Draw a tautomer

(a) For each DNA base (A, T, G, and C), draw a tautomer that allows base pairing to occur with its normal partner. In other words, what are the tautomers of A and T that allow the A-T base pair to still form? What are the tautomeric forms of G and C that allow G-C base pairing? (b) Here is the introductory section to an excellent publication from 2001 (you can find it at this web address (https://pubs.acs.org/doi/pdf/10.1021/ja003647s) if you’re on a computer on campus: “Structural and dynamic properties of DNA base pairs are virtually always discussed in terms of the keto-amine tautomers, which are thought to be the dominant forms of the base pairs in duplex DNA. However, each base pair may be converted to its minor, but often reasonably stable enol- imine tautomer by a double proton transfer (prototropic tautomerism, Figure 1a). The presence of rare tautomers in DNA may be difficult to detect due to the fast time scale and minimal heavy atom motion, as well as the reversibility inherent to the proton-transfer reaction. Nonetheless, the rapid interbase proton transfer may contribute to the physical properties of DNA, including duplex flexibility, protein recognition, or fidelity during DNA replication, by providing a dipolar coupling between flanking base pairs.” How could the presence of one or more tautomers of DNA bases give rise to changes in “protein recognition” and “fidelity during DNA replication”? (Hints: “recognition” means binding, or intermolecular interactions, and cells can make mistakes in DNA replication if bases interact differently than the normal A-T and G-C pairings.) 5 . Shown here is the normal ” base pairing ” between nucleotides in DNA . These are the interactions that allow for geneticN – H .information to be stored and transferred in all living cells on earth . A = adenine , T = thymine , G = guanine , C = cytosine ; inITthese structures ” R ” is a cyclic sugar ( ribose ) that connects to phosphate linkages that wire the polymer together . The dottedred lines are hydrogen bonds , of course( a ) For each DNA base ( A , T , G , and C ) , write a tautomer that allows base pairing to occur with its normal partner. In othe words . what are the tautomers of A and I that allow the AT Rbase pair to still form ? What are the tautomeric forms of Gand C that allow G – C base pairing ?( b ) Here is the introductory section to an excellent publication from 2001 ( you can find it at thisweb address ( https / / pubs . acs . org doi / pdf / 10 . 1021 / 20036475 ) if you’re on a computer oncampusStructural and dynamic properties of DNA base pairs are virtually always discussed in terms ofhe keto – amine tautomers , which are thought to be the dominant forms of the base pairs in duplexDNA . However , each base pair may be converted to its minor , but often reasonably stable enolimine tautomer by & I double proton transfer ( prototropic tautomerism , Figure Ia ) . The presence ofrare tautomers in DNA may be difficult to detect due to the fast time scale and minimal heavy atommotion , as well as the reversibility inherent to the proton- transfer reaction . Nonetheless , the rapidinter base proton transfer may contribute to the physical properties of DNA , including duplex flexibility , protein recognition , or fidelity during DNA replication , by providing a dipolar coupling between flanking base pairs How could the presence of one or more tautomers of DNA bases give rise to changes in protein recognition ” and ” fidelity during DNA replication ” ? ( Hints : ” recognition ” mean binding , or intermolecular interactions , and cells can make mistakes in DNA replication if bases interact differently than the normal AT and G – C pairings . )