Isolation and characterization of the carbohydrate moiety bound to N-7-mercaptoheptanoyl-O-threonine phosphate |
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| Authors: | F.D. Sauer B.A. Blackwell J.K.G. Kramer B.J. Marsden |
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| Affiliation: | Animal Research Centre, Ottawa, Ontario, Canada;Plant Research Centre, Research Branch, Agriculture Canada, Ottawa, Ontario, Canada;National Research Council, Ottawa, Ontario, Canada |
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| Abstract: | Abstract Component B ( N -7-mercaptoheptanoyl-threonine- O -3-phosphate) (HS-HTP) which is an absolute requirement in the methylcoenzyme M methylreductase reaction was found to be part of a complex UDP-disaccharide when isolated carefully from cell-free supernant of Methanobacterium thermoautotrophicum . The site of attachment of HS-HTP to the UDP-disaccharide was through a carboxylic-phosphoric anhydride linkage of the C-6 mannosaminuronic acid to the phosphate group in HS-HTP. This bond is quite labile and this may account for the fact that the intact molecule, called methyl reducing factor (MRF) was not isolated previously. The structure of MRF was determined by combined fast atom bombardment mass spectrometry and 1H-, 13C-, and 31P-NMR spectroscopy and assigned as: uridine 5'-[ N -7-mercaptoheptanoyl- O -3-phosphothreonine(2-acetamido-2-deoxy- β -mannopyranuronosyl)acid anhydride]-(1 → 4)- O -2-acetamido-2-deoxy α -glucopyranosyl diphosphate. |
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| Keywords: | Methanobacterium thermoautotrophicum Methyl reducing factor Structure Function |
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