Inhibition of creatine kinase activity by lysine in rat cerebral cortex.
Accumulation of lysine (Lys) in tissues and biochemical fluids is the biochemical hallmark of patients affected by familial hyperlysinemia (FH) and also by other inherited neurometabolic disorders. In the present study, we investigated the in vitro effect of Lys on various parameters of energy metabolism in cerebral cortex of 30-day-old Wistar rats. We verified that total (tCK) and cytosolic creatine kinase activities were significantly inhibited by Lys, in contrast to the mitochondrial isoform which was not affected by this amino acid. Furthermore, the inhibitory effect of Lys on tCK activity was totally prevented by reduced glutathione, suggesting a possible role of reactive species oxidizing critical thiol groups of the enzyme. In contrast, Lys did not affect (14)CO(2) production from [U-(14)C] glucose (aerobic glycolytic pathway) and [1-(14)C] acetic acid (citric acid cycle activity) neither the various activities of the electron transfer chain and synaptic Na(+)K(+)-ATPase at concentrations as high as 5.0 mM. Considering the importance of creatine kinase (CK) activity for brain energy metabolism homeostasis and especially ATP transfer and buffering, our results suggest that inhibition of this enzyme by Lys may contribute to the neurological signs presented by symptomatic patients affected by FH and other neurodegenerative disorders in which Lys accumulates.
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, UFRGS, Rua Ramiro Barcelos, RS, Brasil.
Anelise Miotti
AM
Tonin
Gustavo Costa
GC
Ferreira
Patrícia Fernanda
PF
Schuck
Carolina Maso
CM
Viegas
Angela
A
Zanatta
Guilhian
G
Leipnitz
Bianca
B
Seminotti
Clóvis Milton
CM
Duvall Wannmacher
Moacir
M
Wajner
D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D003402:Creatine Kinase / Q000378:metabolism*; D004195:Disease Models, Animal; D004579:Electron Transport / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005978:Glutathione / Q000502:physiology; D020167:Hyperlysinemias / Q000201:enzymology*; D007527:Isoenzymes; D008239:Lysine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D007527:Isoenzymes; D003402:Creatine Kinase; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione; D008239:Lysine