L-Malate Oxidation bytheElectron Transport Fraction ofAzotobacter vinelandii

withmolecular 02astheterminal electron acceptor. D-Malate wasnotoxidized, butL-malate wasoxidized tooxalacetate. Phenazine methosulfate (PMS), vitamin K3,K3Fe(CN)6, nitro bluetetrazolium, anddichloioindophenol allserved asgoodterminal electron acceptors fortheL-malate oxidoreductase. Cytochrome cwasapoorelectron acceptor. Extensive studies onthe L-malate oxidase andPMS andK3reductases revealed thatallwerestimulated specifically byflavine adenine dinucleotide andnonspecifically bydi-ortrivalent cations, i.e., Ca++, Ba+,Mn+,Mg+,Fe+++, Ni++, andAl+++. Allthese activities weremarkedly sensitive toethylenediaminetetraacetate (EDTA). TheV,rax values