Interpain A

Potempa, Jan

doi:10.1016/b978-0-12-382219-2.00485-3

Cited by 1 publication

(1 citation statement)

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“…Residual enzyme activity was determined by measurement of fluorescence (λ ex = 380 nm and λ em = 460 nm) of AMC (7-amino-4-methylcoumarin) released from t-butoxycarbonyl-Val-Leu-Lys-AMC as described previously [ 13 ]. Immediately before use, InpA was activated by incubation for 15 min with 3 mM DTT in 0.1 M Tris–HCl, 0.14 M NaCl, pH 7.5 [ 50 ]. When used for protein breakdown assays under non-reducing conditions, the above buffer was exchanged for that without reducing agent by ultrafiltration using 10 kDa cut-off Microcons (Amicon).…”

Section: Methodsmentioning

confidence: 99%

Breakdown of albumin and haemalbumin by the cysteine protease interpain A, an albuminase of Prevotella intermedia

et al. 2015

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BackgroundPrevotella intermedia is a Gram-negative black-pigmenting oral anaerobe associated with periodontitis in humans, and has a haem requirement for growth, survival and virulence. It produces an iron porphyrin-containing pigment comprising monomeric iron (III) protoporphyrin IX (Fe(III)PPIX.OH; haematin). The bacterium expresses a 90-kDa cysteine protease termed interpain A (InpA) which both oxidizes and subsequently degrades haemoglobin, releasing haem. However, it is not known whether the enzyme may play a role in degrading other haem-carrying plasma proteins present in the gingival sulcus or periodontal pocket from which to derive haem. This study evaluated the ability of InpA to degrade apo- and haem-complexed albumin.ResultsAlbumin breakdown was examined over a range of pH and in the presence of reducing agent; conditions which prevail in sub- and supra-gingival plaque. InpA digested haemalbumin more efficiently than apoalbumin, especially under reducing conditions at pH 7.5. Under these conditions InpA was able to substantially degrade the albumin component of whole human plasma.ConclusionsThe data point to InpA as an efficient “albuminase” with the ability to degrade the minor fraction of haem-bound albumin in plasma. InpA may thus contribute significantly to haem acquisition by P. intermedia under conditions of low redox potential and higher pH in the inflamed gingival crevice and diseased periodontal pocket where haem availability is tightly controlled by the host.

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Section: Methodsmentioning

confidence: 99%