An electrophysiological study of N-acetyl-L-aspartic acid (NAAA) on the stellate ganglion of the squid

N-Acetylaspartate Is an Important Brain Osmolyte

Most of the human diseases related to various proteopathies are confined to the brain, which leads to the development of various forms of neurological disorders. The human brain consists of several osmolytic compounds, such as N-Acetylaspartate (NAA), myo-inositol (mI), glutamate (Glu), glutamine (Gln), creatine (Cr), and choline-containing compounds (Cho). Among these osmolytes, the level of NAA drastically decreases under neurological conditions, and, hence, NAA is considered to be one of the most widely accepted neuronal biomarkers in several human brain disorders. To date, no data are available regarding the effect of NAA on protein stability, and, therefore, the possible effect of NAA under proteopathic conditions has not been fully uncovered. To gain an insight into the effect of NAA on protein stability, thermal denaturation and structural measurements were carried out using two model proteins at different pH values. The results indicate that NAA increases the protein stability with an enhancement of structure formation. We also observed that the stabilizing ability of NAA decreases in a pH-dependent manner. Our study indicates that NAA is an efficient protein stabilizer at a physiological pH.

Inhibition by N-acetyl-aspartate of aspartate binding to a proteolipid fraction from rat cerebral cortex

Many roles have been suggested for N-acetyl-aspartate in brain function because of it being located almost exclusively in that organ. However, its true role remains to be demonstrated. We show here that N-acetyl-aspartate: 1) binds to a hydrophobic protein fraction from the cerebral cortex of the rat, which specifically binds L-aspartate, L-glutamate, and gamma-amino-butyric acid; and 2) has a marked inhibitory effect on the aspartate binding sites of this proteolipid fraction. Structural analogs of N-acetyl-aspartate, i.e. N-carbamyl-aspartate and N-methyl-aspartate also inhibit the L-aspartate binding by the brain protein fraction used.