CARBOHYDRATE OXIDATION BY PSEUDOMONAS FLUORESCENS

II. MECHANISM OF HEXOSE PHOSPHATE OXIDATION*

BY W. A. WOOD AND R. F. SCHWERDT

(From the Laboratory of Bacteriology, Department of Dairy Science, University of Illinois, Urbana, Illinois)

(Received for publication, August 3, 1953)

Glucose oxidation by Pseudomonas Jluorescens (1) and Pseudomonas aeruginosa (2) has been shown to proceed via gluconate to 2-ketogluconate without the involvement of phosphorylated intermediates. 2-Ketoglu- conate is oxidized further in growing cultures (3) and resting cell suspensions (4), but attempts to obtain dried cell preparations or cell-free extracts which oxidize 2-ketogluconate have been successful only with Acetobacter melanogenum, in which case 2,5-diketogluconate was formed (5).

The rapid oxidation of glucose-l-phosphate (G-l-P), glucose-6-phos- phate (G-6-P), and fructose-6-phosphate (F-6-P) by extracts of P. Jluores- tens, observed by Wood and Schwerdt (I), has suggested the existence of other pathways of carbohydrate oxidation in addition to direct oxidation via gluconate and 2-ketogluconate. In addition, the presence of phospho- glucomutase, phosphohexose isomerase, and hexokinase in Pseudomonas putrefaciens and enzymes converting 6-phosphogluconate to pyruvate and triose phosphate in Pseudomonas saccharophila have been demonstrated by Klein and Doudoroff (6) and Entner and Doudoroff (7). These findings further indicate the presence of oxidative pathways involving phosphory- lated intermediates in the pseudomonads. In the latter two organisms, however, the oxidation of glucose to gluconate and 2-ketogluconate ap- parently does not occur.

In view of the apparent multiplicity of oxidative pathways in these or- ganisms, further experiments have been undertaken to elucidate the mech- anism of hexose phosphate oxidation. The data to be presented indicate the existence of alternative routes of phosphate ester metabolism in P. Jluorescens. In the oxidative (hexose monophosphate) pathway, 6-phos- phogluconate undergoes both an oxidation and a non-oxidative split to pyruvate and triose phosphate. The presence of several glycolytic en-

* This investigation was supported in part by a grant-in-aid from the National Science Foundation. A preliminary account of this work was presented at a sym- posium on ‘Some aspects of carbohydrate metabolism,” Oak Ridge, Tennessee, 1952.

625

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

626 MECHANISM OF HEXOSE PHOSPHATE OXIDATION

zymes has been demonstrated; the complete glycolytic system, however, does not participate in hexose phosphate oxidation.

Methods

Cell-free extracts of P. Jluorescens, A3.12, containing approximately 35 mg. of protein per ml. were prepared by sonic treatment of aqueous bac- terial suspensions, as described previously (1).

Xubstrates-Crystalline barium glucose-6-phosphate heptahydrate (98 to 100 per cent pure) was prepared enzymatically from starch with potato phosphorylase and rabbit muscle phosphoglucomutasel or from crude bar- ium fructose-6-phosphate with dialyzed rabbit muscle extract (8). Barium ribosed-phosphate (R-5-P), having the theoretical pentose analysis and chromatographically homogeneous, was obtained from the Schwarz Labo- ratories. Barium ribulose-5-phosphate was prepared by Dr. B. L. Horec- ker. Triphosphopyridine nucleotide (TPN), 80 per cent pure, was ob- tained from the Sigma Chemical Company. Reduced diphosphopyridine nucleotide (DPNH) was prepared either by the method of Ohlmeyer (9) or by that of Lehninger (10). Glyceraldehyde-3-phosphate (G-3-P) was prepared from nn-glyceraldehyde-1-bromide-3-phosphoric acid (dimeric), obtained from the Concord Laboratories, Cambridge, Massachusetts, by neutralization with sodium hydroxide (11). Sedoheptulose and sedohep- tulosan were supplied by Dr. N. K. Richtmyer.

Enzymes-Lactic dehydrogenase was prepared by the method of Straub (12). The alkaline phosphatase (13) was obtained from Armour and Com- pany. Glucose-gphosphate dehydrogenase (0.5 unit per mg. of protein) and 6-phosphogluconate (6-PG) dehydrogenase (15.2 units per mg. of protein) and the other preparations used were described previously (1).

