Treatment of isolated rat hepatocytes with saturating concentrations of glucagon caused several modifications properties of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40): S0.5 (substrate concentration at half maximum velocity) for phosphoenolpyruvate was about doubled, whereas Vmax was not changed; the activity measured at 0.15 mM phosphoenolpyruvate (physiological concentr...

Discussion From the standpoint of attempting to elucidate the mechanisms whereby pyruvate kinase activity might be regulated in vivo, the results obtained to date, and summarized above, are largely inconclusive. Whereas the enzyme in vitro has been shown to be inhibited by ATP, limiting Mg2+, creatine phosphate, etc., the inhibition is probably insufficient in magnitude to account per se for th...

The relationships among and the properties of the pyruvate kinase isozymes are reviewed, emphasizing their potential role in carcinogenesis. Particular consideration is given to evaluation of the concept that the three major nonreadily interconvertible forms are the products of distinct genes, the relationship of these forms to additional separable forms of pyruvate kinase, the types and possib...

The embryonic stem cells (ESCs) are pluripotent, self-renewing that able to differentiate into any of the germ layers involved in embryogenesis. However, molecular mechanisms control ESC pluripotency and differentiation remain poorly understood. family Pyruvate dehydrogenase kinase (PDK1-4), inactivates mitochondrial pyruvate complex via phosphorylation, plays a crucial role glucose homeostasis...

We have presented evidence that stimulation of pyruvate dehydrogenase, (PDH.) kinase activity by pyruvate or by acetyl-CoA is mediated through acetylation of lipoyl moieties (Cate, R. L., and Roche, T. E. (1978) J. Biol. Chem. 253,496-503). In accord with this indirect mechanism for the action of these effecters, we now find that the degree of stimulation of PDH, kinase increases with the level...

The control of pyruvate dehydrogenase activity by inactivation and activation was studied in intact mitochondria isolated from rabbit heart. Pyruvate dehydrogenase could be completely inactivated by incubating mitochondria with ATP, oligomycin, and NaF. This loss in dehydrogenase activity was correlated with the incorporation of 32P from [gamma-32P]ATP into mitochondrial protein(s) and with a d...

The interaction of platinum complexes with bovine heart pyruvate kinase (PK) was studied by absorption, CD, fluorescence spectroscopy and enzymic activity test. Our results showed that activity of PK was reduced by cis-DDP and potassium tetrachloroplatinate in a time-and concentration dependent manner. Cis-DDP was less effective than K2PtCl4 in reducing PK activity. The native enzyme showed wel...

F igure 1. Effect of pyruvate kinase (c) on rate of pyruvate formation from PEP and phosphatase. The rate of NADH oxidation was followed by measuring 4̂340nm in a solution containing, in DaO at 15 °C: sodium maleate (40 nM, pD 6.0), EDTA (0.1 ium), MgCl2 (1 him), KC1 (50 him), NADH (0.12 him) , NAD+ (50 jim), acid phosphatase (Sigma IV, 150 jig), L-LDH (25 pg), and PEP (1 him) added last. Pyruva...

Lardy and Ziegler (1) obtained synthesis of phosphoenol pyruvate from pyruvate and adenosine triphosphate by reversal of the pyruvate kinase reaction. A possible mechanism was thus demonstrated for the initial step in the synthesis of glycogen from pyruvate. The amounts of phosphoenol pyruvate synthesized were, however, small, and it is rather widely held that reversal of the pyruvate kinase re...

We have presented evidence that stimulation of pyruvate dehydrogenase, (PDH.) kinase activity by pyruvate or by acetyl-CoA is mediated through acetylation of lipoyl moieties (Cate, R. L., and Roche, T. E. (1978) J. Biol. Chem. 253,496-503). In accord with this indirect mechanism for the action of these effecters, we now find that the degree of stimulation of PDH, kinase increases with the level...