The effect of phosphate buffer in the range of pH 5.80–8.07 on jack bean urease activity

Urease: Recent Insights on the Role of Nickel

“…These results suggest that phosphate inhibition of urease requires the protonation of an ionizable group with pK a1 ϭ 6.3 [52]. Similar results were more recently obtained for JBU [62], where the pH-dependence of phosphate inhibition was investigated in the range 5.8-8.1. It was shown that phosphate is a competitive inhibitor in the pH range 5.8-7.5, with K i values increasing from 0.53 mM at pH 5.8 to 123 mM at pH 7.5.…”

Effect of enzyme location on activity and stability of trypsin and urease immobilized on porous membranes by using layer-by-layer self-assembly of polyelectrolyte

“…6(b)). The inhibitory action of phosphate buffer below pH 7.0-7.5 has been reported in literature and ascribed to H 2 PO 4 − ion [37]. The pH dependent inhibitory strength decreases with an increase in pH and stops at pH 7.0-7.5.…”

Potentiometric Study of Urease Kinetics over pH 5.36–8.21

“…5b) is unlike the aformentioned ones in that it has two maxima located at a short distance of 0.7 pH unit. Surprisingly, an indepth analysis of some v max -pH profiles reported in the literature as bell-shaped [43,44,47] reveals that the profiles do have this characteristic shape, which was seemingly overlooked by the authors. Our preliminary analysis of this shape has shown that it cannot be interpreted in terms of the monoprotonation-deprotonation scheme of the enzyme active site groups hitherto used for ureases [41 ± 45], for which the distance between the maxima must be at least 2 pH units, but requires a more complex protonationdeprotonation scheme.…”