DEGRADATION OF PYRUVATE BY MICROCOCCUS LACTILYTICUS III

Abstract

AND N. G. MCCORMICK. Degradation of pyruvate by Micrococcus lactilyticus. III. Properties and cofactor requirements of the carbon dioxide-exchange reaction. J. Bacteriol. 85:382-393. 1963.-At an acid pH, extracts of Micrococcus lactilyticus (Veillonella alcalescens) catalyze the oxidative decarboxylation of pyruvate to carbon dioxide, hydrogen, and acetyl phosphate, and the rapid exchange of carbon dioxide into the carboxvl group of pyruvate. These reactions take place only under anaerobic conditions and require phosphate (or arsenate), a reducing agent, diphosphothiamine, coenzyme A, an electron acceptor (ferredoxin, flavins, dyes, or certain inorganic anions), and a divalent cation (Co++ > Mni > Mg+ > Fe++). High concentrations of coenzyme A and electron acceptors stimulate pyruvate breakdown but inhibit CO2 exchange. Exchange is also inhibited by p-chloromercuribenzoate but not by arsenite. Extracts rapidly lose the ability to mediate the exchange reaction after passage through diethylaminoethylor triethylaminoethyl-cellulose or Dowex-1; this loss in activity may be prevented by adding a reducing agent and the above cofactors. The exchange of CO2 and formate by M. lactilyticus is compared. Strict anaerobes such as Clostridium butyricum (Wolfe and O'Kane, 1953), Micrococcus lactilyticus (Whiteley and Ordal, 1957), C. saccharobutyricum (Delavier-Klutchko, 1959), and Micrococcus LC (Peel, 1960) are able to degrade pyruvate to acetate, carbon dioxide, and hydrogen. This overall reaction (equation 1) requires phosphate and a slightly acid pH, and involves a pyruvate-acetate + CO2 + H2 (1)

Photobiological Production of Hydrogen: A Solar Energy Conversion Option

“…(A "reversible" hydrogenase functions both in the uptake and evolution direction -in vivo.) In these types of organisms the oxidative decarboxylation of pyruvate reduces an iron-sulfur carrier, ferredoxin (Mortensonet al, 1962 and, and the reduced ferredoxin in turn reduces hydrogenase (Valentineet al, 1963;Whiteley and McCormick, 1963;Nakos and Mortenson, 1971).…”

Pyruvate metabolism by aminopterin-inhibited Aerobacter aerogenes

“…Deibel & Niven, 1964), require thiamine pyrophosphate, specific exchange occurs between the C1 compound and the carboxyl group of pyruvate. Whiteley & McCormick (1963) have proposed a sequence of reactions for the alkaline degradation of pyruvate, the initial steps of which are as follows:…”