Rapid assay of human serum total phosphoglyceric acid mutase activity and application to clinical evaluation of acute myocardial infarction

Phosphoglyceric acid mutase (PGAM; BC 5. 4. 2. 1) is one of the enzymes in the glycolytic pathway, and catalyzes the interconversion of 2- and 3-phosphoglycerate when 2, 3-bisphosphoglycerate is present as a cofactor. PGAM consists of two subunits of types M and B in the same manner as creatine phosphokinase (BC 2. 7. 3. 2). We report here basic studies examining PGAM activity assay in human serum and its clinical significance as a diagnostic factor for (AMI). All of our experiments were performed using home-made reagents for the PGAM assay and a COBAS MIRA analyzer (Roche Co. ) for measurements. Each sample (5μ1) was added to 360μ 1 of PGAM activity assay reagent cf. , (Methods of Enzymatic Analysis, 2: 282) and reacted at 37°C for 5 minutes. Within-run precision studies yielded CVs of 2.0% and 3.3% on mean sample activities of 77 U/1 and 224 U/1, respectively. The linearity of the PGAM response was extended to 1700 U/l. The stability of reconstituted serum and EDTA plasma appeared to last for 6 days at 4°C and -25°C, respectively. The reference values of PGAM ranged from 14 U/l to 65 U/l. The correlation between findings with PGAM and other cardiac markers using plasma from AMI patients (n=21) was relative (T-CK: r=0.89; GOT: r=0.86), whereas it was absolute (T-CK: r=-O.08, CK-MB: r=0.30) when plasma from aortocoronary bypass surgery patients (n=50) was used, an effect due to the change in PGAM levels in erythrocytes due to hemolysis associated with surgery. After the onset of AMI, PGAM levels showed a sharp peak earlier than other parameters such as T-CK.