N-Hydroxysuccinimide
Encyclopedia
N-Hydroxysuccinimide is a compound with a molecular weight of 115.09 and a melting point
of 95 °C
.
As it is slightly acidic, it is an irritant
to skin, eyes and mucous membrane
s.
It is commonly found in organic chemistry or biochemistry where it is used as an activating reagent for carboxylic acid
s. Activated acids (basically esters with a good leaving group
) can react with amine
s to form amide
s for example, whereas a normal carboxylic acid would just form a salt with an amine.
A common way to synthesize an NHS-activated acid is to mix NHS with the desired carboxylic acid and a small amount of an organic base in an anhydrous
solvent. A coupling reagent
such as dicyclohexylcarbodiimide
DCC or ethyl(dimethylaminopropyl) carbodiimide (EDC) is then added to form a highly unstable activated acid intermediate. NHS reacts to form a less labile activated acid. The group itself is usually written as SuO- or -OSu in chemical notation.
Such an ester with an acid and NHS, sometimes called succinate ester, is stable enough to be purified and stored at low temperatures in the absence of water and, as such, is commercially available. NHS esters are commonly used for protein
modification (e.g. an NHS ester of fluorescein
, are commercially available, and can be added to a protein to obtain a fluorescently labeled protein in one simple reaction and purification step).
Some alternatives to NHS are the water-soluble analog Sulfo-NHS, HOBt, HOAt and pentafluorophenol.
Melting point
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure...
of 95 °C
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
.
As it is slightly acidic, it is an irritant
Irritation
Irritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...
to skin, eyes and mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...
s.
It is commonly found in organic chemistry or biochemistry where it is used as an activating reagent for carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s. Activated acids (basically esters with a good leaving group
Leaving group
In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Leaving groups can be anions or neutral molecules. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters, such as para-toluenesulfonate...
) can react with amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s to form amide
Amide
In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...
s for example, whereas a normal carboxylic acid would just form a salt with an amine.
A common way to synthesize an NHS-activated acid is to mix NHS with the desired carboxylic acid and a small amount of an organic base in an anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
solvent. A coupling reagent
Peptide synthesis
In organic chemistry, peptide synthesis is the production of peptides, which are organic compounds in which multiple amino acids are linked via amide bonds which are also known as peptide bonds...
such as dicyclohexylcarbodiimide
Dicyclohexylcarbodiimide
N,N-Dicyclohexylcarbodiimide is an organic compound with chemical formula C13H22N2 whose primary use is to couple amino acids during artificial peptide synthesis. Under standard conditions, it exists in the form of white crystals with a heavy, sweet odor. The low melting point of this material...
DCC or ethyl(dimethylaminopropyl) carbodiimide (EDC) is then added to form a highly unstable activated acid intermediate. NHS reacts to form a less labile activated acid. The group itself is usually written as SuO- or -OSu in chemical notation.
Such an ester with an acid and NHS, sometimes called succinate ester, is stable enough to be purified and stored at low temperatures in the absence of water and, as such, is commercially available. NHS esters are commonly used for protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
modification (e.g. an NHS ester of fluorescein
Fluorescein
Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....
, are commercially available, and can be added to a protein to obtain a fluorescently labeled protein in one simple reaction and purification step).
Some alternatives to NHS are the water-soluble analog Sulfo-NHS, HOBt, HOAt and pentafluorophenol.