PubMed · 6732395
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G D Strasberg. 1984. Hypothyroidism and isozyme elevations.. https://doi.org/10.1001/archinte.144.6.1313
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We have recently discovered an alternative function of the putative metastasis suppressor protein Nm23, which is identical to nucleoside diphosphate kinase, as a protein phosphotransferase in vitro. While purified native Nm23 protein did not phosphorylate other proteins, we could purify a Nm23-associated protein that activates the protein phosphotransferase function; it was identified as a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) isoenzyme. Co-expression and purification of (His)6-tagged GAPDH in combination with either Nm23-H1 or Nm23-H2 in baculovirus-infected Sf9 cells showed that only Nm23-H1, but not Nm23-H2, forms a stable complex with GAPDH. Protein phosphotransferase activity was confirmed for the recombinant GAPDH.Nm23-H1 complex but not for either of the enzymes alone, nor was this activity observed after simple mixing of the purified proteins in vitro. The molecular mass of the highly purified recombinant GAPDH.Nm23-H1 complex suggests that a dimer of GAPDH interacts with a dimer of Nm23-H1. In contrast to the complex with GAPDH, co-expression of Nm23-H1 with antioxidant protein (MER-5) or creatine kinase did not activate the protein phosphotransferase function, indicating that this activation may specifically require GAPDH as a binding partner.
Recent advances in analytic techniques have increased the diagnostic value of creatine kinase MB (CK-MB), enabling earlier and more sensitive results. The CK-MB mass immunoassays, that utilise the monoclonal anti-CK-MB in conjunction with anti-M or anti-B antibodies, are able to measure accurately small changes during the early hours after myocardial infarction (MI). CK-MB has two main limitations in diagnosing MI neither of which however undermines its established clinical value: CK-MB is not perfectly specific to cardiac injury, with increase occurring also during massive musculoskeletal injury; furthermore, the early release pattern of CK-MB limits its value for the late MI diagnosis. For the foreseeable future evidence is compelling for greater access to rapid testing capabilities in emergency situations, using protocols incorporating CK-MB mass evaluation together with other biochemical markers, i.e. myoglobin and troponins.
PURPOSE: The creatine kinase level indicates sperm maturity and correlates with the spermatozoal fertilizing potential. The relationship between creatine kinase levels in subfertile men and their clinical diagnosis was examined. METHODS: Patients with unexplained infertility (n = 34), varicocele (n = 20), postvasectomy reversal (n = 7), or cancer (n = 22) were included in this prospective clinical study. The control group consisted of healthy normal donors (n = 15). RESULTS: The median and interquartile range values of creatine kinase for each group were as follows: normal donors, 0.061 U/10(8) sperm (0.056 to 0.076 U/10(8) sperm); idiopathic male factor, 0.119 U/10(8) sperm (0.061 to 0.190 U/10(8) sperm); varicocele, 0.392 U/10(8) sperm (0.209 to 1.494 U/10(8) sperm); postvasectomy reversal, 0.589 U/10(8) sperm (0.425 to 4.043 U/10(8) sperm); and cancer, 0.068 U/10(8) sperm (0.047 to 0.168 U/10(8) sperm). Sperm creatine kinase levels were significantly higher in patients with varicocele compared to normal donors (P = 0.0001), cancer patients (P = 0.0002), and men with idiopathic infertility (P = 0.0009). Sperm concentration and creatine kinase level were inversely correlated in patients (r = -0.7, P < 0.001) but not in normal donors. CONCLUSIONS: Semen quality is poorer in subfertile patients with clinical varicocele and postvasectomy reversal than in cancer patients and patients with idiopathic male infertility. That the creatine kinase levels in cancer patients were similar to those of normal donors suggests that the final phase of spermatogenesis may not be altered in men with cancer; thus semen from these patients should be banked to ensure fertility after cancer treatment.