- Hydroxamic acid
A hydroxamic acid is a class of
chemical compound s sharing the samefunctional group in which anamine is inserted into ancarboxylic acid . Its general structure is R-CO-NH-OH, with an R as an organic residue, a CO as acarbonyl group, and ahydroxylamine as NH2-OH. They are used as metalchelator s.Hydroxamic acids can be synthesized from aldehydes via the
Angeli-Rimini reaction . A well-known hydroxamic acid reaction is theLossen rearrangement .Hydroxamates are essential growth factors, or vitamins, for some microbes. They function as iron-binding compounds (siderophores) that solubilise iron and transport it into the cell.
Iron is a key component of cytochromes and iron-sulphur proteins (involved in electron transport) and is thus important in cellular respiration. In an environment, absent from oxygen (anoxic); iron will be present in the ferrous +2 oxidation state (Fe2+), which is water-soluble. Under oxic conditions; iron will be in the ferric +3 oxidation state (Fe3+), in insoluble mineral form. The powerful chelating properties of hydroxamic acid and its derivatives is exploited by bacteria to obtain ferric iron. Once the iron-hydroxamate complex has entered the cell, the iron is liberated and the hydroxamic acid can be excreted and reused for iron transport.
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