Chemical Properties
White crystals
General Description
Colorless or off-white crystalline solid. pH (0.1 molar aqueous solution) 3.4. pH (0.2 molar aqueous solution) 3.2.
Reactivity Profile
A powerful reducing agent. Reacts with bases and oxidizing agents.
Air & Water Reactions
Hygroscopic. Sensitive to prolonged exposure to air. Water soluble. Reacts slowly with water.
Hazard
Toxic by ingestion, strong irritant to tissue.
Fire Hazard
Flash point data for this chemical are not available; however, HYDROXYLAMINE HYDROCHLORIDE is probably combustible.
Description
Hydroxylamine hydrochloride is a reducing agent that is routinely used for the deacetylation of SATA to form free sulfhydryls (Figure 1), for cleavage of protein cross‐linkers that contain carbonyl groups (i.e. EGS) and for mutagenesis of plasmid DNA.
Hydroxylamine converts aldehydes and ketones (carbonyls) to their oxime derivative in weak bases, therefore cross‐linkers and other compounds with carbonyl groups are cleavable with Hydroxylamine hydrochloride.
SATA and SATP are modification reagents that add a sulfhydryl group to primary amines on biomolecules. The initial modification results in the addition of an acetyl‐protected sulfur enabling storage of the biomolecule. To generate a free sulfhydryl the biomolecule is treated with hydroxylamine to remove the protecting acetyl group (see figure).
EGS and sulfo‐EGS are homobifunctional, succinimidyl ester, amine reactive crosslinkers that are resistant to cleavage by denaturants used in SDS‐PAGE conditions, but may be cleaved with hydroxylamine.
Physical properties
Colorless monoclinic crystals; hygroscopic; decomposes slowly in moist air;density 1.67 g/cm3at 17°C; melts at 151°C (decomposes); highly soluble inwater (84g/100g at 20°C); soluble in lower alcohols and glycols; pH of 0.1molar solution 3.4.
Definition
ChEBI: Hydroxylamine hydrochloride is an organic molecular entity. It is a colorless inorganic compound (HONH2) used in organic synthesis and as a reducing agent, due to its ability to donate nitric oxide.
Preparation
Hydroxylamine hydrochloride is prepared by electrolytic reduction ofammonium chloride.
Biotechnological Applications
Hydroxylamine hydrochloride(5470-11-1) is a strong reducing agent that is useful in biochemical crosslinking applications, including the deacetylation of SATA and chemical cleavage of EGS and Sulfo-EGS. Hydroxylamine converts carbonyl compounds (aldehydes and ketones) to their oxime derivatives in the presence of a weak base. Therefore, crosslinkers and other compounds that contain a carbonyl within their structure are cleavable with hydroxylamine?HCl.
EGS and its water-soluble analog, Sulfo-EGS, are homobifunctional, succinimidyl ester, amine-reactive crosslinkers useful for covalent stabilization of polypeptide multimers and protein:protein interactions. Unlike disulfidecontaining crosslinkers, EGS and Sulfo-EGS will not cleave by reducing SDS-PAGE conditions but may be cleaved when necessary with hydroxylamine.
SATA and SATP are modification reagents for addition of sulfhydryl groups to proteins and other molecules containing primary amines. Such sulfhydryl addition is an important step in one popular method for preparing protein conjugates such as antibodies with horseradish peroxidase enzyme. The initial modification results in addition of an acetyl-protected sulfur, enabling storage of the modified protein; to make the sulfur available as a sulhydryl group (-SH) for the final conjugation reaction, hydroxylamine is used to remove the protecting acetyl group.
Hydroxylamine?HCl is more stable to oxidation than the free base form of hydroxylamine; nevertheless, always prepare hydroxylamine solutions immediately before use and store the product desiccated. Hydroxylamine?HCl is soluble in polar solvents such as water, ethanol, methanol, glycerol and propylene glycol.
Flammability and Explosibility
Notclassified
Biochem/physiol Actions
MAO inhibitor; inhibits platelet aggregation.
Purification Methods
Crystallise the salt from aqueous75% ethanol or boiling methanol, and dry it under vacuum over CaSO4 or P2O5. It has also been dissolved in a minimum of water and saturated with HCl; after three such crystallisations, it is dried under a vacuum over CaCl2 and NaOH. Its solubility at 20o is 85% in H2O, 6% in EtOH and 12% in MeOH. [Hurd Inorg Synth I 87 1939, Semon in Org Synth Coll Vol I 318 1941.]
