
![Page 13: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/13.jpg)
13
TextDecarboxylation of orotidylate produces uridylate
1.4 Pyrimidine Synthesis, Second Step
![Page 14: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/14.jpg)
14
TextNucleotide mono-, di-, and triphospahtes are interconvertible
Nucleoside monophosphate kinasesUMP is converted to UTP before going on to produce CTP
1.5 Nucleotides
![Page 15: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/15.jpg)
15
TextCTP is formed by amination (not animation!) of UTP.
1.6 CTP
![Page 16: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/16.jpg)
16
TextSalvage versus de Novo synthesis
2. de Novo Synthesis of Purines
![Page 17: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/17.jpg)
17
TextThe purine ring system is assembled on a ribose phosphate.
glutamine phosphoribosyl amidotransferase
2.2 Purines Synthesis, Step One
![Page 18: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/18.jpg)
18
TextThe purine ring is assembled by successive steps of activation by phosphorylation, followed by displacement.
2.3 Purine Ring Synthesis
![Page 19: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/19.jpg)
19
Text
2.3 Purine Ring Synthesis
![Page 20: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/20.jpg)
20
Text
2.3 Purine Ring Synthesis
![Page 21: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/21.jpg)
21
TextAMP and GMP are formed from IMP
2.4 AMP and GMP
![Page 22: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/22.jpg)
22
TextDeoxyribonucleotides are produced form either ribonucleotide di- or triphophosphates
The 2'-OH on the ribose sugar is reduced to a hydrogen.
NADPH + H+ is the reducing agent.
The enzyme is called ribonucleotide reductase
3. Deoxyribonucleotides
![Page 23: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/23.jpg)
23
TextRibonucleotide reductase
R1 (87 kD dimer)active siteallosteric sites
R2 (43 kD dimer)
3. Deoxyribonucleotides
![Page 24: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/24.jpg)
24
TextRibonucleotide reductase: R1 subunit
3. Deoxyribonucleotides
![Page 25: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/25.jpg)
25
TextRibonucleotide reductase: R2 subunit
3. Deoxyribonucleotides
![Page 26: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/26.jpg)
26
TextRibonucleotide reductase
1. Transfer of a electron from a cysteine on R1 to the tyrosyl radical on R2
3. Deoxyribonucleotides
![Page 27: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/27.jpg)
27
TextRibonucleotide reductase
2. The cysteine thiyl radical produced on R1 abstracts a hydrogen from the C-3' of the ribose unit.
3. Deoxyribonucleotides
![Page 28: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/28.jpg)
28
TextRibonucleotide reductase
3. The carbon radical at C-3' promotes the release of a hydorxide ion on carbon-2.
3. Deoxyribonucleotides
![Page 29: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/29.jpg)
29
TextRibonucleotide reductase
4. Hydride is transfered from a third cysteine residue to complete the reduction of the C–2' position.
3. Deoxyribonucleotides
![Page 30: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/30.jpg)
30
TextRibonucleotide reductase
5. The C–3' radical recaptures the hydrogen that was abstracted by the first cysteine residue.
3. Deoxyribonucleotides
![Page 31: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/31.jpg)
31
TextRibonucleotide reductase
6. The tyrosyl free radical is regenerated
3. Deoxyribonucleotides
![Page 32: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/32.jpg)
32
TextRibonucleotide reductase
7. The disulfide is reduced by thioredoxin.8. Thioredoxin is reduced by thioredoxin reductase using NADH + H+
3. Deoxyribonucleotides
![Page 33: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/33.jpg)
33
Text
3.1 Thymidylated Formed by Methylation
![Page 34: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/34.jpg)
34
Text
3.2 Dihydrofolate Reductase
![Page 35: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/35.jpg)
35
Text
3.3 Anticancer Drugs
Inhibition of the synthesis of dexoyribonucleotides or thymidylate will selectively inhibit fast growing cells.
![Page 36: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/36.jpg)
36
Text
4. Regulation of Nucleotide Biosynthesis
![Page 37: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/37.jpg)
37
Text
5. NAD+, FAD and Coenzyme A (Skip)
![Page 38: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/38.jpg)
38
Text
6. Metabolic Diseases (Skip)
![Page 39: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/39.jpg)
39
Text
6.1 Purine Degradation (Skip)
![Page 40: Lecture 12 - Nucleotide Biosynthesis - University of Wisconsin-Eau](https://reader031.vdocuments.mx/reader031/viewer/2022020703/61fb46122e268c58cd5c393e/html5/thumbnails/40.jpg)
40
Text
6.2 Lesch-Nyhan Syndrome (Skip)