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Composite Resins↗
Biomedical subjects
J Rogozinski
Publications and source records attributed to J Rogozinski.
Redox potential of the haem c group in the quinocytochrome, lupanine hydroxylase, an enzyme located in the periplasm of a Pseudomonas sp.
The quinocytochrome c, lupanine hydroxylase, was shown to be located in the periplasm of a Pseudomonas sp. The midpoint redox potential of the haem in the purified enzyme was measured by potentiometric titration and shown to be +193 mV. PQQ was removed from the enzyme by isoelectric focusing to give inactive apoenzyme. This resulted in a shift in the midpoint redox potential of the haem to +98 mV. Full activity was recovered by the addition of PQQ to apoenzyme that also restored the original potential.
Cell Fractionation↗
Lupanine hydroxylase, a quinocytochrome c from an alkaloid-degrading Pseudomonas sp.
Lupanine 17-hydroxylase, the first enzyme in the pathway for bacterial degradation of the alkaloid, lupanine, was purified from a Pseudomonas sp. The enzyme acts by initial dehydrogenation of the substrate, and cytochrome c was used as electron acceptor in assays. It had an Mr of 66,000 by ultracentrifuge studies and 74,000 by gel filtration. The visible absorption spectrum was that of a cytochrome c, and a stoicheiometry of one haem group per molecule of enzyme was calculated. SDS/PAGE gave a single band of Mr 72,000 containing the haem group. The enzyme also contained pyrroloquinoline quinone (PQQ), which could be removed by isoelectric focusing. The apoenzyme was reconstituted to full activity with addition of PQQ, and a stoicheiometry of one molecule of PQQ per molecule of enzyme was calculated. Steady-state kinetics gave values of 3.6 microM for the Km for lupanine, 21.3 microM for the Km for cytochrome c and 217 s-1 for the Kcat.
Chromatography, Gel↗