Aspartate aminotransferase activity and isoenzyme proportions in human liver tissues.

Abstract

Aspartate aminotransferase (EC 2.6.1.1) activity and the distribution of its isoenzymes in human liver were examined. Rabbit antiserum against porcin soluble (i.e., non-mitochondrial) enzyme cross-reacted with the soluble enzyme of human origin and was used in an immunoprecipitation assay to quantitate the soluble and mitochondrial isoenzymes. These were separated by rapid, semiquantitative electrophoresis on cellulose acetate and by three other quantitative techniques: isoelectric focusing and anion-and cation-exchange chromatography. The mitochrondrial enzyme averaged 81% of the total activity in normal adult human liver (n = 4). Its contribution was dramatically reduced in single specimens of human fetal liver (56% of total activity) and hepatoblastoma tissue (38%). Total enzyme activities (mumol min-1 per gram of tissue) were: adult, 150; fetal, 38; tumor, 6. Total enzyme concentrations (micromoles of enzyme per kilogram of tissue) found were: adult, 10.8; fetal, 2.7; tumor, 0.4. The concentrations and isoenzyme distribution in human liver are compared to those in various animal model systems. Other methods for quantitative estimation of the isoenzymes and their adaptability for use in estimating concentrations in serum are reviewed.

Prognostic impact of the pretreatment aspartate transaminase/alanine transaminase ratio in patients treated with first‐line systemic tyrosine kinase inhibitor therapy for metastatic renal cell carcinoma

“…5 However, AST is generally synthesized in various types of tissues, whereas ALT synthesis is enriched in liver tissues. 15 Therefore, tissue damage caused by malignant cells or metabolic alterations in highly proliferating cancer cells can lead to an increase of circulating AST levels, but not ALT levels. Furthermore, AST and ALT have been known to catalyze the final products of altered cellular metabolic pathways in malignant cells.…”

A Mechanistic Model of Drug‐Induced Liver Injury Aids the Interpretation of Elevated Liver Transaminase Levels in a Phase I Clinical Trial

“…these observations and Figure 5a,b demonstrate the value of considering the full depth of information obtained 25 and the ALt content reported in Boyd (1983), 22 so this value was chosen as the default value for this application. b Although the model gives users the option of adjusting the half-lives for each ALt/ASt compartment individually, the values were kept equal for this application.…”

Protective effects of Cholestin on ethanol induced oxidative stress in rats

“…It is established that AST can be found in the liver, cardiac muscle, skeletal muscle, kidney, brain, pancreas, lungs, leukocytes and erythrocytes, while Table 1. ALT is present in the liver. 29 Increased levels of serum enzyme such as AST and ALT indicate increased permeability and damage and/or necrosis of hepatocytes. 30 In our study we found that chronic ethanol consumption caused a significant increase in the activities of AST, ALT and ALP, which could cause severe damage to tissue membranes.…”