Chapter 27. Nucleic Acids
Recommended Article: 【Organic Chemistry】 Organic Chemistry Table of Contents
1. Classification of Nucleotides
2. Adenine (A)
3. Guanine (G)
4. Thymine (T)
5. Cytosine (C)
6. Uracil (U)
a. Composition of Living Organisms
c. Nucleic Acid Extraction and Purification Experiment
1. Classification of Nucleotides
⑴ Classification by Ring Size
① Pyrimidine: A nucleotide with a base containing one ring. T, C, U.
② Purine: A nucleotide with a base containing two rings. A, G, I.
⑵ Classification by Functional Groups
① Amino Bases: Bases with only amino groups (-NH2). A, C.
② Keto Bases: Bases with ketone groups (C=O). T, G, U, I.
⑶ Symbols of Nucleotides
| Nucleotide Symbol | Full Name |
|---|---|
| A | Adenine |
| C | Cytosine |
| G | Guanine |
| T | Thymine |
| U | Uracil |
| R | Guanine / Adenine (Purine) |
| Y | Cytosine / Thymine (Pyrimidine) |
| K | Guanine / Thymine |
| M | Adenine / Cytosine |
| S | Guanine / Cytosine |
| W | Adenine / Thymine |
| B | Guanine / Thymine / Cytosine |
| D | Guanine / Adenine / Thymine |
| H | Adenine / Cytosine / Thymine |
| V | Guanine / Cytosine / Adenine |
| N | Adenine / Guanine / Cytosine / Thymine |
Table 1. Symbols of Nucleotides
2. Adenine (A)
Figure 1. Structure of Adenine
Figure 2. Structure of dAMP
3. Guanine (G)
Figure 3. Structure of Guanine
Figure 4. Structure of dGMP
4. Thymine (T)
Figure 5. Structure of Thymine
Figure 6. Structure of dTMP
5. Cytosine (C)
Figure 7. Structure of Cytosine
Figure 8. Structure of dCMP
6. Uracil (U)
Figure 9. Structure of Uracil
Figure 10. Structure of UMP
Not dUMP as it’s RNA
Figure 11. Pseudouridine and N1-methylpseudouridine
Modified nucleic acids used in producing recently popular mRNA drugs
Modified nucleic acids decrease immune response and increase protein production
7. Non-standard Nucleotides
⑴ Inosine
Figure 12. Inosine
① Product of ADAR-mediated RNA editing
② Prevalent in tRNA anticodon loops
③ Unique base pairing versatility
④ Insight into RNA energetics and function
○ Guanosine creates strong interactions that trap RNAs in slow-folding intermediates.
○ RNA chaperones resolve these traps by weakening guanosine contacts.
○ Inosine substitution shows that non-standard nucleotides can replicate this effect by tuning base-pair strength.
⑵ Pseudouridine
Figure 13. Pseudouridine
① Most prevalent RNA modification
② Isomer of uridine with altered connectivity
③ Stabilizes RNA structure and modulates function
④ Pseudouridine suppresses innate immune sensing, preventing inflammatory responses to synthetic mRNA.
⑤ In enhances mRNA stability and translation, enabling robust and sustained antigen expression.
⑥ This modification was essential for mRNA vaccine success, allowing rapid, safe COVID-19 vaccine development.
Input: 2019.03.12 17:30