Determinations-Metabolic gas exchange was measured in the Warburg respirometer by conventional methods. Glucose-6-phosphate and 6-phos- phogluconate were determined in a Beckman model DU spectrophotometer with quartz micro cuvettes of 0.5 ml. capacity, according to the method of Horecker and Smyrniotis (14). Pentose and sedoheptulose were deter- mined by a modification of Mejbaum’s procedure (15). Duponol was added to stabilize the color produced by sedoheptulose and sedoheptulosan. Triose phosphate was estimated as alkali-labile phosphate (16). Pyruvate was measured enzymatically with lactic dehydrogenase and DPNH as the decrease in optical density at 340 rnp, or calorimetrically by the double ex- traction procedure of Friedemann and Haugen (17). Protein was esti- mated by the biuret procedure of Robinson and Hogden (18).

1 Wood, W. A., unpublished procedure.

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. WOOD AND R. F. SCHWERDT 627

Results

As shown in Fig. 1, extracts of P. Jluorescens, in addition to oxidizing glucose and gluconate, rapidly oxidized a number of phosphate esters in- volved in the glycolytic and the hexose monophosphate systems. G-l-P and G-6-P were oxidized at equal rates and F-6-P, 6-PG, and R-5-P also were oxidized, but at somewhat slower rates. Fructose-l ,6-diphosphate (F-l, 6-P) was oxidized very slowly. The oxygen consumption with G-6-P continued beyond 7 hours and resulted in 3.5 to 5.5 PM of oxygen uptake per

0 I 2 3 40 I 2 3 4 HOURS

FIG. 1. Oxidation of various substrates by a sonic extract of P. suorescens. The Warburg cups contained approximately 35 mg. of protein, 20 PM of substrate, 100 y of DPN (80 per cent purity), and Verona1 buffer, pH 7, in a fluid volume of 3 ml. Temperature, 37”.

micromole of G-6-P and an R. Q. of 1.1 to 1.35. In these calculations the endogenous values were subtracted. Thus these crude preparations con- tained an intact system capable of oxidizing hexose phosphates essentially to completion.

Glycolytic Enzymes-Table I presents typical rate measurements of sev- eral glycolytic enzymes present in a sonic extract. As previously reported (l), such extracts are devoid of hexokinase. Similarly, phosphohexokin- ase could not be detected. It can be seen from Table I, however, that phos- phoglucomutase, phosphohexose isomerase, aldolase, triosephosphate isom- erase, and G-3-P dehydrogenase were present. The activity of G-3-P dehydrogenase was considerably greater than that of the other glycolytic enzymes tested. The amount of phosphoglucomutase and phosphohexose

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

628 MECHANISM OF HEXOSE PHOSPHATE OXIDATION

isomerase was approximately that reported by Klein and Doudoroff (6) for P. putrefaciens. These findings suggest that the oxidation of G-l-P and F-6-P involves first a conversion to G-6-P, followed by G-6-P oxidation via the hexose monophosphate pathway. The slow rate of F-l, 6-P oxida- tion and the lack of phosphohexokinase eliminate a r&e of the glycolytic pathway in these oxidations.

Glucose-&phosphate and 6-Phosphogluconate Dehydrogenuses-G-6-P and 6-PC oxidation was studied in more detail by measuring pyridine nucleo- tide reduction at 340 rnp (Fig. 2). In contrast to the yeast G-6-P and 6-PG dehydrogenases, rapid reduction of both DPN and TPN occurred.

TABLE I Activity of Glycolytic Enzymes in Extracts of P. Jluorescens

EIlZyIlle

Phosphoglucomutase

Phosphohexose isomer- ase

Hexokinase Phosphohexokinase Aldolase

“ + isomerase Glyceraldehyde-3-phos-

phate dehydrogenase

Substrate

G-l-P ‘<

G-6-P F-6-P Glucose + ATP§ F-6-P + ATP F-1,6-P G-3-P

‘(

Compound measured

G-6-P “

F-6-P G-6-P

“

Triose PO1 F-1,6-P DPNH

Method*

+ A TPNH$ (25)

+ A fructose + A TPNH$ (1) (26) (27) + A fructose (28)

Ratet

4.4 18.5 4.5 7.7 0 0

11.5 12.0

295

* The figures in parentheses refer to the bibliography. t Micromoles per hour per ml. of enzyme (approximately 35 mg. of protein

per ml.). t Excess glucose-g-phosphate dehydrogenase present. $ Adenosinetriphosphate.

