Glycosidases

Glycoside Hydrolysis

Enzymes that turnin an aldonic acid into an aldose

Glycosidases

• Sugar-C1-O-R -(Glycosidases)-> Sugar & R-OH

Function/Purpose:

• Hydrolyze glycosides

Mechanism:

Fundamentals:

• Cyclic form cannot open to the free carbonyl
• Acetals are stable under neutral and basic conditions
  • Cyclic acetals cannot open to the free carbonyl compound
• Glycosides cannot spontaneously opne to their open chain forms
• Glycosides do not mutarotate and are locked in anomeric form
• Glycosides are stable in basic conditions
• Glycosides hydrolyze in aq acid to reform sugar and R-OH

Structure of Glycoside:

• Sugar
• Glycosidic bond
• Aglycone

Salient Examples:

Concepts:

• Enzymes
• Carbohydrates

Terminology:

• Glycoside: sugars that are full acetal stable to Tollens reagent
  • Nomenclature - root 'oside'
• Nonreducing sugars: unreactive to Tollens reagent
• Aglycone: non-sugar residue on the C1 anomeric carbon

Additional Information: