Biochemistry-Ch 11. Carbohydrates (Cont.)

阮雪芬NTUT

Nov 18, 2002

ABO Blood Groups

Glycosidic Bonds Between Proteins and Carbohydrates

N-linked Oligosaccharides

N-linked Oligosaccharides

Elastase

Protein Glycosylation Takes Place in the Lumen of the Endoplasmic Retic

ulum and in th Goligi Complex

Transport Into The Endoplasmic Reticulum

Golgi Complex as Sorting Center

Formation of a Mannose 6-phosphate Marker

I-cell Disease: deficient in the phosphotransferase.

Quality-control System for The Protein Folding in the ER

Mass Spectrometric “sequencing” of Oligosaccharides

Peptide N-glycosidase F

Peptide N-glycosidase F, neuraminidase F and -1, 4-galatosidase

Binding Selectivities of Plant Lectins

Lectins are ubiquitous, being found in animals, plants, and microorganisms.

The chief of lectins in animals is to facilitate cell-cell contact.

C-type in Animals

A calcium ion acts as a bridge between the protein and sugar through direct interactions with sugar hydroxyl groups.

Selectins Mediate Cell-cell Interactions

L: lymph-node vessels

E: endothelium P: activated

blood platelets

Structure of A Part of Influenza Hemagglutinin

Influenza virus recognizes sialic acid residues present on cell-surface glycoproteins. The viral protein that binds to these sugars is called hemagglutinin.

Neuraminidase

Another viral protein, neuraminidase, cleaves the glycosidic bonds to the sialic acid residues, freeing the virus to infect the cell.

Inhibitor of this enzyme are showing some promise as anti-influenza agents.