catalytic mechanism: a first water molecule is a hydroxide ion that is bound as a bridge between the two metal ions and attacks the carbonyl carbon of the substrate. A second water molecule is bound to the carboxyl group of Glu122 and functions as a proton donor in catalysis
removal of the zinc ions by dialyzing against buffers containing o-phenanthroline results in a partial decrease of 10-30% in activity and zinc content. Wild-type enzyme, purified in the presence of EDTA, shows only half the activity of the wild-type enzyme, the activity is recovered by the addition of ZnCl2 or MnCl2
; crystal structures of the native and the Mn2+-activated enzyme determined by a difference Fourier method, crystal structure of Mn2+-activated enzyme determined by the single isomorphous replacement method
crystal structure of the enzyme complexed with a 1-methylguanidine. All subunits in the complex exist as the closed form. X-ray crystallographic study and the atomic absorption spectrometry analysis of the E122Q mutant-substrate complex reveal that the drastic decrease of the activity of the E122Q is caused by the loss of one Zn ion at the Metal1 site and a critical function of Glu122
construction of an electrochemical biosensor for creatinine based on the immobilization of creatininase, creatinase and sarcosine oxidase onto a ferrocene/horseradish peroxidase/gold nanoparticles/multi-walled carbon nanotubes/Teflon composite electrode,method development and evaluation, overview
construction of a biosensor by co-immobilization of creatininase, creatinase, and sarcosine oxidase onto iron oxide nanoparticles/chitosangraft-polyaniline, Fe3O4-NPs/CHIT-g-PANI, composite film electrodeposited on surface of Pt electrode through glutaraldehyde coupling. The creatinine biosensor uses enzymes/Fe3O4-NPs/CHIT-g-PANI/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode. The biosensor exhibits an optimum response within 2 s at pH 7.5 and 30°C, when polarized at 0.4 V versus Ag/AgCl. The electrocatalytic response shows a linear dependence on creatinine concentration ranging from 1 to 800 microM. The sensitivity of the biosensor is 3.9 microA per microM and cm2, with a detection limit of 1 microM. The biosensor shows only 10% loss in its initial response after 120 uses over 200 days, when stored at 4°C. The biosensor measures creatinine in the serum of apparently healthy persons
Serafin, V.; Hernandez, P.; Agui, L.; Yanez-Sedeno, P.; Pingarron, J.
Electrochemical biosensor for creatinine based on the immobilization of creatininase, creatinase and sarcosine oxidase onto a ferrocene/horseradish peroxidase/gold nanoparticles/multi-walled carbon nanotubes/Teflon composite electrode