title: Structure of component B (7-mercaptoheptanoylthreonine phosphate) of the methylcoenzyme M methylreductase system of Methanobacterium thermoautotrophicum.
abstract: Component B, the heat-stable low-molecular-weight cofactor required for methane production by dialyzed cell-free extracts of Methanobacterium thermoautotrophicum, has been purified to homogeneity and its structure assigned. Results of low-resolution fast-atom-bombardment and field-desorption mass spectrometry indicated a molecular weight of 419, and high-resolution fast-atom-bombardment mass spectrometry agreed with the molecular formula C13H26NO8PS2. Evidence from fast-atom-bombardment and field-desorption mass spectrometry and 360-MHz 1H NMR in deuterium oxide argued that the compound was isolated as a mixed disulfide with 2-mercaptoethanol; so the proposed elemental formula of the free acid, free thiol would be C11H22NO7PS (molecular weight, 343). The proposed structure for an active form of the coenzyme is 7-mercaptoheptanoylthreonine phosphate.
mesh_terms: D000577:Amides / Q000302:isolation & purification; D019605:Euryarchaeota / Q000201:enzymology*; D005227:Fatty Acids / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015080:Mesna / Q000032:analysis / Q000378:metabolism; D010088:Oxidoreductases / Q000032:analysis / Q000378:metabolism*; D010769:Phosphothreonine / Q000031:analogs & derivatives* / Q000302:isolation & purification; D013438:Sulfhydryl Compounds / Q000302:isolation & purification*; D013912:Threonine / Q000031:analogs & derivatives*
chemical_list: D000577:Amides; D005227:Fatty Acids; D013438:Sulfhydryl Compounds; C049349:7-mercaptoheptanoylthreonine phosphate; D010769:Phosphothreonine; D013912:Threonine; D010088:Oxidoreductases; C021572:methyl coenzyme M reductase; D015080:Mesna