Food labeling: health claims; dietary noncariogenic carbohydrate sweeteners and dental caries. Final rule.
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The Food and Drug Administration (FDA) is adopting as a final rule, without change, the provisions of the interim final rule that amended the regulation authorizing a health claim on noncariogenic carbohydrate sweeteners and dental caries, i.e., tooth decay, to include isomaltulose as a substance eligible for the health claim. FDA is taking this action to complete the rulemaking initiated with the interim final rule. (+info)
Palatinose and oleic acid act together to prevent pancreatic islet disruption in nondiabetic obese Zucker rats.
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We showed previously that 8-wk consumption of a diet containing palatinose (P, a slowly-absorbed sucrose analogue) and oleic acid (O) ameliorates but a diet containing sucrose (S) and linoleic acid (L) aggravates metabolic abnormalities in Zucker fatty (fa/fa) rats. In this study, we aimed to identify early changes in metabolism in rats induced by certain combinations of carbohydrates and fatty acids. Specifically, male Zucker fatty rats were fed an isocaloric diet containing various combinations of carbohydrates (P; S) and fatty acids (O; L). After 4 wk, no significant differences in body weight, visceral fat mass, plasma parameters (glucose, insulin, lipids, and adipokines), hepatic adiposity and gene expression, and adipose inflammation were observed between dietary groups. In contrast, pancreatic islets of palatinose-fed (PO and PL) rats were smaller and less fibrotic than sucrose-fed (SO and SL) rats. The abnormal alpha-cell distribution and sporadic staining of active caspase-3 common to islets of linoleic-acid-fed rats were not observed in oleic-acid-fed (PO and SO) rats. Accordingly, progressive beta-cell loss was seen in SL rats, but not in PO rats. These findings suggest that pancreatic islets may be initial sites that translate the effects of different combinations of dietary carbohydrates and fats into metabolic changes. (+info)
Inducer-dependent nuclear localization of a Zn(II)(2)Cys(6) transcriptional activator, AmyR, in Aspergillus nidulans.
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AmyR is a Zn(II)(2)Cys(6) transcriptional activator that regulates expression of the amylolytic genes in Aspergillus species. Subcellular localization studies of GFP-fused AmyR in A. nidulans revealed that the fusion protein preferentially localized to the nucleus in response to isomaltose, the physiological inducer of the amylolytic genes. The C-terminal domains of AmyR, designated MH3 (residues 419-496) and MH4 (residues 516-542), were essential for sensing the inducing stimulus and regulating the subcellular localization. The MH2 domain (residues 234-375) located in the middle of AmyR was required for transcriptional activation of the target genes, and the nuclear localization signals were identified within the N-terminal Zn(II)(2)Cys(6) DNA binding motif. (+info)
Structural determinants of product specificity of sucrose isomerases.
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Gene cloning, protein characterization, and alteration of product selectivity for the trehalulose hydrolase and trehalulose synthase from "Pseudomonas mesoacidophila" MX-45.
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Surfactant protein D is a divalent cation-dependent carbohydrate-binding protein.
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Surfactant protein D (SP-D, CP4) is a collagenous surfactant-associated glycoprotein synthesized by lung type II epithelial cells. SP-D can be selectively and efficiently eluted from isolated rat surfactant with glucose, maltose, and certain other saccharides. We therefore examined the ability of the purified protein to interact with carbohydrates in vitro. Saccharide-substituted bovine serum albumins (BSA neoglycoproteins) were adsorbed to plastic wells, and binding of purified SP-D was quantified with monospecific antibodies to SP-D using an indirect immunoassay. SP-D showed specific calcium-dependent binding to alpha-D-glucosidophenyl isothiocyanate-BSA and maltosyl-BSA, but negligible binding to beta-D-glucosidophenyl isothiocyanate-BSA or unconjugated BSA. The most efficient inhibitors of SP-D binding were alpha-glucosyl-containing saccharides (e.g. isomaltose, maltose, malotriose). SP-D showed quantitative binding to maltosyl-agarose and was specifically eluted with maltose or EDTA. High affinity binding to maltosyl-BSA was also demonstrated using a solution-phase polyethylene glycol precipitation assay. These studies demonstrate that SP-D is a calcium dependent lectin-like protein and that the association of SP-D with surfactant is mediated by carbohydrate-dependent interactions with specificity for alpha-glucosyl residues. (+info)
Characterization of the product of the gtfS gene of Streptococcus downei, a primer-independent enzyme synthesizing oligo-isomaltosaccharides.
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The gtfS gene, coding for a glucosyltransferase which synthesizes water-soluble glucan and previously cloned from Streptococcus downei strain MFe28 (mutans serotype h) into a bacteriophage vector, was subcloned into a plasmid vector. The gtfS gene products expressed in Escherichia coli were compared to the primer-independent, oligo-isomaltosaccharide synthase in Streptococcus sobrinus strain AHT (mutans serotype g) and shown to resemble it closely in molecular mass, isoelectric point, immunological properties, optimum pH and Km values. The glucans produced from sucrose by the gtfS gene products are alpha-1,6-linked linear oligo-isomaltosaccharides without any branching sites. A similar gtfS gene was also detected on chromosomal DNA from S. sobrinus strain AHT. (+info)