Biosynthesis of curdlan from culture media containing 13C-labeled glucose as the carbon source

✍ Scribed by Akira Kai; Tatsuya Ishino; Takaaki Arashida; Kenichi Hatanaka; Toshihiro Akaike; Kei Matsuzaki; Yutaro Kaneko; Toru Mimura

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 485 KB
• Volume: 240
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(93)84180-e

✦ Synopsis

C-Labeled curdlans were biosynthesized by Agrobacterium sp. (ATCC 31749) from culture media cantaining o-(l-'3C)glucose, o-(6-t3C)glucose, or o-(2-13C)glucose as the carbon source, and their structures were analyzed by 'sC NMR spectroscopy. The labeling was mainly found in the original position, that is, C-l, C-6, or C-2, indicating direct polymerization of introduced glucose. In addition, C-3 in curdlan obtained from o-(l-'3C)glucose, C-l in curdlan obtained from o-(6-"C)glucose, and C-l and C-3 in curdlan obtained from o-(2-t3)glucose were labeled. From analysis of this labeling, the biosynthesis of curdlan was interpreted as involving five routes: (I) direct synthesis from glucose; (2) rearrangement (l-13C + 3-13C); and ( 3) isomerization (6-13C + 1-13C) of cleaved trioses by the Embden-Meyerhof pathway, followed by neogenesis of glucose and formation of curdlan; (4) from fructose 6-phosphate formed in the pentose cycle (2-13C + l-t3C, 3-t3C); and (5) neogenesis of glucose from fragments produced in various pathways of glycolysis. The t3C-labeling at C-6 and C-2 in the starting glucoses is well preserved in the C-6 carbon and the C-l to C-3 carbons, respectively, in the curdlan produced.