JBC, Vol. 250, Issue 15, 6008-6014, Aug, 1975
Purification and characterization of catabolic dehydroquinase, an enzyme in the inducible quinic acid catabolic pathway of Neurospora crassa
J. A. Hautala, J. W. Jacobson, M. E. Case and N. H. Giles
Catabolic dehydroquinase which functions in the inducible quinic acid
catabolic pathway in Neurospora crassa has been purified 8000-fold. The
enzyme was purified by two methods. One used heat denaturation of
contaminating proteins; the other used antibody affinity chromatography.
The preparations obtained by these two methods were identical by all
criteria. The purified enzyme is extremely resistant to thermal
denaturation as well as denaturation 0y urea and guanidine hydrochloride at
25 degrees. It is irreversibly inactivated, although not efficiently
dissociated, by sodium dodecyl sulfate and guanidine hydrochloride at 55
degrees. At pH 3.0, the enzyme is reversibly dissociated into inactive
subunits. At high concentrations catabolic dehydroquinase aggregates into
an inactive, high molecular weight complex. The native enzyme, which has a
very high specific activity, has a molecular weight of approximately
220,000 and is composed of identical subunits of 8,000 to 12,000 molecular
weight each. The native enzyme and the subunit are both asymmetric.