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Publication Abstract from PubMed

The bacterial cytochrome P450cam catalyzes the oxidation of camphor to 5-exo-hydroxycamphor as the first step in the oxidative assimilation of camphor as a carbon/energy source. CYP101D1 is another bacterial P450 that catalyzes the same reaction. A third P450 (P450tcu) has recently been discovered that has approximately 86% sequence identity to P450cam as well as very similar enzymatic properties. P450tcu, however, exhibits three unusual features not found in P450cam. First, we observe product in at least two orientations in the x-ray structure which indicates that, unlike P450cam, x-ray generated reducing equivalents can drive substrate hydroxylation in crystallo. We postulate, based on molecular dynamic simulations, that greater flexibility in P450tcu enables easier access of protons to the active site and, together with x-ray driven reduction, results in O2 activation and substrate hydroxylation. Second, the characteristic low- to -high-spin transition when camphor binds occurs immediately with P450cam but is very slow in P450tcu. Third, isothermal titration calorimetry shows that in P450cam substrate binding is entropically driven with DeltaH>0 while in P450tcu DeltaH<0 with a more modest change in -TDeltaS. These results indicate that despite nearly identical structures and enzymatic properties, these two P450s exhibit quite different properties most likely related to differences in conformational dynamics.

Unexpected Differences Between Two Closely Related Bacterial P450 Camphor Monooxygenases.,Murarka VC, Batabyal D, Amaya JA, Sevrioukova I, Poulos TL Biochemistry. 2020 Jun 17. doi: 10.1021/acs.biochem.0c00366. PMID:32551522^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.