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A comparative examination of Patho-Tec reagent-impregnated paper strips and the corresponding classical biochemical tests for the identification of Enterobacteriaceae was made. Patho-Tec papers appeared to be reliable for the cytochrome-oxidase and phenylalanine-deaminase tests. The urease test papers gave false negative reactions inCitrobacter andEnterobacter isolates, but never inProteus strains. The lysine-decarboxylase test papers gave too many false positive results. These shortcomings of the strips interfere with fast and reliable identification ofSalmonella-like Enterobacteriaceae.

1. 1. The metabolism of [8-14C]adenosine was examined in human erythrocytes and erythrocyte lysates. 2. 2. The metabolism of [8-14C]adenosine in erythrocytes is largely dependent upon its concentration. 3. 3. Adenosine deaminase and adenosine kinase activities were assayed in crude erythrocyte lysates. No adenosine phosphorylase activity was detected. 4. 4. Adenosine deaminase exhibited a Km for adenosine of 4 · 10−5 M. Substrate inhibition of the enzyme was exhibited at concentrations of adenosine greater than 2 · 10−4 M. No inhibition of deaminase activity by equimolar or greater concentration of AMP, ADP, ATP, GDP, GTP, Pi, guanylic acid or 2,3-diphosphoglycerate was noted, but 20 % inhibition by high concentrations of adenine and inosine was observed. 5. 5. Adenosine kinase required ATP (Km = 4 · 10−4 M), adenosine (Km = 1.9 · 10−6 M), and Mg2+ for activity. No substrate inhibition by adenosine occurred at concentrations 20 times its Km. Adenosine 5′-triphosphate and Mg2+ were inhibitory at concentrations greater than 1.25 mM and 0.50 mM, respectively. The reaction of ATP with adenosine kinase was competitively inhibited by AMP, ADP, guanylic acid, GDP, IMP, and adenine. Adenosine 5′-triphosphate was variably replaceable as the phosphate donor by a wide range of triphosphates.