Aspartate transaminase

Older adults are particularly susceptible to a potentially fatal hepatitis when taking isoniazd, especially if they consume alcohol on a regular basis. Two other antitubercular drugs rifampin and pyrazinamide, can cause liver dysfunction in the older adult. Careful observation and monitoring for signs of liver impairment are necessary (eg, increased serum aspartate transaminase, increased serum alanine transferase, increased serum bilirubin, and jaundice). 

ADA American Diabetes Association, adenosine deaminase AST Aspartate transaminase (SGOT) aspartate... 

Chronic copper poisoning in domestic sheep is first characterized by a period of passive accumulation of copper in the tissues. This period varies from a few weeks to more than a year. During this time the animal appears outwardly normal although the liver may contain more than 1000 mg Cu/kg DW and plasma activities of aspartate transaminase, sorbitol dehydrogenase, lactic... 

Elevated aspartate transaminase (AST), alanine transaminase (ALT), and /glutamyl transpeptidase (GGT)... 

Routine liver assessment tests include alkaline phosphatase, bilirubin, aspartate transaminase, alanine transaminase, and y-glutamyl transpeptidase (GGT). Additional markers of hepatic synthetic activity include albumin and prothrombin time. The substances are typically elevated in chronic inflammatory liver diseases such as hepatitis C, but may be normal in others with resolved infectious processes. 

The aminotransferases, aspartate transaminase and alanine transaminase, are enzymes that have increased concentrations in plasma following hepatocellular injury. The highest concentrations are seen in acute viral infections, or ischemic or toxic liver injury. 

FIGURE 21-1. Interpretation of liver function tests. (ALT, alanine transaminase AST, aspartate transaminase CT, computed tomography DDX, differential diagnosis GGT, y-glutamyl transpeptidase.)... 

Mild elevations of serum bilirubin, /globulin, and hepatic transaminase (alanine transaminase and aspartate transaminase) values to about twice normal in acute anicteric disease. 

Patients should have blood urea nitrogen, serum creatinine, aspartate transaminase or alanine transaminase, and a complete blood count determined at baseline and periodically, depending on the presence of other factors that may increase the likelihood of toxicity (advanced age, alcohol abuse, and possibly pregnancy). Hepatotoxicity should be suspected in patients whose transaminases exceed five times the upper limit of normal or whose total bilirubin exceeds 3 mg/dL. At this point, the offending agent(s) should be discontinued, and alternatives selected. 

Figure 1.16 Enzyme aspartate transaminase (= aspartate aminotransferase)...

As examples, two enzymes that will be discussed again later in this chapter are alanine transaminase (alanine aminotransferase) and aspartate transaminase (aspartate aminotransferase). In both cases, the amino group is transferred to 2-oxoglutarate (also known as a-ketoglutarate), which is oxoacid, above, forming glutamate as amino acid2. For example, the alanine transaminase (ALT) reaction is ... 

In effect, glutamate has been synthesized from 2-oxoglutarate, at the expense of alanine. Similarly, the interconversion of aspartate and glutamate catalysed by the enzyme aspartate transaminase (AST) ... 

For example, coupling alanine transamination (via ALT) with GLDH is shown in Figure 6.6b. A similar scheme can be drawn using, for example, aspartate transaminase in place of alanine transaminase. 

Transamination of alanine yields pyruvate catalysed by alanine transaminase (ALT) whilst aspartate produces oxaloacetate catalysed by aspartate transaminase (AST). All transaminase enzymes operate close to a true equilibrium (K eq 1, see Chapter 2) and... 

Catalytic domain 1 doubly wound parallel fi sheet Catalytic domain 2 classic doubly wound fi sheet (Fig. 76) Aspartate transaminase see Aspartate aminotransferase Aspartate transcarbamylase (Monaco et ah, 1978), see Aspartate carbamoyltransferase... 

Determination of the level of cytosolic enzymes such as aspartate transaminase, alanine transaminase, and lactate dehydrogenase is part of standard biochemical liver function tests to measure hepatocellular necrosis [2, 101]. Cytosolic enzymes are not subject to genetic variations inherent in microsomal enzyme production. Liver cytosolic enzymes metabolize several molecules, of which galactose and amino acids are typical examples, used for hepatic function tests. 

This enzyme [EC 2.6.1.1] (also known as transaminase A, glutamicioxaloacetic transaminase, and glutamic aspartic transaminase) catalyzes the reversible reaction of aspartate with a-ketoglutarate to produce oxaloace-tate and glutamate. Pyridoxal phosphate is a required cofactor. The enzyme has a relatively broad specificity, and tyrosine, phenylalanine, and tryptophan can all serve as substrates. 

W13. Wolf, P. L., William, D., Coplon, N., and Coulson, A. S., Low aspartate transaminase activity in serum of patients undergoing chronic hemodialysis. Clin. Chem. 18, 567-568 (1972). 

In a 40-week study in which rats were administered 2-hexanone at 400 mg/kg/day, the levels of liver enzymes (alanine aminotransaminase and aspartate transaminase activities) measured at 4- week intervals were normal (Eben et al. 1979). 

Aspartate transaminase effect. Decoction of the dried rhizome, taken orally by 80 adults of both sexes with hepatitis B antigen-positive chronic hepatitis at a dose of 7.5 g/day for 6 months, was active ° . The treatment consisted of Zingiber officinale (Rh), Bupleurum falcatum (Rt), Scutellaria baicalensis (Rt), Pinellia ternata (Tu), Zizyphus jujuba (Fr), Panax ginseng (Rt), and Glycyrrhiza glabra (Rh) . 

AST aspartate transaminase previously known as SGOT (serum glutamate oxalate transaminase). 

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