Tris, or tris(hydroxymethyl)aminomethane, or known during medical use as tromethamine or THAM, is an
organic compound with the formula (HOCH2)3CNH2. It is extensively used in
biochemistry and
molecular biology as a component of
buffer solutions[2] such as in
TAE and
TBE buffers, 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. Tris also complexes with metal ions in solution.[3] In medicine, tromethamine is occasionally used as a drug, given in intensive care for its properties as a buffer for the treatment of severe
metabolic acidosis in specific circumstances.[4][5] Some medications are formulated as the "tromethamine salt" including
Hemabate (
carboprost as trometamol salt), and "
ketorolac trometamol".[6] In 2023 a strain of Pseudomonas hunanensis was found to be able to degrade TRIS buffer.[7]
Buffering features
The
conjugate acid of tris has a
pKa of 8.07 at 25 °C, which implies that the buffer has an effective
pH range between 7.1 and 9.1 (pKa ± 1) at room temperature.
Buffer details
In general, as temperature decreases from 25 °C to 5 °C the pH of a tris buffer will increase an average of 0.03 units per degree. As temperature rises from 25 °C to 37 °C, the pH of a tris buffer will decrease an average of 0.025 units per degree.[8]
In general, a 10-fold increase in tris buffer concentration will lead to a 0.05 unit increase in pH and vice versa.[8]
Silver-containing single-junction pH electrodes (e.g.,
silver chloride electrodes) are incompatible with tris since an Ag-tris precipitate forms which clogs the junction. Double-junction electrodes are resistant to this problem, and non-silver containing electrodes are immune.
Buffer inhibition
Tris inhibits a number of enzymes,[9][10] and therefore should be used with care when studying proteins.
Tris can also inhibit enzyme activity via
chelation of metal ions.[3]
Preparation
Tris is prepared industrially by the exhaustive condensation of
nitromethane with
formaldehyde under basic conditions (i.e. repeated
Henry reactions) to produce the intermediate (HOCH2)3CNO2, which is subsequently
hydrogenated to give the final product.[11]
Uses
The useful buffer range for tris (pH 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.
^Hoste, Eric A.; Colpaert, Kirsten; Vanholder, Raymond C.; Lameire, Norbert H.; De Waele, Jan J.; Blot, Stijn I.; Colardyn, Francis A. (May 2005). "Sodium bicarbonate versus THAM in ICU patients with mild metabolic acidosis". Journal of Nephrology. 18 (3): 303–307.
ISSN1121-8428.
PMID16013019.
^BNF 73 March-September 2017. British Medical Association,, Royal Pharmaceutical Society of Great Britain. London. 21 March 2017.
ISBN978-0857112767.
OCLC988086079.{{
cite book}}: CS1 maint: location missing publisher (
link) CS1 maint: others (
link)
^Ghalanbor, Z; et al. (2008). "Binding of tris to Bacillus licheniformis alpha-amylase can affect its starch hydrolysis activity". Protein Pept. Lett. 15 (2): 212–214.
doi:
10.2174/092986608783489616.
PMID18289113.
^Markofsky, Sheldon, B. (15 October 2011). "Nitro Compounds, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Vol. 24. p. 296.
doi:
10.1002/14356007.a17_401.pub2.
ISBN978-3527306732.{{
cite book}}: CS1 maint: multiple names: authors list (
link)
^Kallet, RH; Jasmer RM; Luce JM; et al. (2000). "The treatment of acidosis in acute lung injury with tris-hydroxymethyl aminomethane (THAM)". American Journal of Respiratory and Critical Care Medicine. 161 (4): 1149–1153.
doi:
10.1164/ajrccm.161.4.9906031.
PMID10764304.
^Hoste, EA; Colpaert, K; Vanholder, RC; Lameire, NH; De Waele, JJ; Blot, SI; Colardyn, FA (2005). "Sodium bicarbonate versus THAM in ICU patients with mild metabolic acidosis". Journal of Nephrology. 18 (3): 303–7.
PMID16013019.