Aminotransferaza asparaginianowa – kluczowy enzym w metabolizmie ogólnoustrojowym człowieka

Abstract

Aspartate aminotransferase is an organ-nonspecific enzyme located in many tissues of the human body where it catalyzes reversible reaction of transamination. There are two aspartate aminotransferase isoforms--cytoplasmic (AST1) and mitochondrial (AST2), that usually occur together and interact with each other metabolically. Both isoforms are homodimers containing highly conservative regions responsible for catalytic properties of enzyme. The common feature of all aspartate aminotransfeses is Lys - 259 residue covalent binding with prosthetic group - pyridoxal phosphate. The differences in the primary structure of AST isoforms determine their physico-chemical, kinetic and immunological properties. Because of the low concentration of L-aspartate (L-Asp) in the blood, AST is the only enzyme, which supply of this amino acid as a substrate for many metabolic processes, such as urea cycle or purine and pyrimidine nucleotides in the liver, synthesis of L-arginine in the kidney and purine nucleotide cycle in the brain and the skeletal muscle. AST is also involved in D-aspartate production that regulates the metabolic activity at the auto-, para- and endocrine level. Aspartate aminotransferase is a part of the malate-aspartate shuttle in the myocardium, is involved in gluconeogenesis in the liver and kidney, glyceroneogenesis in the adipose tissue, and synthesis of neurotransmitters and neuro-glial pathway in the brain. Recently, the significant role of AST in glutaminolysis - normal metabolic pathway in tumor cells, was demonstrated. The article is devoted the role of AST, known primarily as a diagnostic liver enzyme, in metabolism of various human tissues and organs.

Dietary Copper Deficiency Leads to Changes in Gene Expression Indicating an Increased Demand for NADH in the Prefrontal Cortex of the Rat’s Brain

“…Studies have also demonstrated evidence that gluconeogenesis exists in brain astrocytes, but no convincing data have yet been found in neurons [ 36 ]. Therefore, activation of the pathway at the GOT2 level may be associated with an increase in the demand for gluconeogenesis intermediators but used for purposes other than glucose synthesis, for example, for the synthesis of glycerol (glyceroneogenesis in adipose tissue) [ 37 , 38 ] and in the case of the brain, synthesis of neurotransmitters, and neuroglial pathway [ 39 ].…”

1,25(OH)2D3 attenuates hepatic insulin resistance in rats with streptozotocin-induced diabetes via antioxidation

“…ALT and AST are biochemical markers of liver injury [21]. Previous studies have found that 1,25(OH)2D3 protects the rat liver from injury [22].…”

A Cell-Based Metabonomics Approach to Investigate the Varied Influences of Chrysophanol-8-O-β-D-Glucoside With Different Concentrations on L-02 Cells

“…AST is also one of the most commonly used indicators for diagnosis of liver disease. When the hepatocyte is damaged, the permeability of the cell membrane increases, and the AST outflows from the cell (Otto-Ślusarczyk et al, 2016). The decrease in L-aspartic might be caused by the outflow of AST.…”