In all experiments, the reduction rates with DPN and TPN were of the same order of magnitude, but the reduction with G-6-P was considerably more rapid than with 6-PG.

As shown in Fig. 2, the kinetics of DPN reduction differed markedly from those of TPN with either G-6-P or 6-PG as a substrate in that a marked lag occurred after the reduction was initiated, which was followed by a re- turn to the maximal rate. The length of the lag and the point at which it appeared varied with the preparation. These anomalous kinetics indi- cated the presence of a competing reaction by which DPNH was oxidized. Since neither precipitation with ammonium sulfate nor dialysis abolished the lag, it appeared that metabolic products were not serving as acceptors. However, the DPNH concentration could be reduced sharply, even in the presence of excess G-6-P, by aerating the contents of the cuvettes. The

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. WOOD AND R. F. SCHWERDT I329

fact that DPNH was rapidly oxidized by molecular oxygen, whereas TPNH was not, is shown in Fig. 3. In the presence of excess G-6-P, DPN re- duction was initiated and a lag of about 12 minutes was observed. After reduction was complete, aeration by stirring decreased sharply the DPNH concentration. Following this, reduction again occurred until the DPN was completely reduced. With a limiting G-6-P concentration, only a transient appearance of DPNH was observed. The lag thus reflects’ a period of DPNH oxidation by dissolved oxygen, during which the rates of DPN reduction and DPNH oxidation are equal. After the formation of TPNH by G-6-P in limiting concentration, aeration did not cause TPNH

I DPN AND TPN REDUCTION I I

0.51

ryF--$fq , i 0 IO 20 30

MINUTES

FIG. 2. DPN and TPN reduction by glucose-6-phosphate and 6-phosphogluconate. The quartz micro cuvettes (2. = 1 cm.) contained 0.015 ml. of sonic extract, 0.05 ml. of Verona1 buffer, pH 7,0.04 PM of DPN or 0.03 pM of TPN, 3.2 pM of G-6-P or 6-PG, and water to 0.5 ml.

oxidation. However, upon the addition of DPN to the same cuvette, a rapid oxidation of TPNH occurred. The presence of a flavoprotein DPNH dehydrogenase was indicated by the reduction of 2,3,5-triphenyltetra- zolium chloride to the red formazan in the presence of G-6-P and DPN, or with DPNH alone. The addition of TPN and G-6-P to dialyzed ex- tracts resulted in a very slow rate of dye reduction.

The G-6-P and 6-PC dehydrogenases were separated by an ammonium sulfate fractionation which separated the particles from the soluble pro- teins. Glucose-6-phosphate dehydrogenase, as measured by both DPN and TPN reduction, was found exclusively in the particle fraction which was precipitated by 0.5 volume of saturated neutral ammonium sulfate. A lag during DPN reduction similar to that exhibited by crude extracts was observed. This fraction also contained the glucose- and gluconate-oxi-

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

630 MECHANISM OF HEXOSE PHOSPHATE OXIDATION

dizing system as well as the cytochrome carriers (1). The 6-PG dehy- drogenase was found exclusively in the soluble protein fraction precipitated by an additional 2.5 volumes of saturated ammonium sulfate. Since the cytochrome carriers are found exclusively in the particle fraction, no in- flection was observed during DPN reduction by the soluble fraction.

6-Phosphogluconate Degradation-A measurement of the stoichiometry of 6-PG utilization showed that two pathways were involved (Table II). The enzyme was incubated with 6-PG (12.5 PM per ml.), hydrazine (112

DPN.H AND TPN.H OXIDATION fix I I I I I

1 0 MINUTES

FIG. 3. DPNH and TPNH oxidation by a sonic extract of P. jhorescens. The cuvettes contained 0.15 ml. of sonic extract, 5 pM of MgC12, 12 PM of glycylglycine buffer, pH 7.4, and 0.05 NM of TPN or DPN. 0.02 PM (solid circles) or 1.6 PM (open circles) of G-6-P was added. The volume was 0.5 ml. The reaction mixture was aerated by vigorous stirring. DPN was added as indicated.

