| 摘要 |
An enzymatic process for the determination of beta -lactam antibiotics in a biological liquid, comprising the steps of (1) incubating the liquid with soluble D-alanyl-D-alanine-carboxypeptidase produce by Actinomadura R39, the beta -lactam antibiotic reacting with the enzyme to form an inactive and equimolecular enzyme-antibiotic complex; (2) incubating the mixture obtained with a solution of a thioester substrate having the formula <IMAGE> wherein R1=benzoyl, phenylacetyl or N alpha -acetyl-L-lysyl, R2=glycyl or D-alanyl, and R3=hydrogen or methyl so as to form, by hydrolysis, a 2-mercaptoalkanoic acid having the formula <IMAGE> in an amount proportional to the residual enzymatic activity, said incubation being further conducted in the presence of glycine or of a D-amino acid; (3) determining the amount of 2-mercaptoalkanoic acid formed, and (4) comparing the determination of step (3) with a standard, to obtain the antibiotic concentration in the biological liquid. A test set for carrying out this process is also disclosed.
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