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At temperatures below T(g), amorphous salicin had relatively greater molecular mobility than amorphous indomethacin. This difference in the molecular mobility of the two compounds is correlated with their crystallization behavior. Solid-state (13)C NMR provides valuable information on the physical stability of amorphous pharmaceuticals.

Complex type N-glycosides of commercial bovine fetuin preparations from pooled fetal calf serum have been shown to contain comparable amounts of Gal4,4,4TRI (see structure A below) and Gal4,4,3TRI (structure B) as major asialo-structures. To investigate whether there is a clear genetic specificity for synthesis of these oligosaccharides, N-glycosides from two preparations of bovine fetuin, each from a single calf, were examined. Both of these structures were present in each calf, and there was only a subtle quantitative difference in the ratio of these two structures between the calves. Thus, a specific galactosyltransferase, presumably required for the biosynthesis of the Gal4,4,3TRI structure, may exist in both of these individual calves. Comparison of fetuin N-glycosides was also extended to sheep, pig, and human alpha 2-HS-glycoprotein, the human counterpart of bovine fetuin, using high-pH anion-exchange chromatography of the reducing oligosaccharides as well as HPLC of their pyridinylamino derivatives. The N-glycosides of ovine fetuin also have both Gal4,4,4TRI and Gal4,4,3TRI structures in a ratio similar to that of bovine fetuin. However, the major N-glycoside of porcine fetuin is of a fucosyl biantennary complex type structure (structure C below) and human alpha 2-HS-glycoprotein has an N-glycoside which is almost exclusively a nonfucosylated biantennary structure (structure D). This species-specific presence of N-glycosides of fetuins and comparison with N-glycosides of other glycoproteins suggest that the polypeptide sequence of a glycoprotein may affect its N-glycan structure by regulating the activity of specific glycosyltransferases. [formula: see text]

A new peptide antibiotic, aibellin, that had the efficiency enhancing activity on rumen fermentation, was isolated from the culture broth of the fungus, Verticimonosporium ellipticum D 1 528, and its primary structure was elucidated from spectrometric analysis and chemical degradation.Aibellin is a 20-residue peptaibol, and it has a unique structural feature in the novel C-terminal amino alcohol. Moreover, aibellin is the first peptaibol that possesses two acidic amino acids in the C-terminal region and a Phe residue in the middle of the sequence.In ruminants, the positive correlation between an increase in feed conversion and enhanced propionate production in the rumenafter the treatment of ionophore antibiotics such as monensin and lasalocid has been reported1~3). These antibiotics enhance propionate production and reduce methanogenesis, thus leading to greater efficiency of energy metabolism in ruminant animals3'40.During our search for novel ruminant growth performance enhancers from microbial sources using an in vitro rumenfermentation system, a newlinear peptide antibiotic, aibellin, was found in the culture broth of the fungus Verticimonosporium ellipticum D1528. Aibellin was found to enhance propionate production and to reduce methanogenesis by rumen microorganisms5).In this paper, we report the isolation and structural elucidation of aibellin. Aibellin had structural

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