English

TRIS

1. Transportation Research Information (see Transportation Research Board)

French

Noun

m|p

1. Plural of tri

Latin

Cardinal number

tris (accusative of tres)

1. three

this the chemical compound Tris is an abbreviation of the organic compound known as tris(hydroxymethyl)aminomethane, with the formula (HOCH2)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 nucleic acids. It is a primary amine and thus undergoes the reactions associated with typical amines, e.g. condensations with aldehydes.

Buffering features

Tris has a pKa of 8.3 (at 20 °C), which implies that the buffer has an effective pH range between 7.0 and 9.2. Being slightly basic, tris forms an effective buffer for slightly basic solutions, which keeps DNA deprotonated and soluble in water. Tris is commonly combined with EDTA to make "TE buffer" for stabilization and storage of DNA. EDTA binds to magnesium (Mg2+), which is a co-factor for many DNA-modifying enzymes. More importantly, however, EDTA has a stronger affinity for iron ions, which are often trace contaminants in magnesium, and which can react with DNA. Thus only a small amount of EDTA is typically added, most of which binds to magnesium and reduces the effective magnesium concentration, but it also functions to protect the DNA from being cut by iron.

Buffer details

Because of the widespread use of tris buffers, detailed information on its use is available. Some features:

• The pKa declines approximately 0.03 units per degree Celsius rise in temperature.
• Tris reacts strongly with pH electrodes.
• It is toxic to mammalian cells.

Preparation

Tris is prepared in two steps from nitromethane via the intermediate (HOCH2)3CNO2 . Reduction of the latter gives tris(hydroxymethyl)aminomethane.

Uses

Tris has been used in protein crystallization at various pH values. Low-ionic strength tris buffers in the formation of intermediate filaments of lamin from C. elegans has been described. The use of tris in both capillary electrochromatography and UV analysis of tocopherols and tocotrienols has been documented. Tris is also used as an intermediate for the preparation of surface active agents, vulcanization accelerators, and pharmaceuticals, and used as a titrimetric standard.

It is also used in SDS-PAGE

References