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Hence, pseudoprolines fulfill two functions simultaneously: they serve (1) as temporary side-chain protection for Ser, Thr, and Cys and (2) as solubilizing building blocks to increase solvation and coupling rates during peptide synthesis and in subsequent chain assembly. Pseudoprolines are obtained by reacting the free amino acids with ...
The sequence hypothesis was first formally proposed in the review "On Protein Synthesis" by Francis Crick in 1958. [1] It states that the sequence of bases in the genetic material (DNA or RNA) determines the sequence of amino acids for which that segment of nucleic acid codes, and this amino acid sequence determines the three-dimensional structure into which the protein folds.
At neutral pH, nucleic acids are highly charged as each phosphate group carries a negative charge. [7] Both DNA and RNA are built from nucleoside phosphates, also known as mononucleotide monomers, which are thermodynamically less likely to combine than amino acids. Phosphodiester bonds, when hydrolyzed, release a considerable amount of free energy.
These chains are linear and unbranched, with each amino acid residue within the chain attached to two neighboring amino acids. In nature, the process of making proteins encoded by RNA genetic material is called translation and involves the step-by-step addition of amino acids to a growing protein chain by a ribozyme that is called a ribosome. [58]
From the DNA double helix model, it was clear that there must be some correspondence between the linear sequences of nucleotides in DNA molecules to the linear sequences of amino acids in proteins. The details of how sequences of DNA instruct cells to make specific proteins was worked out by molecular biologists during the period from 1953 to 1965.
Two categories of macromolecules in particular are the focus of the molecular biologist: 1) nucleic acids, among which the most famous is deoxyribonucleic acid (or DNA), the constituent of genes, and 2) proteins, which are the active agents of living organisms. One definition of the scope of molecular biology therefore is to characterize the ...
Synthetic nucleotides can be used to expand the genetic alphabet and allow specific modification of DNA sites. Even just a third base pair would expand the number of amino acids that can be encoded by DNA from the existing 20 amino acids to a possible 172. [8] Hachimoji DNA is built from eight nucleotide letters, forming four possible base ...
The primary structure of a biopolymer is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry).For a typical unbranched, un-crosslinked biopolymer (such as a molecule of a typical intracellular protein, or of DNA or RNA), the primary structure is equivalent to specifying the sequence of its monomeric subunits, such as amino ...