Glycolytic enzymes in polyamine-treated bovine retina.
The retina is characterized by glycolysis under aerobic conditions, mediated by lactate dehydrogenase isoenzyme-5 (LDH-5) as well as by the soluble isoenzyme of malate dehydrogenase. Bovine retina LDH and MDH isoenzymes and their activities were studied after polyamine treatment. Our results showed that LDH-5 isoenzyme presented the highest activity in untreated as well as in putrescine-treated retina. Decreased activity was present when the retina was treated with spermidine or spermine. It was demonstrated that retinic LDH-5 had a high affinity for lactate which enabled the isoenzyme to be more effective than the other LDH isoenzymes in the conversion of NADH to NAD. Therefore, the putrescine enhancing LDH-5 activity appeared to be capable of stimulating NAD-mediated rhodopsin regeneration. Putrescine induced a marked increase of both MDH isoenzymes--soluble (s-MDH) and mitochondrial (m-MDH), while spermine and spermidine mostly affected the soluble form of the enzyme. Putrescine induced a three-fold increase in s-MDH and m-MDH activities, while spermine and spermidine induced a four to five-fold increase in s-MDH. These results document the differential effects of polyamine treatment on LDH and MDH isoenzyme activities.
Venza
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I
Institute of General Pathology, Faculty of Medicine and Surgery, University of Messina, Italy.
Valenti
A
A
Ruggeri
P
P
Denaro
L
L
Teti
D
D
D000818:Animals; D002417:Cattle; D006019:Glycolysis; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D000080864:Lactate Dehydrogenase 5; D008315:Malondialdehyde / Q000378:metabolism*; D011073:Polyamines / Q000494:pharmacology*; D011700:Putrescine / Q000494:pharmacology; D012160:Retina / Q000187:drug effects / Q000201:enzymology*; D013095:Spermidine / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology
D007527:Isoenzymes; D011073:Polyamines; D013096:Spermine; D008315:Malondialdehyde; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; D013095:Spermidine; D011700:Putrescine