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PathWhiz ID Pathway Meta Data

PW391071

Pw391071 View Pathway
metabolic

Ascorbate Metabolism

Escherichia coli SE15
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW391230

Pw391230 View Pathway
metabolic

Ascorbate Metabolism

Achromobacter xylosoxidans A8
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW394284

Pw394284 View Pathway
metabolic

Ascorbate Metabolism

Helicobacter cinaedi CCUG 18818 = ATCC BAA-847
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW394323

Pw394323 View Pathway
metabolic

Ascorbate Metabolism

Citrobacter amalonaticus Y19
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW392891

Pw392891 View Pathway
metabolic

Ascorbate Metabolism

Bacteroides cellulosilyticus DSM 14838
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW394405

Pw394405 View Pathway
metabolic

Ascorbate Metabolism

Edwardsiella tarda ATCC 23685
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW394607

Pw394607 View Pathway
metabolic

Ascorbate Metabolism

Paenibacillus lactis 154
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW396343

Pw396343 View Pathway
metabolic

Ascorbate Metabolism

Escherichia coli O55:H7 str. CB9615
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW390770

Pw390770 View Pathway
metabolic

Ascorbate Metabolism

Escherichia coli (strain ATCC 8739 / DSM 1576 / Crooks)
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.

PW684480

Pw684480 View Pathway
metabolic

Ascorbate Metabolism

Porphyromonas uenonis 60-3
E. coli is able to utilize L-ascorbate (vitamin C) as the sole source of carbon under anaerobic and aerobic conditions. Ascorbic acid in the cytoplasm is processed through a spontaneous reaction with a hydrogen ion and hydrogen peroxide, producing water, dehydroascorbic acid and ascorbic acid. Dehydroascorbic acid reacts with water spontaneously producing an isomer, dehydroascorbate (bicyclic form). The compound then loses a hydrogen ion resulting in a 2,3-Diketo-L-gulonate which is then reduced through a NADH dependent 2,3 diketo-L-gulonate reductase, releasing a NAD and 3-Dehydro-L-gulonate. 3-Dehydro-L-gulonate is phosphorylated through an ATP mediated L-xylulose/3-keto-L-gulonate kinase resulting in an ADP, hydrogen ion and a 3-Keto-L-gulonate 6 phosphate. L-ascorbate can also be imported and converted to L-ascorbate-6-phosphate by the L-ascorbate PTS transporter. L-ascorbate-6-phosphate reacts with a probable L-ascorbate-6-phosphate lactonase ulaG, resulting in a 3-keto-L-gulonate 6-phosphate. The compound 3-keto-L-gulonate 6-phosphate can then be processed aerobically or anaerobically. Aerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by a 3-keto-L-gulonate-6-phosphate decarboxylase ulaD, releasing carbon dioxide and L-xylulose-5-phosphate, which is then changed into an isomer by L-ribulose-5-phosphate 3-epimerase ulaE, resulting in L-ribulose 5-phosphate. The product also changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase ulaF resulting in Xylulose 5-phosphate, which is finally used as part of the pentose phosphate pathway. Anaerobic: 3-keto-L-gulonate 6-phosphate is decarboxylated by 3-keto-L-gulonate 6-phosphate decarboxylase sgbH, releasing carbon dioxide and L-xylulose-5-phosphate, which is changed into an isomer by predicted L-xylulose 5-phosphate 3-epimerase, resulting in L-ribulose 5-phosphate. The product again changes into a different isomer through a L-ribulose-5-phosphate 4-epimerase resulting in Xylulose 5-phosphate. Xylulose 5-phosphate then continues as part of the pentose phosphate pathway. Expression of the ula regulon is regulated by the L-ascorbate 6-phosphate-binding repressor UlaR and by cAMP-CRP. Under aerobic conditions, metabolism of L-ascorbate is hindered by the special reactivity and toxicity of this compound in the presence of oxygen.