Cellular studies of the two main isoforms of human <scp>d</scp> ‐aspartate oxidase

Human d-aspartate oxidase (hDASPO) is a FAD-dependent enzyme responsible for the degradation of (d-Asp). In mammalian central nervous system, d-Asp behaves as classical neurotransmitter, it thought to be involved in neural development, brain morphology and behavior, appears several pathological states, such schizophrenia Alzheimer's disease. Apparently, human DDO gene produces alternative transcripts encoding three putative hDASPO isoforms, constituted by 341 (the ‘canonical’ form), 369, 282 amino acids. Despite increasing interest its physiological role, little known about these different isoforms. Here, additional N-terminal peptide present hDASPO_369 isoform only has been identified hippocampus Alzheimer’s disease female patients, while peptides corresponding remaining part protein were samples from male healthy controls patients. The was largely expressed E. coli insoluble protein, hampering with biochemical characterization. Furthermore, we generated U87 glioblastoma cell clones stably expressing hDASPO_341 and, first time, isoforms; latter showed lower expression compared canonical isoform. Both isoforms are active (showing similar kinetic properties), localize peroxisomes, very stable (a half-life approximately 100 h estimated), primarily degraded through ubiquitin–proteasome system. These studies shed light on properties final aim clarify mechanisms controlling levels neuromodulator d-Asp.