Wk1 Carbohydrates Flashcards
Endoglycosidase
cuts a-1,4 bonds
highest activity in duodenum
Amylase
4 disaccharidases of the brush border:
- Glucoamylase
- Sucrase / Isomaltase complex
- Trehalase
- B-glycosidase complex
Exoglycosidase
cleaves a-1,4 bonds of MALTOSE
cuts glucose of non-reducing end of starch
highest activity in ileum
Glycoamylase / maltase
two substrate specific domains
cuts sucrose into glucose and fructose
cuts the a-1,6 bond in isomaltase
highest activity in jejunum
Sucrase / isomaltase complex
glycosyl ceramide domain
lactase domain
highest activity in jejunum
B-glycosidase complex
How is the B-glycosidase complex anchored to the brush border membrane?
glycophosphotidyinositol (GPI) glycan anchor
Substrate for lactase domain of B-glycosidase complex:
1.4 bond of lactose —> galactose + glucose
What happens in lactase deficiency?
bacteria ferment lactose to lactic acid
water enters lumen to balance proton difference –> diarrhea
Two monosaccharides forming lactose:
galactose
glucose
two monosaccharides forming sucrose:
glucose
fructose
glucose polysaccharide with a-1,4 bonds:
amylose
glucose polysaccharide with a-1,4 bonds and a-1,6 branches:
amylopectin
Glu + Glu with a-1,1 bond:
Trehalose
a-1,4 bonds (in the chain, not on the ends)
enzyme?
location?
amylase
duodenum
a-1,4 bonds (maltose –> 2 glucose)
enzyme?
location?
maltase (glucoamylase/maltase)
ileum
