<p>Importance Of Laboratory Detection Of Macro-Aspartate Aminotransferase</p>

Abstract

The macroenzyme form of aspartate aminotransferase (macro-AST) is formed by the binding of AST with immunoglobulins. Macro-AST excretion from serum is prolonged because of its high molecular weight, leading to increased AST activities. Because of the difficulty in detecting macro-AST through routine laboratory tests, affected patients often undergo repeated examinations, with associated anxiety. We report a case in which macro-AST was detected by assaying the patient's serum after refrigeration at 4ºC for 3 days. The sample showed progressive loss of AST activity compared with that frozen in the refrigerator, indicating the presence of macro-AST, which was confirmed as a complex with IgG-κ. The cold storage method was validated using many samples obtained from several patients. Use of this simple method to detect macro-AST may avoid unnecessary examinations and patient anxiety even at primary care facilities.

Macro-aspartate aminotransferase in a healthy woman

“…It allows the nature of enzyme immune complexes to be clarified, but requires high specialisation skills. 9 For the Ig depletion method using protein A and G, instead, proteins A and G are recombinant bacterial proteins used to remove Ig and Ig-AST complexes after incubation with the patient's serum. AST is determined in the supernatant after centrifugation of the sample.…”

“…Electrophoresis for immunofixation with AST staining consists of the electrophoresis of serum proteins using the IgG, IgA and IgM antisera. It allows the nature of enzyme immune complexes to be clarified, but requires high specialisation skills [ 9 ]. For the Ig depletion method using protein A and G, instead, proteins A and G are recombinant bacterial proteins used to remove Ig and Ig-AST complexes after incubation with the patient’s serum.…”

Macro-Aspartate Aminotransferase

“…Аспартатаминотрасфераза (AсАТ) экспрессируется во многих органах и клетках, включая печень, почки, головной мозг, мышечные клетки, эритроциты [1]. АсАТ катализирует переход аминогруппы с α-кетоглютаровой на глютарную кислоту [2].…”

“…Ограниченный доступ к упомянутым диагностическим методам стал поводом для разработки более простого метода диагностики макро-А-сАТ, основанного на результатах исследования D. F. Davidson [1]. После 3 дней хранения активность АсАТ у пациента с макро-АсАТ снизилась с 210 до 43 Е/л (80%).…”

“…Литературные данные о пациентах с доказанной макро-АсАТ с помощью ПЭГ-преципитации или других информативных методов преимущественно представлены описаниями отдельных или небольших серий случаев [1,3,7,9,11,13,[16][17][18][19][20][21][22][23]. Имеется описание случая семейной ма-кро-АсАТ [24].…”