Isolation and Properties of a Fluorescent Compound, Factor 420 , from Methanobacterium Strain M.o.H

Abstract

A new fluorescent compound, factor 420 (F 420 ), which is involved in the hydrogen metabolism of hydrogen-grown Methanobacterium strain M.o.H. has been isolated and purified. Acid hydrolysis of this compound with 6 m HCl for 24 hr releases a ninhydrin-positive compound (glutamic acid), an acid-stable chromophore, phosphate, and an ether-soluble phenolic component. Factor 420 may be reduced by either sodium dithionite or sodium borohydride at p H 7.3 with concomitant loss of its fluorescence and its major absorption peak at 420 nm. Crude cell-free extracts of strain M.o.H. reduce F 420 only under a hydrogen atmosphere. F 420 is photolabile aerobically in neutral and basic solutions, whereas the acid-stable chromophore is not photolabile under these conditions. An approximate molecular weight of 630 ± 8% for F 420 was determined by Sephadex G-25 chromatography. At the present time, F 420 is proposed as a trivial name for the unknown fluorescent compound because of its strong absorption maximum of 420 nm at p H 7.