Incorporation of 8 succinate per mol nickel into factors F430 by Methanobacterium thermoautotrophicum

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Abstract
Factors F430 from methanogenic bacteria have recently been shown to contain nickel and it has been speculated that they may have a nickel tetrapyrrole structure. This assumption was tested by determining whether succinate is incorporated by growing Methanobacterium thermoautotrophicum into three factors F430. Succinate is assimilated by Methanobacterium thermoautotrophicum into the amino acids glutamate, arginine and proline and into tetrapyrroles rather than other cell components. It was found that per mol nickel 8–9 mol of succinate were incorporated into the three factors F430 which is the amount predicted for a tetrapyrrole structure. Since the three factors F430 only contained significant amounts of glutamate rather than arginine or proline, the incorporation data suggest that factors F430 are nickel tetrapyrrole compounds. Spectral properties of the three factors F430, apparent molecular weights, and the absence of phosphor in these compounds are also described.