The catalase activity of diiron adenine deaminase

Abstract

Adenine deaminase (ADE) from the amidohydrolase superfamily (AHS) of enzymes catalyzes the conversion of adenine to hypoxanthine and ammonia. Enzyme isolated from Escherichia coli was largely inactive toward the deamination of adenine. Molecular weight determinations by mass spectrometry provided evidence that multiple histidine and methionine residues were oxygenated. When iron was sequestered with a metal chelator and the growth medium supplemented with Mn 21 before induction, the post-translational modifications disappeared. Enzyme expressed and purified under these conditions was substantially more active for adenine deamination. Apo-enzyme was prepared and reconstituted with two equivalents of FeSO 4 . Inductively coupled plasma mass spectrometry and Mö ssbauer spectroscopy demonstrated that this protein contained two high-spin ferrous ions per monomer of ADE. In addition to the adenine deaminase activity, [ ]-ADE underwent more than 100 turnovers with H 2 O 2 before the enzyme was inactivated due to oxygenation of histidine residues critical for metal binding. The iron in the inactive enzyme was high-spin ferric with g ave 5 4.3 EPR signal and no evidence of antiferromagnetic spin-coupling. A model is proposed for the disproportionation of H 2 O 2 by [Fe II /Fe II ]-ADE that involves the cycling of the binuclear metal center between the di-ferric and di-ferrous oxidation states. Oxygenation of active site residues occurs via release of hydroxyl radicals. These findings represent the first report of redox reaction catalysis by any member of the AHS.

Transcriptome analysis of Enterococcus faecalis in response to alkaline stress

“…The ade gene (orf00396) encoding adenine deaminase and add gene (orf01977) encoding adenosine deaminase were markedly up-regulated in alkaline stress. Adenine deaminase (ADE) catalyzes the conversion of adenine to hypoxanthine and ammonia (Kamat et al, 2011 ). The transcription of guaD (orf00812) encoding guanine deaminase, guaC (orf00814) encoding guanosine monophosphate (GMP) reductase and guaB (orf02514) encoding inosine 5′-monophosphate dehydrogenase (IMPDH) were markedly enhanced in alkaline stress.…”

Boosting the Catalase‐Like Activity of SAzymes via Facile Tuning of the Distances between Neighboring Atoms in Single‐Iron Sites

“…(Figure S12f). A further comparison with catalase from bovine liver showed impactful images of SAzymes’ robustness, where the white fog burst out from the bottle charged with Fe 2 ‐SAzyme, as soon as the addition of 30 wt % H 2 O 2 [12] . (Video S2) Additionally, recycle experiments showed the well‐retained activity, which were supported by the corresponding TEM and STM images without detectable Fe NPs (Figure S14).…”

“…To further inhibit binding-equilibrium-induced metal dissociation during fabricating, mechanochemistry (ball-milling process) may offer a feasible opportunity, attributed to the remarkable advantages: well dispersion, solvent-free/less and easily scalable process. [10] Inspired by the host-guest strategy developed by Li et al [11] and unique structure-performance relationship of bacterial catalase, [4,12] we devoted our efforts to facile tuning the atomic spacing of neighboring Fe SAzyme (Fe 2 -SAzyme), with mechano-assisted in situ MOF capsulation strategy. Surprisingly, the binary-star-like Fe 2 -SAzyme exhibited a dramatically boosted catalase-like activity, along with the obviously suppressed peroxidase-like activity, by contrast to randomly dispersed Fe 1 -SAzyme (Figure 1b, Video S1-S2).…”

Biochemical Characterization of Kluyveromyces lactis Adenine Deaminase and Guanine Deaminase and Their Potential Application in Lowering Purine Content in Beer

“…The K M value of ADEs has been reported from 40 different clones (wild-type and mutants), which lay in the range of 0.09–2.2 mM (Brenda Database). Klac ADA lies in the mentioned range and is more catalytically efficient in comparison to many ADEs, such as E. coli, Burkholderia sp., P. aeruginosa (Goble et al, 2011 ; Kamat et al, 2011 ).…”