Tris, or tris(hydroxymethyl)aminomethane, or known during medical use as tromethamine or THAM, is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
with the formula (HOCH
2)
3CNH
2, one of the twenty
Good's buffers
Good's buffers (also Good buffers) are twenty buffering agents for biochemical and biological research selected and described by Norman Good and colleagues during 1966–1980. Most of the buffers were new zwitterionic compounds prepared and tested ...
. It is extensively used in
biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
and
molecular biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...
as a component of
buffer solution
A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is ...
s such as in
TAE and
TBE buffer TBE or Tris/Borate/EDTA, is a buffer solution containing a mixture of Tris base, boric acid and EDTA.
In molecular biology, TBE and TAE buffers are often used in procedures involving nucleic acids, the most common being electrophoresis. Tris-acid ...
s, especially for solutions of
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...
s. It contains a
primary amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such a ...
and thus undergoes the reactions associated with typical amines, e.g. condensations with
aldehydes
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
. Tris also complexes with metal ions in solution.
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
Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...
in specific circumstances. Some medications are formulated as the "tromethamine salt" including
Hemabate
Carboprost ( INN, trade names for the tromethamine salts Hemabate, Tham) is a synthetic prostaglandin analogue of PGF2α (specifically, it is 15-methyl-PGF2α) with oxytocic properties.
Carboprost's main use is in the obstetrical emergency of p ...
(
carboprost
Carboprost (INN, trade names for the tromethamine salts Hemabate, Tham) is a synthetic prostaglandin analogue of PGF2α (specifically, it is 15-methyl-PGF2α) with oxytocic properties.
Carboprost's main use is in the obstetrical emergency of po ...
as trometamol salt), and "
ketorolac
Ketorolac, sold under the brand names Toradol, and Biorolac among others, is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain. Specifically it is recommended for moderate to severe pain. Recommended duration of treatment is less ...
trometamol".
Buffering features
The
conjugate acid
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...
of tris has a
p''K''a of 8.07 at 25 °C, which implies that the buffer has an effective
pH range between 7.1 and 9.1 (p''K''
a ± 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.
*In general, a 10-fold increase in tris buffer concentration will lead to a 0.05 unit increase in pH and vice versa.
*
Silver
Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
-containing single-junction pH electrodes (e.g.,
silver chloride electrode
A silver chloride electrode is a type of reference electrode, commonly used in electrochemical measurements. For environmental reasons it has widely replaced the saturated calomel electrode. For example, it is usually the internal reference elect ...
s) 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,
and therefore should be used with care when studying proteins.
*Tris can also inhibit enzyme activity via
chelation
Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a Denticity, polydentate (multiple bonded) ligand and a single central metal atom. These l ...
of metal ions.
Preparation
Tris is prepared industrially by the exhaustive condensation of
nitromethane
Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in ...
with
formaldehyde
Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...
under basic conditions (i.e. repeated
Henry reaction
The Henry reaction is a classic carbon–carbon bond formation reaction in organic chemistry. Discovered in 1895 by the Belgian chemist Louis Henry (1834–1913), it is the combination of a nitroalkane and an aldehyde or ketone in the presence ...
s) to produce the intermediate (HOCH
2)
3CNO
2, which is subsequently
hydrogenated
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic ...
to give the final product.
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 A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are ...
to standardize acid solutions for chemical analysis.
Tris is used to increase permeability of cell membranes. It is a component of the
Moderna COVID-19 vaccine
The Moderna COVID19 vaccine ( INN: elasomeran), sold under the brand name Spikevax, is a COVID-19 vaccine developed by American company Moderna, the United States National Institute of Allergy and Infectious Diseases (NIAID), and the Biomed ...
and the
Pfizer-BioNTech COVID-19 vaccine for use in children 5 through 11 years of age.
Medical
Tris (usually known as THAM in this context) is used as alternative to
sodium bicarbonate
Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation ( Na+) and a bicarbonate anion ( HCO3−) ...
in the treatment of
metabolic acidosis
Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys ...
.
See also
*
MOPS
MOPS (3-(''N''-morpholino)propanesulfonic acid) is a buffer introduced in the 1960s, one of the twenty Good's buffers. It is a structural analog to MES, and like MES, its structure contains a morpholine ring. HEPES is a similar pH buffering ...
*
HEPES
HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent; one of the twenty Good's buffers. HEPES is widely used in cell culture, largely because it is better at maintaining physiological pH de ...
*
MES
*
Common buffer compounds used in biology
References
{{reflist, 2
Polyols
Amines
Buffer solutions