Abstract
The ability of Neurospora crassa 2702—a xanthine dehydrogenase deficient mutant—to utilize chromium and copper complexes of uric acid (UA) has been examined. The complexes employed have been CrUA and Cr(UA)3 and a newly prepared copper complex, CuUA. Of these, the two chromium complexes but not CuUA were superior to free UA itself as sole N sources and as inducers of uricase. Also, the UA complexes of chromium but not copper were good substrates for N. crassa uricase.
The above features have been shown to be due to chromium UA complexes being transported as a result of a faster rate of uptake of UA into the mycelia. Interestingly, Cr3+ indicates that, intracellularly, chromium is handled quite differently under these two conditions. On the other hand CuUA was generally more toxic. These findings have been discussed in the contexts of the metabolism of UA and of the metal ions in question and from the standpoint of the metabolic properties of metal complexes of UA.
Abbreviations
UA, uric acid; CrUA, 1:1 complex of Cr3+ and uric acid; Cr(UA)3, 1:3 complex of Cr3+ and uric acid; CuUA, 1:1 complex of Cu2+ and uric acid.