No abstract

The bifunctional reagent N-(4-azidobenzoyl)-putrescine was synthesized and covalently bound to rabbit skeletal muscle actin. The incorporation was mediated by guinea pig liver transglutaminase under conditions similar to those described by Takashi (1988, Biochemistry 27, 938-943); up to 0.5 M/M were incorporated into G-actin, whereas F-actin was refractory to incorporation. Peptide fractionation showed that at least 90% of the label was bound to Gln-41. The labeled G-actin was polymerized, and irradiation of the F-actin led to covalent intermolecular cross-linking. A cross-linked peptide complex was isolated from a tryptic digest of the cross-linked actin in which digestion was limited to arginine; sequence analysis as well as mass spectrometry indicated that the linked peptides contained residues 40-62 and residues 96-116, and that the actual cross-link was between Gln-41 and Lys-113. Thus the y-carboxyl group of Gln-41 must be within 10.7 A of the side chain (probably the amino group) of Lys-I13 in an adjacent actin monomer. In the atomic model for F-actin proposed by Holmes et al. (1990, Nuture 347, 44-49), the a-carbons of these residues in adjacent monomers along the two-start helices are sufficiently close to permit cross-linking of their side chains, and, pending atomic resolution of the side chains, the results presented here seem to support the proposed model.

We report a facile procedure to synthesize racemic modafinil (diphenylmethylsulfinylacetamide), which is now being used in pharmacotherapy, and its achiral oxidized derivative (diphenylmethylsulfonyl acetamide). Modafinil is of interest more than for its potential anti-narcoleptic activity. It has also been reported to have neuroprotective properties and may potentially be effective in the enhancement of vigilance and cognitive performance. Finally, it may also protect from subclinical seizures that have been implicated as causative factors in autistic spectrum disorders and other neurodegenerative conditions. This agent can now be synthesized simply and in larger amounts than previously, making it more readily available for testing in various research modalities. The described procedure also lends itself to production of several other amides of potential interest. We are currently in the process of synthesizing and testing several new derivatives in this series. The anticonvulsant properties of modafinil and its sulfone derivative have not previously been extensively described in the literature. It may be of interest to note that the oxidized derivative of modafinil is also nontoxic and almost as effective as an anticonvulsant as the parent.

Ethyl 4-(p-Tolylsulfonyl)-3-triphenylphosphoranylbutanoate (11).-A mixture of 197 mg of p-tolylsulfonylaziridine,® 348 mg of 1, and 25 ml of dry toluene was refluxed for 15 min. On cooling, a white solid, mp 240-260°, precipitated and was filtered. Evaporation of the filtrate gave 166 mg of crude 11. Four recrystallizations from 95% ethanol gave 11, mp 184-186°.

The narcotic antagonists naltrexone (1a) and naloxone (2a) were stereospecifically reduced to the corresponding 6beta-hydroxy epimers 1b and 2b, respectively, with formamidinesulfinic acid in an aqueous alkaline medium. The reaction products were obtained with no detectable quantity of the 6alpha epimers 1c and 2c. The products 1b and 2b were formed in yields of 88.5 and 40%, respectively, and characterized by spectral methods. Compared to 1a and 2a, the stereospecific reduction products 1b and 2b and their 6alpha epimers 1c and 2c are all significantly less potent as narcotic antagonists in mice. Only 1c and 2c also possess antinociceptive activity.