In chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, a NONOate is a compound having the chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 R¹R³N-(NO⁻)-N=O, where R¹ and R² are alkyl groups. One example for this is 1,1-diethyl-2-hydroxy-2-nitrosohydrazine, or diethylamine dinitric oxide. These compounds are unusual in having three sequential nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 atoms: an 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 Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group.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,...

 functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

, a bridging NO⁻ group, and a terminal nitrosyl group. In contact with water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

, these compounds release NO (nitric oxide

Nitric oxide

Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...

).

pH dependent decomposition of NONOates

Most NONOates are stable in alkaline solution above pH

PH

In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 8.0 (e. g. 10 mM NaOH) and can be stored at −20 °C in this way for the short term. To generate NO from NONOates, the pH is lowered accordingly. Typically, a dilution

Dilution

Dilution may refer to:* Reducing the concentration of a chemical* Serial dilution, a common way of going about this reduction of concentration* Homeopathic dilution* Dilution , an equation to calculate the rate a gas dilutes...

 of the stock NONOate solution is made in a phosphate

Phosphate

A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

 buffer (pH 7.4; Tris buffers

Tris

Tris is an abbreviation of the organic compound known as trisaminomethane, with the formula 3CNH2. Tris is extensively used in biochemistry and molecular biology. In biochemistry, tris is widely used as a component of buffer solutions, such as in TAE and TBE buffer, especially for solutions of...

 can also be used) and incubated at room temperature for the desired time to allow NO to accumulate in solution. This is often visible as bubbles at high NONOate concentration

Concentration

In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...

s. Incubation time is important since the different NONOates have different half-lives (t_½) in phosphate buffer at pH 7.4. For example, the half-life of MAHMA NONOate under these conditions is ~3.5 minutes, whilst the t_½ of DPTA NONOate is 300 minutes. This is often useful in biological systems where a combination of different NONOates can be used to give a sustained release of nitric oxide. At pH 5.0, most NONOates are considered to decompose

Chemical decomposition

Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...

almost instantaneously.