LACTATE AND GLUCOSE OXIDATION SYSTEMS IN ACETOBACTER SUBOXYDANS

1. From a strain of Acetobacter suboxydans, a glucose and a lacticenzyme were obtained in cell-free states. The lactic enzymeshows as strong activity as the glucose enzyme but is more stablethan the latter toward various purification procedures: bothare sensitive to high temperature treatment. Activities of thetwo enzymes and the MICHAELIS constants of the glucose enzymewere determined under both aerobic and anaerobic conditions.
2. Carbon monoxide inhibits the oxygen-uptake in both glucoseandlactate oxidation. WARBURG's distribution constant for lactateoxidation is 6.7. These results suggest the participation ofan heme enzyme in the oxidation system.
3. Effects of copperreagents, narcotics and PCMB were also examined.
4. The dehydrogenaseactivities (reduction of dye) of the enzymesare more sensitiveto high temperature than the correspondingactivities in oxygen-uptake.
5. By combining a dehydrogenase preparation which has lost itsoxygen-absorbing activity through acetone treatment, with aheated extract, a partial recovery of oxygen-uptake can be realizedin lactate oxidation.
6. L-Cysteine is utilized as hydrogen donorby the bacterium. Thisoxidative reaction, unlike the oxidationof lactate, is notinhibited by surface active reagents.

(Received May 16, 1960; )     

COMPONENTS OF THE ELECTRON-TRANSFERRING SYSTEM IN ACETOBACTER SUBOXYDANS AND RECONSTRUCTION OF THE LACTATE OXIDATION SYSTEM

1. Cytochromes a₁⁵⁹⁰, b⁵⁶⁰, c₁⁵⁵⁴ and c₁⁵⁵² were isolated andpurifiedfrom a strain of Acetobacter suboxydans. The proceduresusedwere described in detail.
2. The main cytochrome band at550-560 mµ in intact cellssplitted at liquid air temperatureinto two bands, 551 mµ(strong) and 559 mµ (weak).
3. Optical and physiological properties of the four cytochromeswere investigated. Lactic dehydrogenase activity was found tobe associated with cytochrome c₁⁵⁵⁴. The two c₁-type cytochromes,especially cytochrome c₁⁵⁵⁴, persisted in their reduced formafter the purification through many steps.
4. By some combinationsof isolated components reconstruction ofthe oxygen uptake systemcould be realized.
5. The oxygen-consuming activity of purifiedoxidase preparationswas accelerated by a-tocopherol but notby Emasoll 4130 andTween 80.
6. Some discussions were made onthe nature of terminal oxidase,the role of cytochrome c₁⁵⁵²in the electron-transport system,and persistence of reducedstate of c₁-type cytochromes.
7. A possible scheme of the electron-transferringsystem of Acetobactersuboxydans was presented.

(Received May 16, 1960; )     

THE NASAL APPARATUS IN DIPNOI, WITH SPECIAL REFERENCE TO PROTOPTERUS

An investigation is made of the homology of the nasal apparatus of the Dipnoi, in order to determine whether the posterior naris is homologous with the choana of tetrapods or with the posterior external naris of fishes. The ontogeny of the nasal capsule of Protopterus is described in detail. The nervous and venous systems of tho snout region of Protopterus are also duscrbed. It is found that whereas the pattern of the nervous and vascular systems is very similar in all Dipnoi, the structuro of the nasal capsule in the Lepidosiren-Protopterus stock differs greatly from that of the Neoceratodus stock. the homology of the various components of the depnoan nasal coasule is revised and it is shown that there are no evidences of a direct relationship of the Dipnoi with the tetrapods. It is further concluded that the posterior naris of Dipnoi is homologous with the posterior external naris of fishes.     

STUDIES ON LACTATE CYTOCHROME C REDUCTASES OF YEAST WITH SPECIAL REFERENCE TO ELECTROPHORESIS ON POLYACRYLAMIDE GEL

1. Two lactate dehydrogenases, L(+)- and D(–)- lactate cytochromec reductase, were extracted from the baker's yeast after disintegrationof the cells by a FRENCH press. They are separated by electrophoresison polyacrylamide gel and their activities were compared bycolor density of formazan, the reduction product of nitrobluetetrazolium.
2. The ratio of L-lactate cytochrome c reductaseactivity to D-lactatecytochrome c reductase activity variedto a great extent, dependingon culture conditions. L-Lactatecytochrome c reductase waspredominant in resting cells; thereverse was the case withcells in early exponential stage ofthe growth.
3. When the cells in exponential stage of growthwere aerated withoutnitrogen source, there occurred an intensiveincrease of L-lactatecytochrome c reductase, accompanied bythe decrease of D-lactatecytochrome c reductase.
4. Effectsof inhibitors on the activity ratio of these two enzymeswereinvestigated. o-Phenanthroline, dinitrophenol, sodium azide,chloramphenicol, British antilewisite and antimycin A favored,in this order, the formation of L-lactate cytochrome c reductase.

(Received August 18, 1966; )