PYROPHOSPHATASE ACTIVITY OF BACILLUS MEGATERIUM SPORE AND VEGETATIVE CELL EXTRACTS

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Abstract
An inorganic pyrophosphatase was demonstrated in water ex-tracts of spores of B. megaterium. The enzyme is specific for hydrol-ysis of inorganic pyrophosphate, requires Mn++ for activation, and is protected by Mn++ against heat inactivation. The extracted enzyme is heat-labile, but in intact spores it is heat-stable. Metal activation and pH data suggest that more than a single pyrophosphatase is active both in spores and in vegetative cells. As spores germinate and develop into vegetative cells, the Mn++-activated enzyme undergoes progressive quantitative and qualitative changes, decreasing in amount and becoming less sensitive to heat. The enzyme extracted from vegetative cells exhibits none of the Mn++ requirement for activation shown by extract of spores; the need for Mn++ for protection of the enzyme against heat-inactivation decreases as the spores develop into vegetative cells. Furthermore, the predominant Mn++-activated spore pyrophosphatase, with optimal activity near neutrality, is almost completely supplanted by a Co++-activated vegetative cell pyrophos-phatase with optimal activity near pH 5. Mn++-activated pyrophos-phatase may be involved in spore germination. Extracts of spores whose potential for germination has been increased by sublethal heating (50-60[degree] for 5 to 15 minutes) always have greater pyrophos-phatase activity than do extracts of unheated spores.