Methylations in living cells are methyl groups attached to amino acids, DNA, RNA, and so on. However, their biochemical roles have not been fully defined. A theory has been postulated that methylation leads to hyperconjugation, and the electron-donating feature weakens a nearby chemical bond, which increases the bond length of C 4 −N 4 of 5-methylcytosine, therefore weakening the C 4 −N 4 bond and resulting in stronger protonation or hydrogen bonding of the N 4 nitrogen atom. Protonation can give rise to the generation of mutagenic and carcinogenic strong acids such as HCl, which are also capable of solubilizing stressful, insoluble, and stiff salts. Insoluble and rigid salts such as calcium oxalate and/or calcium phosphate were recently proposed as a primary cause of some neurodegenerative disorders. Protonation of nitrogen atoms in 5-methylcytosine enhances the interaction with negatively charged phosphate groups and contributes to the formation of compact heterochromatin. The electronegativity of the oxygen atoms in the modifications of 5-hydroxymethylcytosine or 5-formylcytosine can shorten the lengths of adjacent bonds with no increase of cation affinity in N 4 . The carboxyl group in 5-carboxylcytosine is a weak acid capable of antagonizing mutagenic HCl and modestly helping solubilize insoluble salts. Electron delocalization of the methyl group in N4methylcytosine results in a lower affinity of N 4 to cations. The positive charge at N 3 in the resonance structure of 3-methylcytosine is lessened by the electron-donating attribute of the methyl group attached to the N 3 atom, consequently reducing acid formation. The electron delocalization of three methyl groups decreases the positive charge in the amino nitrogen in the side group of lysine 4 in histone H3, weakening interactions with phosphate groups and consequently activating gene expression. The carbonyl oxygen in 8oxo-7,8-dihydroguanine draws protons and accumulates HCl, accounting for its moderate mutation propensity and potential capacity to solubilize stiff salts. The biochemical insight will further our understanding on the crosstalk of genetics and epigenetics in the etiology of neurodegenerative diseases.

The article published by Nie et al. addressed one of the two key questions regarding the Omicron variant of SARS-CoV-2, while the underpinning for the less deadly nature of the variant remains unexplained. The proteins of the Omicron variant have numerous mutations, notably several substitutions of other amino acids by lysine residues. Glycine and valine attract calcium and enhance the formation of stressful, insoluble, and stiff calcium oxalate. Lysine residues in proteins build up [a

Antagonism between hydrogen bonding and secondary chemical bonding to calcium in virusesWe read the article by Durstenfeld et al. [1] with great interest. The authors have raised a profound yet unanswered question in biology: why do some viruses tend to reinforce each other in virulence, while others show little mutual enhancement of adverse effect? ORCID: Qiuyun Liu https://orcid.org/0000-0001-5533-0128.

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