This document summarizes the uronic acid pathway, an alternative pathway for glucose oxidation that occurs in the cytoplasm of liver and adipose tissue. The major function of this pathway is to produce D-glucuronic acid, which is required for detoxification of foreign chemicals and synthesis of mucopolysaccharides. The pathway proceeds through a series of enzymatic steps beginning with glucose and ultimately producing D-glucuronic acid. Regulation of the pathway involves administration of certain drugs that increase production of uronic acid and ascorbic acid. Clinical importance includes essential pentosuria, an inborn error of metabolism caused by deficiency of the enzyme xylitol reductase.

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DEFINITION
OCCURRENCE & TISSUE
DISTRIBUTION
BIOMEDICAL IMPORTANCE
METABOLIC STEPS
REGULATION
CLINICAL IMPORTANCE
REFERENCES
ACKNOWLEDGEMENTS

4. IT IS AN ALTERNATIVE
PATHWAY FOR
OXIDATION OF
GLUCOSE.

5. IN CYTOPLASM

6. LIVER
ADIPOSE TISSUE

7. Major Function is to produce
D-Glucuronic acid which is required
for:
Detoxification of foreign chemicals.
Synthesis of MPS.
There is no energy production.

8. GLUCOSE
Glucokinase ATP ADP
Glucose 6-phospate
PhosphoglucoMutase
Glucose 1-phosphate

9. UDP-Glu-pyrophosPhorylase
UTP PPi
UDP-Glucose
UDP-Gludehydrogenase
2NAD+ 2NADH + H+
UDP-Glucoronate
phosphorylation
D-Glucuronic acid 1-P

10. Glucuronidase
H2O UDP
D-Glucoronic acid
LGDH
L-Gulonic acid

11. L-Gulonic acid
beta-HD
L- Gulonolactone
3-Ketogulonic
Acid
oxidase
L-Ascorbic acid
beta-keto L-gulonate decarboxylase
L-Xylulose

12. Xylulose reductase
Xylitol
NAD+ NADH + H+
D-Xylulose
Xylulose kinase
ATP ADP
Xylulose 5-phosphate
HMP Shunt

13.  Administration of drugs i.e
Chlorobutanol &
Barbital significantly increases the uronic
acid pathway.
 Certain drugs are also found to enhance
the synthesis of Ascorbic acid.

14. o ESSENTIAL PENTOSURIA:
It is an Autosomal recessive disorder.
Metabolic defect:Deficiency of
Xylitol Reductase

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BIOCHEMISTRY BY THOMAS. M.DEVLIN
,Edition no.7Pg.655 &656
HARPER’S ILLUSTRATED BIOCHEMISTRY
EDITION NO.29,Pg.201 &202
MED. BIOCHEMISTRY BY MN.CHATTERJEA
EDITION NO.8, Pg.362 & 363
BIOCHEMISTRY BY U.SATYANARAYANA
EDITION NO.3, Pg.276