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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extracellular enzymatic activity of a mixed culture of anaerobic marine bacteria enriched on pullulan [alpha(1,6)-linked maltotriose units] was directly assessed with a combination of gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (NMR). Hydrolysis products of pullulan were separated by GPC into three fractions with molecular weights of > or = 10,000, approximately 5,000, and < or = 1,200. NMR spectra of these fractions demonstrated that pullulan was rapidly and specifically hydrolyzed at alpha(1,6) linkages by pullulanase enzymes, most likely type II pullulanase. Although isolated pullulanase enzymes have been shown to hydrolyze pullulan completely to maltotriose (S. H. Brown, H. R. Costantino, and R. M. Kelly, Appl. Environ. Microbiol. 56:1985-1991, 1990; M. Klingeberg, H. Hippe, and G. Antranikian, FEMS Microbiol. Lett. 69:145-152, 1990; R. Koch, P. Zablowski, A. Spreinat, and G. Antranikian, FEMS Microbiol. Lett. 71:21-26, 1990), the smallest carbohydrate detected in the bacterial cultures consisted of two maltotriose units linked through one alpha(1,6) linkage. Either the final hydrolysis step was closely linked to substrate uptake, or specialized porins similar to maltoporin might permit direct transport of large oligosaccharides into the bacterial cell. This is the first report of pullulanase activity among mesophilic marine bacteria. The combination of GPC and NMR could easily be used to assess other types of extracellular enzyme activity in bacterial cultures.
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PMID:Extracellular enzyme activity in anaerobic bacterial cultures: evidence of pullulanase activity among mesophilic marine bacteria. 816 Nov 77

Brown rice of sugary-1 mutants has a wrinkled character because of the presence of phytoglycogen instead of starch in the inner part of the endosperm. Because the wrinkled phenotype was used as a sole selection marker for progeny of the sugary-1 strain, identification of mutant seeds with improved appearance is very difficult. We found that sugary-1 varieties contained not only phytoglycogen but also free glucose in the endosperm, and these were positively correlated. In the segregated F2 seeds that resulted from crossing Hokurikutou237 (sugary-1) and Koshihikari strains, glucose and phytoglycogen were also significantly correlated. Thus, we identified new sugary types with improved appearance from these progeny using glucose measurements. The F4 seeds of the improved strain had moderate phytoglycogen contents and seed germination characteristics. Native-PAGE showed that pullulanase activity in the improved strain increased in developing seeds compared with Hokurikutou237, although isoamylase activity was extremely low and similar to that in sugary-1 types. The new selection method in this study efficiently aids the development of improved sugary rice types that lack the wrinkled phenotype.
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PMID:Development of a new selection method and quality improvement of sugary-1 rice mutants. 2475 85