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FDPB-based methods calculate the change in the pK a value of an amino acid side chain when that side chain is moved from a hypothetical fully solvated state to its position in the protein. To perform such a calculation, one needs theoretical methods that can calculate the effect of the protein interior on a pK a value, and knowledge of the pKa ...
Aspartic acid ball and stick model spinning. Aspartic acid (symbol Asp or D; [4] the ionic form is known as aspartate), is an α-amino acid that is used in the biosynthesis of proteins. [5] The L-isomer of aspartic acid is one of the 22 proteinogenic amino acids, i.e., the building blocks of proteins.
Although these are the most common, other residues with ionizable side chains such as histidine, tyrosine, and serine can also participate, depending on outside factors perturbing their pK a 's. The distance between the residues participating in the salt bridge is also cited as being important. The N-O distance required is less than 4 Å (400 pm).
It consists of three amino acid residues (labeled i, i+1 and i+2) in which residue i is an aspartate (Asp) or asparagine (Asn) that forms a hydrogen bond from its sidechain CO group to the mainchain NH group of residue i+2. About 14% of Asx residues present in proteins belong to Asx turns.
Amino acid Short Abbrev. Side chain Hydro-phobic pKa § Polar pH Small Tiny Aromatic or Aliphatic van der Waals volume (Å 3) Alanine: A Ala -CH 3 - - Aliphatic 67 Cysteine: C Cys -CH 2 SH: 8.55 acidic - 86 Aspartic acid: D Asp -CH 2 COOH 3.67 acidic - 91 Glutamic acid: E Glu -CH 2 CH 2 COOH 4.25 acidic - 109 Phenylalanine: F Phe -CH 2 C 6 H 5 ...
Asparagine also provides key sites for N-linked glycosylation, modification of the protein chain with the addition of carbohydrate chains. Typically, a carbohydrate tree can solely be added to an asparagine residue if the latter is flanked on the C side by X- serine or X- threonine , where X is any amino acid with the exception of proline .
Also, amino acid side chain affinity for water was measured using vapor phases. [14] Vapor phases represent the simplest non polar phases, because it has no interaction with the solute. [ 18 ] The hydration potential and its correlation to the appearance of amino acids on the surface of proteins was studied by Wolfenden.
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