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Thiophene is considered to be aromatic, although theoretical calculations suggest that the degree of aromaticity is less than that of benzene. The "electron pairs" on sulfur are significantly delocalized in the pi electron system. As a consequence of its aromaticity, thiophene does not exhibit the properties seen for conventional sulfides. For ...
The continuous chain of protons are the sidechain of the individual amino acids. Thus these two experiments are used to build so called spin systems, that is build a list of resonances of the chemical shift of the peptide proton, the alpha protons and all the protons from each residue ’s sidechain.
Aromatic amino acids, excepting histidine, absorb ultraviolet light above and beyond 250 nm and will fluoresce under these conditions. This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. [1] [2] Most proteins absorb at 280 nm due to the presence of tyrosine and ...
Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.
A phylogenetic tree showing how a number of monoamine receptors are related to each other. Monoamine neurotransmitter systems occur in virtually all vertebrates, where the evolvability of these systems has served to promote the adaptability of vertebrate species to different environments.
Protein sequence is typically notated as a string of letters, listing the amino acids starting at the amino-terminal end through to the carboxyl-terminal end. Either a three letter code or single letter code can be used to represent the 22 naturally encoded amino acids, as well as mixtures or ambiguous amino acids (similar to nucleic acid ...
Glucose can exist in both a straight-chain and ring form. Two specific further subcategories of tautomerizations: Annular tautomerism is a type of prototropic tautomerism wherein a proton can occupy two or more positions of the heterocyclic systems found in many drugs, for example, 1 H - and 3 H - imidazole ; 1 H -, 2 H - and 4 H - 1,2,4 ...
The side chains of the standard amino acids have a variety of chemical structures and properties, and it is the combined effect of all amino acids that determines its three-dimensional structure and chemical reactivity. [35] The amino acids in a polypeptide chain are linked by peptide bonds between amino and carboxyl