Authentic Biochemistry

CPS-1 activity is regulated by liver enriched transcription factors as well as Sirtuin-mediated de-acylation. Glutaminase breaks down glutamine into glutamate and ammonia. Glutamate also yields additional NH4+ via the enzyme glutamate dehydrogenase. From here, ammonia is initially incorporated into hepatocyte mitochondria and ultimately results in the formation of urea. Urea subsequently leaves the hepatocyte cytoplasm and is ultimately excreted in urine. Glutaminase-1 (GLS1) is a mitochondrial enzyme found in endothelial cells (ECs) that metabolizes glutamine to glutamate and ammonia and glutaminolysis modulates the function of human umbilical vein endothelia.Glutamine deprivation or GLS1 inhibition also stimulated the production of reactive oxygen species and this was associated with a marked decline in heme oxygenase-1 (HO-1) expression. GLS1 inhibition also sensitized umbilical endothelia to the cytotoxic effect of hydrogen peroxide; a process that is blocked by the overexpression of Heme oxygenase 1. In