Hydroxamic acids, biosynthesis

Further evidence that the hydroxamic-acid containing compounds represent a more highly evolved type of siderochrome is given by inspection of their mode of biosynthesis which, in every case that has been critically examined, requires molecular oxygen (68, 79). 

Desai, R. S., Kumar, P. and Chilton, W. S. 1996. Indole is an intermediate in the biosynthesis of cyclic hydroxamic acids in maize. Chem. Commun., 1321... 

Growth of Fusariutn sp. at low iron concentration causes the accumulation of a variety of hydroxamic acids of which one has been characterized and named fusarinine, or NS-( s-5-hydroxy-3-methylpent-2-enoyl)-NS-hydroxy-L-ornithine (38). The cis configuration in the unsaturated acyl substituent accounts for the extreme acid lability of the hydroxamic acid bond. Fusarinine is the amino acid unit, bearing the hydroxamic acid linkage, present in ferrirhodin. The characterization of fusarinine has important implications for the biosynthesis of the ferrichrome group for it indicates that the hydroxamic acid bond is inserted at the free amino, acid, rather than at the peptide level. 

H. Ohkawa, and H. Iwamura (2002). Molecular characterization and chromosomal localization of cytochrome P450 genes involved in the biosynthesis of cyclic hydroxamic acids in hexaploid wheat. Mol. Gen. Genet. 267, 210-217. 

LEIGHTON, V., NIEMEYER, H.M., JONSSON, L.M.V., Substrate specificity of a glucosyltransferase and a IV-hydroxylase involved in the biosynthesis of cyclic hydroxamic acids in Gramineae, Phytochemistry, 1994, 36, 887-892. 

Textor S, Bartram S, Kroymann J, Falk KL, Hick A, Pickett JA, Jonathan Gershenzon J (2004) Biosynthesis ofmethionine-derived glucosinolates in Arabidopsis thaliana recombinant expression and characterization of mefliylthioalkylmalate synthase, the condensing enzyme of the chain-elongation cycle. Planta 218 1026-1035 Thaler J S (1999) Jasmonate-inducible plant defences cause increased parasitism of herbivores. Nature 399 686-688 Thackaray DJ, Wratten SD, Edwards PJ, Niemeyer HM (1990) Resistance to the aphids Sitobion avenae and Rhopalosiphum padi in Gramineae in relation to hydroxamic acid levels. Ann Appl Biol 116 573-582... 

Figure 10.12 Biosynthesis and transformation of benzoxazinoid hydroxamic acids.

Leucine is known to be a precursor of neoaspergillic acid and pulcherriminic acid, and MacDonald s results would seem to rule out a role of the N-hydroxyamino acids as intermediates in the biosynthesis of these hydroxamates, although direct experiments using the hydroxylamino acids as substrates would be desirable. In the aspergillic acid family, it thus appears that the amino acid nitrogen undergoes substitution by carbon prior to its oxidation (oxygenation ). 

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