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The pH-dependence of the activity displayed by enzymes and the pH-dependence of protein stability, for example, are properties that are determined by the pK a values of amino acid side chains. The pK a values of an amino acid side chain in solution is typically inferred from the pK a values of model compounds (compounds that are similar to the ...
If the pH drops, some amino acids in the polypeptide chain can become protonated if the pka of their R groups is higher than the new pH. Protonation can change the charge these R groups have. If the pH raises, some amino acids in the chain can become deprotonated (if the pka of the R group is lower than the new pH). This also changes the R ...
Phosphorylation introduces a charged and hydrophilic group in the side chain of amino acids, possibly changing a protein's structure by altering interactions with nearby amino acids. Some proteins such as p53 contain multiple phosphorylation sites, facilitating complex, multi-level regulation. Because of the ease with which proteins can be ...
Backbone-dependent rotamer library for serine.Each plot shows the population of the χ 1 rotamers of serine as a function of the backbone dihedral angles φ and ψ. In biochemistry, a backbone-dependent rotamer library provides the frequencies, mean dihedral angles, and standard deviations of the discrete conformations (known as rotamers) of the amino acid side chains in proteins as a function ...
In the reaction from arginine to citrulline, one of the terminal nitrogen atoms of the arginine side chain is replaced by an oxygen. Thus, arginine's positive charge (at physiological pH) is removed, altering the protein's tertiary structure. The reaction uses one water molecule and yields ammonia as a side-product:
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from sequences of amino acids, which are the monomers of the polymer. A single amino acid monomer may also be called a residue, which indicates a
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.
Adenylylation, [1] [2] more commonly known as AMPylation, is a process in which an adenosine monophosphate (AMP) molecule is covalently attached to the amino acid side chain of a protein. [3] This covalent addition of AMP to a hydroxyl side chain of the protein is a post-translational modification . [ 4 ]