What is the stable form of cytosine?
At the highest level of theory (method D in Table 1), the enol form with the hydroxyl hydrogen trans to N3 (tautomer C2t) is the most stable tautomer of cytosine, followed by the N1-H keto-amino (C1) and the cis enol (C2c) tautomers, which are around 0.8 kcal/mol less stable.
What is the tautomeric form of a base?
Nucleic acid bases can exist in multiple tautomeric forms due to the presence of solvent-exchangeable protons. Tautomers are structural isomers that differ from one another based on the position of proton(s) and double bonds (Antonov 2014).
What are tautomeric structures?
Tautomerism is a phenomenon where a single chemical compound tends to exist in two or more interconvertible structures that are different in terms of the relative position of one atomic nucleus which is generally the hydrogen.
Which tautomeric form of thymine is present in DNA?
Rare tautomeric state of T 3 * thymine and structural analysis of pairing of thymine T 3 * with canonical DNA bases Note: (a) thymine (Т) and adenine (А) are in canonical tautomeric forms; (b) rare tautomeric forms of thymine T 3 * and adenine A 3 *; (c) -(f) structural analysis of pairing of thymine T 3 * with …
What type of base is cytosine?
Cytosine (C) is one of four chemical bases in DNA, the other three being adenine (A), guanine (G), and thymine (T). Within the DNA molecule, cytosine bases located on one strand form chemical bonds with guanine bases on the opposite strand.
What is a tautomeric shift?
The spontaneous isomerization of a nitrogen base to an alternative hydrogen-bonding form, possibly resulting in a mutation. Reversible shifts of proton position in a molecule. bases in nucleic acids shift between keto and enol forms or between amino and imino forms.
How do you identify tautomers?
Tautomerism. Tautomers are isomers of a compound which differ only in the position of the protons and electrons. The carbon skeleton of the compound is unchanged. A reaction which involves simple proton transfer in an intramolecular fashion is called a tautomerism.
How do you make tautomers?
Keto Tautomer → Enol Tautomer In the first step, the carbonyl oxygen is protonated by an acid to form an intermediate oxonium compound. A base removes an α-hydrogen during the second step forming a double bond by an E2 type reaction.
What are tautomers give example?
Tautomers are constitutional isomers of two compounds that readily interconvert between one another. One of the most common examples of tautomers are the isomers of phenol. In tautomerization, the atoms in a molecule will rearrange themselves to form a different structure.
What is tautomeric mutation?
A tautomeric shift in one strand has produced a transition mutation in the complementary strand. If the mutation occurs in the germline, it will be transmitted to future generations. IMPORTANT: Note that a tautomeric shift is not itself a mutation, but a transient change to an alternative form of the molecule.
What is cytosine structure?
What is the composition of cytosine?
Cytosine is a pyrimidine nucleobase with a chemical formula of C4H5N3O. Pyrimidine is a heterocyclic aromatic organic compound with a single ring (called a pyrimidine ring) with alternating carbon and nitrogen atoms.
Is cytosine a tautomer?
Tautomerism of the cytosine molecule is discussed in connection with recent experimental matrix-isolation infrared spectroscopic measurements and recent ab initio calculations of relative stabilities of tautomers and of IR spectra for different tautomeric forms of the compound.
What are tautomers of adenine cytosine guanine thymine and uracil?
Tautomers of Adenine, Cytosine, Guanine, and Thymine. The four bases of DNA can exist in at least two tautomeric forms as shown below. Adenine and cytosine (which are cyclic amidines) can exist in either. amino or imino forms, and guanine, thymine, and uracil (which are cyclic amides) can exist in either lactam (keto) or lactim (enol) forms.
Are guanine-cytosine base pairs tautomeric?
Studies on tautomeric forms of Guanine-Cytosine base pairs of nucleic acids and their interactions with water molecules J Biomol Struct Dyn.
What are the four tautomeric forms of DNA?
The four bases of DNA can exist in at least two tautomeric forms as shown below. Adenine and cytosine (which are cyclic amidines) can exist in either amino or imino forms, and guanine, thymine, and uracil (which are cyclic amides) can exist in either lactam (keto) or lactim (enol) forms.