Creatinine deaminase

One of the pitfalls of microbial sensors, viz. their low selectivity, can be overcome by combining cells with an immobilized enzyme. Thus, creatinine deaminase (CDA, EC 3.5.4.21) hydrolyses creatinine to N-methylhydantoin and ammonium ion, the ammonia produced being successively oxidized to nitrite and nitrate ion by nitrifying bacteria. These bacteria have not yet been characterized but are known to be a mixed culture of Nitrosomonas sp. and Nitrobacter sp. The reaction sequence involved is as follows ... 

The bacteria consume oxygen during ammonia oxidation, so oxygen depletion can be detected by using an oxygen electrode. A combined creatinine sensor thus consists of a cellulose dialysis membrane, immobilized creatinine deaminase, immobilized nitrifying bacteria and an oxygen electrode [130]. 

Creatinine deaminase (EC 3.5.4.21 creatinine imino-hydrolase) catalyzes the conversion of creatinine to N-methylhydantoin and ammonia. Early methods concentrated on tlie detection of ammonia using either glutamate dehydrogenase or the Berthelot reaction. An alternative approach involves the enzyme N-methylhydantoin amido-hydrolase (Figure 24-l,D). ... 

Tabata M, Kidneyo T, Totani M. Automated assay of creatinine in serum as simplified by the use of immobilised enzymes, creatinine deaminase and glutamate dehydrogenase. Anal Biochem 1983 134 44-9. 

Creatinine Creatine deaminase N-Methylhydantoin, NH4 Tris/NaH2P04 pH 8.5 NH3-Gas-Sensor 1-100 mg %... 

Table 7.1.4 Concentration range of purine and pyrimidine metabolites in urine (pmol/mmol creatinine) from patients. ADA Adenosine deaminase, APRT adenine phosphoribosyltransferase, ASA adenylosuccinate lyase, DHP dihydropyrimidinase, DPD dihydropyrimidine dehydrogenase, HGPRT hypoxanthine-guanine phosphoribosyltransferase, PNP purine nucleoside phosphorylase, TP thymidine phosphorylase, UMPS uridine monophosphate synthase, / -UP fi-ureidopropionase... 

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