40. Galactose, Fructose, Sorbitol, Uronic acid Pathway Flashcards
phosphorylation of galactose
enzyme
galactokinase
formation of UDP galactose
Galactose-1-P + UDP-glucose -> UDP galactose + glucose-1-P
enz: galactose-1-P uridyl transferase (GALT)
use of galactose as carbon source
UDP-galactose -> UDP- glucose
enz: UPD-hexose-4-epimerase
- this has mild symptoms
- galactosemia and galactosuria
- cataracts in early childhood
galactokinase deficiency
- more severe symptoms
- galactosemia, galactosuria, diarhea. vomiting, jaundice,
- poor growth
- severe mental retardation
- liver damage
- premature ovarian failure in females
classic galactosemia /
galactose-1-phosphate-uridyl transferase deficiency
phosphorylation of fructose
fructokinase/ hexokinase
formation of DHAP + glyceraldehyde
Fructose-1-P -> DHAP + Glyceraldehyde
Enz: Aldolase B
symptoms of fructokinase deficiency/ essential fructosuria
benign
asymptomatic
Hereditary fructose intolerance is deficient of what enzyme
aldolase B
s and sx of
Hereditary fructose intolerance
- profound hypoglycemia and vomiting after consumption of fructose or sucrose
- jaundice
- hemorrhage
- hepatomegaly
- renal dysfunction
- hyperuricemia
- lactic acidosis
- death
- appear after weaning from milk
tx of Hereditary fructose intolerance
eloiminate fructose, sucrose and sorbitol from diet
conversion of glucose to sorbitol requires what enzyme
aldose reductase
aldose reductase are found in
lens, retina schwann cells liver kidney placenta rbc ovaries seminal vesicles
Conversion of sorbitol to fructose
sorbitol dehydrogenase
sorbitol dehydrogenase is found in
liver
ovaries
seminal vesicles
flatulence and diarrhea after ingestion of dairy products
seen in 90% of african or asian descent
lactose intolerance
lactase deficiency
tx of lactose intolerance
reduce consumption of milk
use of lactase treated products and or lactase pills
- intolerance of ingested sucrose
* see in 10% f unuit people in greenland/ canada
sucrase-isomaltase complex deficiency
alternative pathway for oxidation of glucose in the liver
uronic acid pathway
main pathway for production of glucuronic and iduronic acid
uronic acid pathway
this pathway synthesized ascorbic acid in plants and mammals
uronic acid pathway
this enzyme is not present in guinea pigs and primates , hence they cannot produce vit C
L-gulonolactone oxidase
required for detoxification of bilirubin, steroids, morphine
-component of GAGs
glucuronic acid
essential pentosuria is deficient of this enzyme
xylulose reductase
inc xylulose in urine
essential pentosuria
xylulose reductase deficiency
