High activity of NADP-dependent malic enzyme in mitochondria from abdomen muscle of the crayfish Orconectes limosus

Mitochondrial NAD(P)-dependent malic enzyme from herring testicular tissue: Purification, kinetic behaviour and regulatory properties

“…The role of the NAD(P)-dependent malic enzyme may be to provide pyruvate to the citric acid cycle. Previously, we showed that malic enzyme converts malate to pyru- vate within the intramitochondrial space and we proposed that this reaction permitted malate oxidation as the sole added substrate by crustacean and fish mitochondria (Skorkowski et al 1977(Skorkowski et al , 1984. These results suggested that malic enzyme was Rates are expressed as pmol coenzyme reduced/min/mg protein.…”

“…Previously, it had been observed that the activity of mitochondrial malic enzyme is extremely high in crayfish abdominal muscle and cod heart (Skorkowski et al 1977(Skorkowski et al , 1984wierczyfiski et al 1980) and in fast regenerating cells and tumors (Nagel et al 1980;Nagel and Sauer 1982;Moreadith and Lehninger 1984). Additionally, the intramitochondrial malate concentration increased after vigorous exercise or treatment of rats with gluconeogenic hormones ).…”

Mitochondrial NAD(P)-malic enzyme from herring skeletal muscle

“…Previously, we observed that the activity of mitochondrial malic enzyme is extremely high in the abdominal muscle of crustaceans and fish heart (Skorkowski et al 1977(Skorkowski et al , 1984. In contrast to mammalian muscle mitochondria, mitochondria isolated from crustacean and fish muscle oxidize malate as the only added substrate, at a high rate (Skorkowski et al 1976(Skorkowski et al , 1984.…”

Purification and properties of the malic enzyme and the malate dehydrogenases from the gill tissue of the ribbed mussel (Modiolus demissus)

“…The values obtained for this ME using the "Chelate" program and Flaschka's formulas indicate that the tenacity of metal binding to this enzyme is much greater than that observed for MEs from various other sources. Previously reported values for metal binding S0.5 values include: E.coli NADP-linked ME Mn2+ S0.5 = 360 nM, Mg2+ S0.5 -54 |iM (Brown and Cook, 1981); potato ME with NADP as cofactor Mn2+ S0.5 = 110 |iM (Grover et al, 1981); crayfish NADP ME Mn2+ S0.5 = 2.5 |xM (Skorkowski et al, 1977); protozoan (Crithidia fasciculata) NADP-linked ME Mn2+ S0.5 = 10 |iM (Marr, 1973).…”

“…The intracellular distribution of ME, a feature which is linked to its function, has been determined for a few invertebrate species. The ME activity in crustacean, helminth and annelid tissue is mitochondrial (Skorkowski et al, 1977;Li et al, 1972;Landsperger et al, 1978;Hoffmann et al, 1979). ME activity is localized to the cytosol of the oyster adductor muscle , the sea mussel hepatopancreas, and the sea mussel mantle, but is about equally distributed between the cytosolic and mitochondrial compartments of the sea mussel adductor muscle (deZwaan and van Marrewijk, 1973).…”