FM per ml.) to fix triose phosphate, and sodium arsenite (2 PM per ml.) to inhibit pyruvate utilization. 6-PG, triose phosphate (alkali-labile P), pyruvate, and pentose determinations were run on the trichloroacetic acid extract at 0 and 30 minutes. Approximately equal amounts of pyruvate and triose phosphate were formed. These products accounted for about 90 per cent of the 6-PG, the remaining 10 per cent being pentose phosphate. In the same interval, 7.7 pM of 23 pM of ribose-5-phosphate were utilized. Neither pyruvate nor triose phosphate accumulated, thereby eliminating ribose-5-phosphate as an intermediate in the reaction. Similarly, the utili- zation of ribulose-5-phosphate did not result in triose phosphate or py- ruvate formation. In many experiments low triose phosphate values were obtained. It is possible that triose phosphate hydrazone formation was

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. WOOD AND R. F. SCHWERDT 631

not complete-and further reactions, such as oxidation or condensation, to form F-l ,6-P occurred.

Owing to the limiting TPN concentration and lack of TPNH oxidation in these extracts, as described above, the amount of pentose formed (Table II) does not reflect the true 6-PG dehydrogenase activity. With another preparation, the rate of 6-PG oxidation by 6-PG dehydrogenase (14) and the rate of 6-PG splitting under optimal conditions2 revealed typical rates of 24 and 144 PM of 6-PG utilized per hour per ml. of extract respectively.

In view of the high G-3-P dehydrogenase activity, DPN reduction in the presence of 6-PG could occur by the action of the 6-PG-splitting system (which forms G-3-P) and G-3-P dehydrogenase. If such were the case, the addition of sodium fluoride, which inhibits the 6-PG-splitting system,

TABLD II 6-Phosphogluconate Metabolism by P. jluorescens Extract

The stoichiometry of 6-phosphogluconate utilization by extracts of P. JEuorescens. A 5 ml. reaction mixture contained 1 ml. of sonic extract, 0.5 ml. of 0.25 M glycyl-

glycine buffer, pH 7.4,l ml. of 6-PC, 100 pM per ml., 1 ml. of 0.56 M hydrazine sulfate (neutralized), and 1.0 ml. of lo+ M sodium arsenite. At 0 and 30 minutes, a 2 ml. aliquot was removed and the reaction stopped with 0.4 ml. of 40 per cent TCA.

Substrate

A p?d in 30 min.

6-PG / Pyruvate 1 &$p Pentose

, None .................................. 0 6-PG,12.5p~ ......................... -8.20 +7.40 +6.22 R-5-P, 23 PM ........................... +0.1 0

+0.08 +0.84 -7.7

or iodoacetate, which inhibits G-3-P dehydrogenase, should abolish DPN reduction. Under the conditions shown in Fig. 2, DPN reduction by both 6-PG and G-3-P occurred. The rate with G-3-P was considerably less than that measured in the presence of cysteine and arsenate (Table I). When 0.02 M sodium fluoride or 10m3 M iodoacetate was present, however, the rate of DPN reduction by 6-PG was not decreased appreciably. From this observation it is evident that the observed DPN reduction by 6-PG does not result from the formation and oxidation of G-3-P, even though the enzymes catalyzing these reactions under other conditions are present.

Pentose Phosphate CJtilization-As already noted, ribulose-5-phosphate and ribose-5-phosphate were degraded, but triose phosphate and pyruvate did not accumulate. The pentose phosphates appeared to be utilized by a system in some ways similar to the combined, purified rat liver pentose-

2 Kovachevich, R., and Wood, W. A., unpublished procedure.

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

632 MECHANISM OF HEXOSE PHOSPHATE OXIDATION

splitting enzyme and aldolase (19) or spinach enzyme (20) studied by Horecker et al. The decrease in pentose phosphate was accompanied by the formation of a compound reacting like sedoheptulose in the orcinol pentose test (19). As shown in Fig. 4, the absorption peak at 680 rnp, characteristic of aldopentoses, disappeared and a broad absorption band of low intensity between 580 and 650 rnp appeared (19). The latter is similar to that produced by 10 y of sedoheptulosan. Sedoheptulose was further identified on chromatograms by the ketoheptulose reagent of Bevenue and Williams (21) after incubation of the reaction mixture with alkaline phos-

RlSoSE-5- PHOSPHATE UTILIZATION

ORCINOL- Fe& REAGENT

~~EDoHEPTuL~SE

400 500 600 700 ..,..,I- I F.1F.711 -..

