Alanine isozyme

Evidence accumulating from various laboratories has clearly demonstrated that lithium, at therapeutically relevant concentrations, exerts significant effects on the PKC signaling cascade. Current data suggest that chronic lithium attenuates PKC activity, and down-regulates the expression of PKC isozymes V in the frontal cortex and hippocampus [79, 80], Chronic lithium has also been demonstrated to dramatically reduce the hippocampal levels of a major PKC substrate, myristoylated-alanine-rich C kinase substrate (MARCKS), which has been implicated in regulating long-term neuroplastic events. 

GOTs = sarcoplasmic GOT isozyme GOTm — mitochondrial GOT isozyme GPT = glutamic pyruvic transaminase (alanine aminotransferase) MK = myokinase (adenylate kinase) p.m. = post mortem... 

Although CK and LD isozymes and myoglobin are sensitive biomarkers of skeletal muscle injury, they are also found in cardiac muscle and thus are not tissue specific. Cardiotoxicity must be excluded in order to use them effectively as biomarkers. Injured muscle releases other enzymes in significant amounts, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and aldolase however, these also lack tissue specificity. 

Glutamate-oxaloacetate aminotransferase (GOT) and GPT, possible aliphatic aminotransferases in the amination of 5-keto-octanal instead of L-alanine 5-keto-octanal aminotransferase, were excluded from that function by further work which separated the activities of the former from that of the latter, in mm shown to be composed of two isozymes, although no individual function was described. 

Analysis of the primary sequences of bacterial ALS isozymes and mutant enzymes has revealed the identity of several amino acid residues essential to either enzyme activity or herbicide inhibition. In E. coli ALS, the substitution of alanine 26 by valine in the large subunit diminishes enzymatic activity. " The SMM-resistant ALS I from the same organism has a serine at this position. In yeast, a mutant with SMM tolerance has an ALS with proline 192 replaced by a serine, but the corresponding proline is conserved in an SMM-insensitive E. coli ALS I isozyme, while being altered to a serine in an SMM-sensitive 5. typhimurium ALS II isozyme, " In Saccharomyces cerevisiae, all nuclear and plasmid-borne SMM resistance... 

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