title: Inhibitory effect of the partially resolved coordination isomers of chromic desferricoprogen on coprogen uptake in Neurospora crassa.
abstract: Two partially resolved chromatographic fractions of geometrical and optical isomers of the chromic complexes of desferricoprogen, a siderophore from Neurospora crassa, were obtained from high-pressure liquid chromatography on a reverse-phase matrix. The first fraction was identified as a cis complex with a 20% diastereomeric excess of the lambda isomer. The second fraction was identified as a mixture of several of the possible trans isomers with a net 20% diastereomeric excess of the delta isomers. These fractions were used to evaluate the stereospecificity of the coprogen-mediated iron uptake system with respect to the metal coordination center. Fraction II competitively inhibited coprogen uptake, whereas fraction I showed only slight inhibition. N. crassa accumulated chromium from fraction II faster than the rate of chromium uptake from fraction I. Neither fraction had a significant effect on the uptake of ferricrocin, suggesting that coprogen and ferricrocin are taken up by different receptor systems.
mesh_terms: D002857:Chromium / Q000302:isolation & purification / Q000494:pharmacology*; D002942:Circular Dichroism; D054659:Diketopiperazines; D005291:Ferrichrome / Q000031:analogs & derivatives / Q000378:metabolism; D006877:Hydroxamic Acids / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000302:isolation & purification / Q000494:pharmacology*; D007504:Iron Radioisotopes; D009491:Neurospora / Q000378:metabolism*; D009492:Neurospora crassa / Q000378:metabolism*; D013237:Stereoisomerism
chemical_list: D054659:Diketopiperazines; D006877:Hydroxamic Acids; D007502:Iron Chelating Agents; D007504:Iron Radioisotopes; D002857:Chromium; D005291:Ferrichrome; C021678:ferricrocin; C010896:coprogen; C047664:desferricoprogen