Which statement accurately describes the Tanzer-Gilvarg CK determination method?

Which statement accurately describes the Tanzer-Gilvarg CK determination method?

• A. The forward reaction uses CK, PK, and LDH
• B. The forward reaction uses CK, hexokinase, and G6PD
• C. The reverse reaction uses CK, hexokinase, and G6PD
• D. The reverse reaction uses CK, PK, and LDH

Answer: (A)

The Tanzer-Gilvarg CK determination method measures creatine kinase activity by linking it to two other enzymes so the reaction can be followed spectrophotometrically. In the forward reaction, creatine kinase acts first to convert phosphocreatine and ADP into creatine and ATP. The ATP produced is immediately used by pyruvate kinase together with phosphoenolpyruvate to generate pyruvate and more ATP, effectively transferring the phosphate to push the system toward pyruvate formation. Then lactate dehydrogenase takes that pyruvate and uses NADH to reduce it to lactate, oxidizing NADH to NAD+. The decrease in NADH absorbance at 340 nm is what’s measured, giving a rate that reflects CK activity. This specific coupling—CK with pyruvate kinase and lactate dehydrogenase—defines the forward Tanzer-Gilvarg assay. The alternative coupling with hexokinase and G6PD represents a different assay design, not the Tanzer-Gilvarg method, so the description focusing on CK plus PK and LDH is the correct one for this method.

The Tanzer-Gilvarg CK determination method measures creatine kinase activity by linking it to two other enzymes so the reaction can be followed spectrophotometrically. In the forward reaction, creatine kinase acts first to convert phosphocreatine and ADP into creatine and ATP. The ATP produced is immediately used by pyruvate kinase together with phosphoenolpyruvate to generate pyruvate and more ATP, effectively transferring the phosphate to push the system toward pyruvate formation. Then lactate dehydrogenase takes that pyruvate and uses NADH to reduce it to lactate, oxidizing NADH to NAD+. The decrease in NADH absorbance at 340 nm is what’s measured, giving a rate that reflects CK activity. This specific coupling—CK with pyruvate kinase and lactate dehydrogenase—defines the forward Tanzer-Gilvarg assay.

The alternative coupling with hexokinase and G6PD represents a different assay design, not the Tanzer-Gilvarg method, so the description focusing on CK plus PK and LDH is the correct one for this method.