FIG. 4. Orcinol spectrum after incubation with ribose-5-phosphate. The reac- tion mixture contained 0.4 ml. of crude enzyme, 0.2 ml. of ribose-5-phosphate, 100 FM per ml., and 1.4 ml. of water. 0.5 ml. of the reaction mixture was acidified with 0.1 ml. of 40 per cent trichloroacetic acid and centrifuged. 0.01 ml. of the super- natant solution was assayed for pentose. Sedoheptulosan was used to obtain the spectrum of sedoheptulose.

phatase, deionization with a mixed Dowex 2-Dowex 50 column, and paper chromatography. In acetone-water (9:1), butanol-propionic acid-water (22), and water-saturated phenol, RF values for authentic sedoheptulose and the reaction product were 0.24, 0.27, and 0.43 respectively.

DISCUSSION

Although glucose is oxidized to gluconate and 2-ketogluconate by P. JIuorescens (l), a system for the essentially complete oxidation of hexose phosphates, as well as many glycolytic enzymes, also is present in this or- ganism. The inability to demonstrate the presence of hexokinase, glu- conokinase, and phosphohexokinase is consistent with the predominant, if not the exclusive, utilization of glucose by the direct oxidative pathway

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. WOOD AND R. F. SCHWERDT 633

through gluconate observed with growing cultures (3), dried cell prepara- tions (2), and enzyme preparations (1). In view of the inability to demon- strate glucose or gluconate phosphorylation, the r81e of enzymes attacking phosphorylated intermediates is not evident, however. The phosphoroly- sis of polysaccharides to yield hexose phosphates or a cyclic mechanism for 2-ketogluconate oxidation in which hexose phosphates eventually are in- volved is possible.

The observed reduction of both DPN and TPN in the presence of G-6-P and 6-PG is most easily explained by the combined action of a TPN- specific dehydrogenase and a pyridine nucleotide dehydrogenase (23). The requirement for DPN for TPNH oxidation is considered evidence for the presence of a pyridine nucleotide transhydrogenase. An alternative pos- sibility would be either the presence of a pyridine nucleotide-non-specific dehydrogenase or two dehydrogenases, one specific for DPN, the other for TPN. DeMoss3 has observed the presence of DPN-linked, 6-PG de- hydrogenase in Leuconostoc mesenteroides. Thus, even though a transhy- drogenase is present, other mechanisms of DPN reduction have not been eliminated. An attempt to separate the DPN- and TPN-specific G-6-P dehydrogenase activity has been unsuccessful, since the enzymes are tightly bound to the particles. The repeated precipitation of the particles with ammonium sulfate or by high speed centrifugation has not produced a TPN requirement for DPN reduction, as has been observed by Colowick et al. (23) in cases in which DPN reduction is mediated by pyridine nucleo- tide transhydrogenase.

Alternative pathways of 6-PG metabolism were found in the extracts. A 6-PC dehydrogenase and a system splitting 6-PG to triose phosphate and pyruvate are present. Since 6-PG undergoes a C&3 split relatively faster than it undergoes oxidation, the former reaction appears to be of major importance in this organism. Presumably triose phosphate can be formed by both of the 6-PG-utilizing reactions, however, either directly by the C&3 split, or from pentose phosphate (24). The high triosephosphate dehydrogenase activity in extracts relative to that of the other glycolytic enzymes assayed suggests a major r81e of triose phosphate in hexose phos- phate oxidation in spite of the fact that the glycolytic system as such is not involved.

The formation of sedoheptulose phosphate from ribosed-phosphate or ribulose-5-phosphate by P. JEuorescens, as well as by yeast, liver, and spinach (19), indicates the general importance of this process in carbohy- drate metabolism. At the moment, however, the part this reaction plays in carbohydrate oxidation is obscure.

* DeMoss, R. D., private communication.

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

634 MECHANISM OF HEXOSE PHOSPHATE OXIDATION

The authors wish to acknowledge the assistance of Mr. Micah Krichev- sky in identifying the sedoheptulose.

SUMMARY

1. Extracts of Pseudomonas jhorescens contain an intact system for the oxidation of G-l-P, G-6-P, F-6-P, 6-PG, R-5-P. F-l ,6-P was oxidized only slowly.

2. Glyceraldehyde-3-phosphate dehydrogenase was present in high con- centration. Phosphoglucomutase, phosphohexose isomerase, and aldolase activity could be detected, whereas phosphohexokinase could not.

