Tris

This article is about the chemical widely used as a biochemical buffer. For other uses, see Tris (disambiguation).

Tris

Names
IUPAC name 2-Amino-2-hydroxymethyl-propane-1,3-diol
Other names TRIS, Tris, Tris base, Tris buffer, Trizma, Trisamine, THAM, Tromethamine, Trometamol, Tromethane, Trisaminol
Identifiers
CAS Number	77-86-1 Y
ChEBI	CHEBI:9754 Y
ChEMBL	ChEMBL1200391 N
ChemSpider	6257 Y
IUPHAR/BPS	7328
Jmol 3D model	Interactive image
KEGG	D00396 Y
PubChem	6503
RTECS number	TY2900000
UNII	023C2WHX2V Y
InChI InChI=1S/C4H11NO3/c5-4(1-6,2-7)3-8/h6-8H,1-3,5H2 Y Key: LENZDBCJOHFCAS-UHFFFAOYSA-N Y InChI=1/C4H11NO3/c5-4(1-6,2-7)3-8/h6-8H,1-3,5H2 Key: LENZDBCJOHFCAS-UHFFFAOYAN
SMILES OCC(N)(CO)CO
Properties
Chemical formula	C4H11NO3
Molar mass	121.14 g·mol−1
Appearance	White crystalline powder
Density	1.328g/cm3
Melting point	>175-176 °C (448-449 K)
Boiling point	219 °C (426 °F; 492 K)
Solubility in water	~50 g/100 mL (25 °C)
Acidity (pKa)	8.07
Pharmacology
ATC code	B05BB03 B05XX02
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Tris or Tris(hydroxymethyl)aminomethane or THAM is an organic compound 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 contains a primary amine and thus undergoes the reactions associated with typical amines, e.g. condensations with aldehydes.

Buffering features

Tris has a pK_a of 8.07 at 25 °C, which implies that the buffer has an effective pH range between 7.5 and 9.0.

Buffer details

• The pK_a declines approximately 0.03 units per degree Celsius rise in temperature.
• Silver-containing single-junction pH electrodes (e.g., silver chloride electrode) are incompatible with Tris (Ag-tris precipitation clogs the junction). Double-junction electrodes are resistant to this problem, and non-silver containing electrodes are immune.
• Making buffer solutions by neutralizing TrisHCl requires attention to the attendant changes in ionic strength.

Buffer inhibition

• Tris inhibits a number of enzymes, and therefore it should be used with care when studying proteins.

Preparation

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

Uses

The useful buffer range for tris (7-9) coincides with the physiological pH typical of most living organisms. This, and its low cost, make tris one of the most common buffers in the biology/biochemistry laboratory. Tris is also used as a primary standard to standardize acid solutions for chemical analysis.

Tris is used to increase membrane permeability of cell membranes.

Medical

Tris (usually known as THAM in this context) is used as alternative to sodium bicarbonate in the treatment of metabolic acidosis.

See also

• MOPS
• HEPES
• MES
• Common buffer compounds used in biology