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Food Interactions, Sirtuins, Genes, Homeostasis, and General Discussion
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Cellular RNAs range in length from less than 100 to many thousands of nucleotides. Cellular DNA molecules can be as long as several hundred million nucleotides (107). The DNA molecule is a long, coiled, double helix that resembles a spiral staircase. In DNA, two strands, composed of sugar (deoxyribose) and phosphate molecules, are connected by pairs of four molecules called bases, which form the steps of the staircase (106). In the steps, adenine is paired with thymine and guanine is paired with cytosine. In DNA, hydrogen bonds between the base portions of the nucleotides hold the two chains together like rungs of a ladder. A gene consists of a sequence of bases. Sequences of three bases code for an amino acid (amino acids are the building blocks of proteins) (106).
Nucleic Acids as Therapeutic Targets and Agents
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
Unlike methylating agents that add a relatively small methyl group to bases in the major groove of DNA, alkylating agents covalently attach bulkier molecular fragments, usually in the minor groove. The only commercialized example of an alkylating agent at the time of writing is trabectedin (YondelisTM), which adds a bulky group of over 760 Da to guanines in the DNA minor groove. This causes significant distortion of the helix and invokes DNA repair. Although still at the experimental stage, the pyrrolobenzodiazepine (PBD) monomer and dimer families of agents are also mentioned in this section and in Section 5.3.10 (Sequence-Selective Cross-Linking Agents) because they lead to covalent attachment of bulky molecular fragments of approximately 300 Da and 600 Da, respectively, by alkylating or cross-linking in the DNA minor groove. Agents of this type are being developed as cytotoxic payloads for Antibody-Drug Conjugates (ADCs), and are further described in Chapter 7.
Genetics
Published in Cathy Laver-Bradbury, Margaret J.J. Thompson, Christopher Gale, Christine M. Hooper, Child and Adolescent Mental Health, 2021
Deoxyribonucleic acid (DNA) is located in the nucleus and mitochondria of the cell. It consists of a sugar-phosphate backbone and four different types of nitrogenous base: adenine, cytosine, thymine and guanine. Each base partner with a complementary base to form base pairs. The DNA molecule itself forms a double helix structure, which is tightly coiled. Nuclear DNA contains approximately 21,000 genes in humans and has been more extensively studied than mitochondrial DNA.
Congenital alacrima
Published in Orbit, 2022
Zhenyang Zhao, Richard C. Allen
HELIX syndrome is a newly defined disorder characterized by hypohidrosis, electrolyte imbalance, lacrimal gland dysfunction, ichthyosis and xerostomia.34 It is caused by biallelic mutations (autosomal recessive) in CLDN10, which encodes claudin-10, an integral membrane protein essential in the formation of the tight junction plates to maintain cell polarity. Localization of claudin-10 is found along the apical and basolateral membrane in the acinar cells of the exocrine glands, including the salivary and lacrimal glands.65 The mechanistic link between a CLDN10 mutation and alacrima remains elusive but is proposed to be a consequence of losing sodium transport across the tight junction.34 Heat intolerance and alacrima are the earliest signs in these patients and are universally observed in published cases.33,34 Detailed ophthalmic evaluation and description in HELIX patients has yet to be reported.
CALR-ETdb, the database of calreticulin variants diversity in essential thrombocythemia
Published in Platelets, 2022
Nora El Jahrani, Gabriel Cretin, Alexandre G. de Brevern
The selected proteins have been realigned with proper alignment tool as PSI-BLAST, dedicated to mining, did not provide excellent alignment. For the type 1, the A chain of the Sulfolobus tododaii carboxyl transferase (PDB id: 1X0U chain A) was selected as it had 29.0% sequence identity and a covering of 73.3%. Its structure formed a helix-loop structure. For the type 2, three identical proteins emerged (PDB ids 2B5U chain A, 1JCH chain A, and 5EW5 chain A). Finally, the chain A of the mutant colicin E3 protein V206 C (PDB id 2B5U chain A) was selected; it had a sequence identity of 24.7% with a coverage of 70.0%. This protein, compared to the two others, had no missing residues and the region of interest was mainly helical. It can be noticed that the chain A of the translocation domain of the ColE7 protein (PDB id 2AXC) was also obtained with a percentage identity of 39.0%, but with a relatively low coverage of 40.0%, and therefore has not been selected.
Understanding physical mechanism of low-level microwave radiation effect
Published in International Journal of Radiation Biology, 2018
Hiie Hinrikus, Maie Bachmann, Jaanus Lass
Hydrogen bonds are responsible for many of the properties of water and for holding together the DNA double helix. Hydrogen bond can be intermolecular (e.g. bonding between water molecules) as well as intramolecular (e.g. bonding in protein and DNA). Hydrogen bonds are major factors determining the water’s viscosity, boiling temperature and other properties (Petrucci et al. 2007). Hydrogen bonds contribute to the overall stability of the DNA double helix structure and the structure of proteins (Silberberg 2012). The spectrum of hydrogen bonds includes the frequencies up to MW and infrared band (Shiraga et al. 2017). The energies associated with hydrogen bonds are about 2–12 kT (Watson 1965; Van der Spoel et al. 2006). Hydrogen bonds have about a tenth of the strength of an average covalent bond. Although these hydrogen bonding intermolecular attractive forces are rather weak, the consolidated power of the huge amount of hydrogen bonds in DNA provides the stability of a molecule (Silberberg 2012). Hydrogen bonds are being constantly broken and reformed in liquid water as a result of random thermal motion of molecules despite the bonding energy is higher kT (Petrucci et al. 2007).