Like glutamate, aspartate is synthesized by a simple one-step transamination reaction catalyzed by aspartate aminotransferase, AST (formerly referred to as serum glutamate-oxalate transaminase, SGOT). Humans express two different AST enzymes, both of which function as homodimeric enzymes. One AST enzyme is a cytosolic enzyme and the other is a mitochondrial enzyme. The cytosolic AST enzyme is synthesized by the GOT1 gene (glutamate-oxalate transaminase 1) that is located on chromosome – and is composed of 9 exons that encode a 413 amino acid protein. The mitochondrial AST enzyme is synthesized from the GOT2 gene that is located on chromosome 16q21 and is composed of 10 exons that generate two alternatively spliced mRNAs that encode two different isoforms: isoform 1 (430 amino acids) and isoform 2 (387 amino acids).
The protein fractions obtained from the purification of 2-methylisocitrate dehydratase were analysed by SDS/PAGE. The apparent molecular mass of the 2-methylisocitrate dehydratase subunit was determined by measuring the mobility by SDS/PAGE (15% acrylamide) [ 19 ] with standard proteins as molecular mass markers. Purified 2-methylisocitrate dehydratase was blotted from the gel (10% acrylamide) on a poly(vinylidene difluoride) membrane (Millipore) with the transblot SD semidry transfer cell (Bio-Rad), as described in the manufacturer's protocol, and was then N-terminally sequenced by Edman degradation (kindly performed by D. Linder, Universität Gießen, Germany).
In 1904, the German chemist Franz Knoop elucidated the steps in beta-oxidation by feeding dogs odd- and even-chain ω-phenyl fatty acids, such as ω-phenylvaleric acid and ω-phenylbutyric acid, respectively. The mechanism of beta-oxidation, . successive removal of two carbons, was realized when it was discovered that the odd-chain ω-phenylvaleric acid was metabolized to hippuric acid , and that the even-chain ω-phenylbutyric acid was metabolized to phenaceturic acid . At this time, any reaction mechanism involving oxidation at the beta carbon was as yet unknown in organic chemistry .