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Amino acids have zero mobility in electrophoresis at their isoelectric point, although this behaviour is more usually exploited for peptides and proteins than single amino acids. Zwitterions have minimum solubility at their isoelectric point, and some amino acids (in particular, with nonpolar side chains) can be isolated by precipitation from ...
Isoelectric point. The isoelectric point (pI, pH (I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH (I). [1] However, pI is also used. [2] For brevity, this article uses pI.
Isoionic point. The isoionic point is the pH value at which a zwitterion molecule has an equal number of positive and negative charges and no adherent ionic species. It was first defined by S.P.L. Sørensen, Kaj Ulrik Linderstrøm-Lang and Ellen Lund in 1926 [1] and is mainly a term used in protein sciences. It is different from the isoelectric ...
Mineral acids, such as hydrochloric and sulfuric acid are used as precipitants. The greatest disadvantage to isoelectric point precipitation is the irreversible denaturation caused by the mineral acids. For this reason isoelectric point precipitation is most often used to precipitate contaminant proteins, rather than the target protein.
Isoelectric focusing (IEF), also known as electrofocusing, is a technique for separating different molecules by differences in their isoelectric point (pI). [1][2] It is a type of zone electrophoresis usually performed on proteins in a gel that takes advantage of the fact that overall charge on the molecule of interest is a function of the pH ...
The isoelectric point of albumin is 4.7. [8] Alpha-fetoprotein is a fetal plasma protein that binds various cations, fatty acids and bilirubin. Vitamin D-binding protein binds to vitamin D and its metabolites, as well as to fatty acids. Not much is known about afamin. It seems to carry lipidated Wnt proteins and Vitamin E around. [9]
Serine (symbol Ser or S) [3][4] is an α- amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − NH+. 3 form under biological conditions), a carboxyl group (which is in the deprotonated − COO−. form under biological conditions), and a side chain consisting of a hydroxymethyl ...
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. D-aspartic acid is one of two D-amino acids commonly found in mammals.