Supriya Ghosh (Editor)

Tris

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Molar mass
  
121.14 g/mol

Density
  
1.328 g/cm³

Melting point
  
175 °C

Formula
  
C4H11NO3

Boiling point
  
219 °C

Soluble in
  
Water

Tris

Appearance
  
White crystalline powder

IUPAC ID
  
2-Amino-2-hydroxymethyl-propane-1,3-diol

Tris


Tris, or tris(hydroxymethyl)aminomethane, or THAM, is an organic compound with the formula (HOCH2)3CNH2. It 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.

Contents

Buffering features

Tris has a pKa 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 pKa 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 by the exhaustive condensation of nitromethane with formaldehyde under basic conditions (i.e. repeated nitroaldol reactions) to produce the intermediate (HOCH2)3CNO2, which is subsequently hydrogenated to give the final product.

    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.

    References

    Tris Wikipedia
    (Text) CC BY-SA