3. DPN and TPN reduction by G-6-P was catalyzed by the particle fraction of sonic extracts.

4. DPNH was oxidized by molecular oxygen, whereas TPNH was not, except when DPN was added.

5. The soluble protein fraction catalyzed the reduction of DPN and TPN by 6-PG. In addition, 6-PG was converted to triose phosphate and py- ruvate at a 5- to IO-fold faster rate. Ribose-5-phosphate or ribulosed- phosphate was not involved in this process.

6. The anaerobic degradation of ribosed-phosphate or ribulose-5-phos- phate resulted in accumulation of sedoheptulose phosphate.

BIBLIOGRAPHY

1. Wood, W. A., and Schwerdt, R. F., J. Biol. Chem., 201, 501 (1953). 2. Stokes, F. N., and Campbell, J. J. R., Arch. Biochem. and Biophys., 30,121 (1951). 3. Koepsell, H. J., J. Biol. Chem., 186, 743 (1950). 4. Entner, N., and Starrier, R. Y., J. Bact., 62, 181 (1951). 5. Katznelson, H., and Tanenbaum, S. W., Federation Proc., 12, 470 (1953). 6. Klein, H. P., and Doudoroff, M., J. Bact., 69, 739 (1950). 7. Entner, N., and Doudoroff, M., J. Biol. Chem., 196, 853 (1952). 8. Wood, W. A., and Horecker, B. L., Biochem. Preparations, in press. 9. Ohlmeyer, P., Biochem. Z., 297, 66 (1938).

10. Lehninger, A., Biochem. Preparations, 2, 92 (1952). 11. Lardy, H., Biochem. Preparations, 1, 50 (1951). 12. Straub, F. B., Biochem. J., 34, 483 (1940). 13. Schmidt, G., and Thannhauser, S. J., J. Biol. Chem., 149, 369 (1943). 14. Horecker, B. L., and Smyrniotis, P. Z., J. Am. Chem. Sot., 75, 1009 (1953). 15. Mejbaum, W., 2. physiol. Chem., 268, 117 (1939). 16. Meyerhof, O., and Lohmann, K., Biochem. Z., 271,89 (1934). 17. Friedemann, T. E., and Haugen, G. E., J. Biol. Chem., 147,415 (1943). 18. Robinson, H. W., and Hogden, C. G., J. Biol. Chem., 136, 707 (1940). 19. Horecker, B. L., and Smyrniotis, P. Z., J. Am. Chem. Sot., 74, 2123 (1952). 20. Horecker, B. L., Smyrniotis, P. Z., and Klenow, H., Federation Proc., 12, 219

(1953). 21. Bevenue, A., and Williams, K. T., Arch. Biochem. and Biophys., 34, 225 (1951). 22. Benson, A. A., Bassham, J. A., Calvin, M., Goodale, T. C., Haas, Q. A., and

Stepke, W., J. Am. Chem. Sot., 72, 1710 (1950).

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. WOOD AND R. F. SCHWERDT 635

23. Colowick, S. P., Kaplan, N. O., Neufeld, E. F., and Ciotti, M. M., J. BioZ. Chem., 196, 95 (1952).

24. de la Haba, G., and Racker, E., Federation Proc., 11, 201 (1952). 25. Najjar, V. A., J. Biol. Chem., 1’76, 281 (1948). 26. Colowick, S. P., Cori, G. T., and Slein, M. W., J. Biol. Chem., 166, 583 (1947). 27. Sibley, J. A., and Lehninger, A. L., J. Biol. Chem., 177, 859 (1949). 28. Cori, G. T., Slein, M. W., and Cori, C. F., J. Biol. Chem., 173, 605 (1948).

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from

W. A. Wood and R. F. SchwerdtOXIDATION

MECHANISM OF HEXOSE PHOSPHATEPSEUDOMONAS FLUORESCENS: II. CARBOHYDRATE OXIDATION BY

1954, 206:625-635.J. Biol. Chem. 

  http://www.jbc.org/content/206/2/625.citation

Access the most updated version of this article at

 Alerts:

  When a correction for this article is posted• 

When this article is cited• 

alerts to choose from all of JBC's e-mailClick here

  tml#ref-list-1

http://www.jbc.org/content/206/2/625.citation.full.haccessed free atThis article cites 0 references, 0 of which can be

by guest on July 3, 2018http://w

ww

.jbc.org/D

ownloaded from