Mechanism-based inactivation of glutamate decarboxylase and aspartate aminotransferase with L-serine-O-sulfate

The mechanism-based inactivation of glutamate decarboxylase (GAD) of E. coli Sukhareva, B. S. & Braunstein, A. E. (1971) Mol. Biol. 5, 302 and of cytosolic aspartate aminotransferase (AAT) by L-serine-O-sulfate John, R. A. & Fasella, P. (1969) Biochem. 8, 4477 has been reinvestigated. The 336 nm form of GAD (1) releases a low molecular weight yellow compound 2 at high pH Likos, J. J. & Metzler, D. E. (1976) Fed. Proc. 35, 1545. The identical compound is released from AAT. Compound 2 is a known compound synthesized by an aldol condensation between pyridoxal phosphate (PLP) and pyruvate Schnackerz, K. D. et al. (1979) Biochem. 18, 3557. The identity of 2 was recognized by Likos private communication. The characterization of 2 isolated from GAD and AAT and comparison with synthetic 2 by 300 MHz NMR spectroscopy is described. The structure of 1 is proposed in collaboration with Likos as an adduct formed by attack of the (beta)-carbon of (alpha)-aminoacrylate on the internal Schiff base of PLP with a lysine side chain from the protein. Aminoacrylate is generated from serine sulfate by enzyme-catalyzed (beta)-elimination. Compound 2 is presumably released by attack of hydroxyl ion on 1. Release is prevented by treatment with NaBH(,4) which reduces the C=N or C=O linkage in 1 thereby lowers the acidity of the (beta)-proton removed in the formation of 2. A new protein factor required for the inactivation of GAD was discovered. Its partial purification and properties are described. The formation of 2 indicates that GAD does not require decarboxylation during the inactivation with serine sulfate. As described in the reaction with chloroalanine Morino, Y. et al. (1974) J. Biol. Chem. 249, 6684, AAT is inactivated over a 10 min period and the absorption maximum at pH 5.4 shifts from 430 nm to 336 nm (1a). The peak shifts again over a period of 20 h to 455 nm (1b), a behavior entirely similar to that reported by Morino et al. for chloroalanine in the presence of 3 M formate. When the 20 h product 1b is reduced with NaBH(,4) and then heated in a boiling water bath, a material identical to a known reduction product of 2 is released. Therefore, the 20 h product 1b consists of 2 bound to the enzyme. Pathways for the formation of the various compounds are proposed. These findings require a reevaluation of the mechanisms of action of many mechanism-based inactivators of PLP-dependent enzymes

Nightmare-Enacting Behavior Responding to Zonisamide in Early Parkinson's Disease

Recently, zonisamide (ZNS) has been approved as a new adjunctive therapy for motor complications of Parkinson's disease (PD). More recently, ZNS was reported to be effective for the management of impulse control behavior in PD, suggesting potential effects on non-motor PD symptoms. Dream enactment associated with aggressive, violent behavior can carry a serious risk of injury to patients, as well as to spouses or caretakers. This report describes a patient with PD who had vivid nightmares and dream-enacting behavior that resolved after treatment with ZNS. The present case raises the question whether ZNS might potentially be effective for the management of vivid nightmares or dream-enacting behavior

On the structures of moss colony in the Yukidori Valley, Langhovde, East Antarctica

The moss vegetation developing in the Yukidori Valley, Langhovde, East Antarctica, was investigated as based on the samples in the vertical cross-section housed as the herbarium specimens to categorize the structure of the moss colony and to determine the specific composition. The vegetation consists of pure colonies of one species, and mixed colonies composed of two or rarely three moss species. Each colony was classified by species composition and degree of unevenness. The active zone, decomposed zone which were seen in the vertical cross-section, and epiphytic condition on the surface such as cyanobacteria and imperfect lichens, and rhizoidal layers in the inside of colony were determined and measured. Furthermore, the relationship between epiphytic condition and the thickness of the pure and mixed colonies was discussed taking account of ecological significances of these structural features

Astrometry of H2_{2}O Masers in Nearby Star-Forming Regions with VERA --- IV. L1448C

We have carried out multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of the 22~GHz H$_{2}$O masers associated with a Class 0 protostar L1448C in the Perseus molecular cloud. The maser features trace the base of collimated bipolar jet driven by one of the infrared counter parts of L1448C named as L1448C(N) or L1448-mm A. We detected possible evidences for apparent acceleration and precession of the jet according to the three-dimensional velocity structure. Based on the phase-referencing VLBI astrometry, we have successfully detected an annual parallax of the H$_{2}$O maser in L1448C to be 4.31$\pm$0.33~milliarcseconds (mas) which corresponds to a distance of 232$\pm$18~pc from the Sun. The present result is in good agreement with that of another H$_{2}$O maser source NGC~1333 SVS13A in the Perseus molecular cloud, 235~pc. It is also consistent with the photometric distance, 220~pc. Thus, the distance to the western part of the Perseus molecular cloud complex would be constrained to be about 235~pc rather than the larger value, 300~pc, previously reported.Comment: 15 pages, 5 figures, accepted for publication in PAS