Linked Life Data

7826328

Source:http://linkedlifedata.com/resource/pubmed/id/7826328

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1995-2-16
pubmed:abstractText
The extracellular siderophore from Mycobacterium smegmatis, exochelin MS, was isolated from iron-deficiently grown cultures and purified to > 98% by a combination of ion-exchange chromatography and h.p.l.c. The material is unextractable into organic solvents, is basic (pI = 9.3-9.5), has a lambda max at 420 nm and a probable Ks for Fe3+ of between 10(25) and 10(30). Its structure has been determined by examination of desferri- and ferri-exochelin and its gallium complex. The methods used were electrospray-m.s. and one- and two-dimensional (NOESY, DQF-COSY and TOCSY) 1H n.m.r. The constituent amino acids were examined by chiral g.l.c analysis of N-trifluoroacetyl isopropyl and N-pentafluoropropionyl methyl esters after hydrolysis, and reductive HI hydrolysis, of the siderophore. The exochelin is a formylated pentapeptide: N-(delta-N-formyl,delta N-hydroxy-R-ornithyl) -beta-alaninyl-delta N-hydroxy-R-ornithinyl-R-allo-threoninyl-delta N-hydroxy-S-ornithine. The linkages involving the three ornithine residues are via their delta N(OH) and alpha-CO groups leaving three free alpha-NH2 groups. Although there are two peptide bonds, these involve the three R (D)-amino acids. Thus the molecule has no conventional peptide bond, and this suggests that it will be resistant to peptidase hydrolysis. The co-ordination centre with Fe3+ is hexadenate in an octahedral structure involving the three hydroxamic acid groups. Molecular modelling shows it to have similar features to other ferric trihydroxamate siderophores whose three-dimensional structures have been established. The molecule is shown to have little flexibility around the iron chelation centre, although the terminal (Orn-3) residue, which is not involved in iron binding except at its delta N atom, has more motional freedom.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-1107222, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-2202378, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-240908, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-2714285, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-2942636, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-2968361, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-3141575, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-3309144, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-430028, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-4425672, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-4652567, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-4918634, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-6826517, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-6989958, http://linkedlifedata.com/resource/pubmed/commentcorrection/7826328-7689374
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0264-6021
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
305 ( Pt 1)
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
187-96
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Isolation, purification and structure of exochelin MS, the extracellular siderophore from Mycobacterium smegmatis.
pubmed:affiliation
Department of Chemistry, Cambridge University, U.K.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't