URONIC ACID PATHWAY

CONTENTS

DEFINITION OCCURRENCE & TISSUE

DISTRIBUTION BIOMEDICAL IMPORTANCE METABOLIC STEPS REGULATION CLINICAL IMPORTANCE REFERENCES ACKNOWLEDGEMENTS

DEFINITION

IT IS AN ALTERNATIVE PATHWAY FOR

OXIDATION OF GLUCOSE.

OCCURENCE

IN CYTOPLASM

TISSUE DISTRIBUTION

LIVERADIPOSE TISSUE

BIOMEDICAL IMPORTANCE

Major Function is to produce D-Glucuronic acid which is required for:

Detoxification of foreign chemicals.

Synthesis of MPS.There is no energy production.

METABOLIC STEPS

GLUCOSE Glucokinase ATP ADP

Glucose 6-

phospatePhosphogluco-Mutase Glucose 1-

phosphate

CONTINUED:

UDP-Glu-pyrophos- UTP PPi

Phorylase UDP-GlucoseUDP-Glu- 2NAD+ 2NADH

+ H+ dehydrogenase UDP-Glucoronate

phosphorylation D-Glucuronic acid 1-P

CONTINUED:

Glucuronidase H2O UDP

D-Glucoronic acid LGDH L-Gulonic acid

CONTINUED:

L-Gulonic acid beta-HD L-

Gulonolactone

oxidase3-Ketogulonic L-

Ascorbic acidAcid beta-keto L-gulonate

decarboxylase L-Xylulose

CONTINUED:

Xylulose reductase Xylitol NAD+

NADH + H+

D-Xylulose Xylulose kinase ATP ADP Xylulose 5-phosphate

HMP Shunt

REGULATION

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.

CLINICAL IMPORTANCE

o ESSENTIAL PENTOSURIA: It is an Autosomal recessive

disorder.

Metabolic defect:-

Deficiency of Xylitol Reductase

REFERENCES

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