QC Biochem371 Chap 7 Vocab and question

ch.7 # 4 Describe the common structural features and the differences for each pair: (a) cellulose and glycogen; (b) D-glucose and D-fructose; (c) maltose and sucroseWhich bond(s) in a-glucose must be broken to change its configuration to B-D- glucose? --Which bond(s) to convert D -glucose to D-mannose? ---Which bond(s) to convert one "chair" form of D-Alucoseto the other?

-bond btw C-1 and hydroxyl on C-5 --either H or the OH on C-2 be broken ---does not require bond breakage,critical distinction btw configuration and confirmation

Hexose

6 carbon sugar

Proteoglycans

A glycoprotein in the extracellular matrix of animal cells, rich in carbohydrate

glycosidic bond

A glycosidic bond is a covalent bond in which a carbohydrate binds to another group, which could also be a carbohydrate. A glycosidic bond is found between the two glucose molecules in maltose. readily hydrolyzed by dilute acid, not base

cellulose

A substance (made of sugars) that is common in the cell walls of many organisms the linkage are Belta(1 to 4) and unbranched

Glycosaminoglycans

A water-binding substance between the fibers of the dermis.

23. Heparin Interactions Heparin, a highly negatively charged glycosaminoglycan, is used clinically as an anticoagulant. It acts by binding several plasma proteins, including antithrombin III, an inhibitor of blood clotting. The 1:1 binding of heparin to antithrombin III seems to cause a conformational change in the protein that greatly increases its ability to inhibit clotting. What amino acid residues of antithrombin III are likely to interact with heparin?

Answer Positively charged amino acid residues would be the best candidates to bind to the highly negatively charged groups on heparin. In fact, Lys residues of antithrombin III interact with heparin.

Anomers

Epimers that form as a result of ring closure

14. Gentiobiose Gentiobiose (D-Glc(1n6)D-Glc) is a disaccharide found in some plant glycosides. Draw the structure of gentobiose based on its abbreviated name. Is it a reducing sugar? Does it undergo mutarotation?

It is a reducing sugar; it undergoes mutarotation.

13. Anomers of Sucrose? Lactose exists in two anomeric forms, but no anomeric forms of sucrose have been reported. Why?

Lactose (Gal(b1n4)Glc) has a free anomeric carbon (on the glucose residue). In sucrose (Glc(a1mn2b)Fru), the anomeric carbons of both monosaccharide units are involved in the glycosidic bond, and the disaccharide has no free anomeric carbon to undergo mutarotation.

Mutarotation

The rapid interconversion between different anomers of a sugar

glycoside formation

a hemiacetal condenses with an alcohol

anomeric carbon

a stereocenter. An important feature is the direction of the OH group attached to the anomeric carbon. Depending on the direction of the OH group, the anomeric carbon is either α or β. α: equatorial DOWN or axial DOWN.

ch.7 # 6 Describe the common structural features and the differences for each pair: (a) cellulose and glycogen; (b) D-glucose and D-fructose; (c) maltose and sucrose

a) both are polymers of D-glucose, but they differ in the glycosidic linkage: beta (1---->4) for cellulose, (alpha 1-->4) for glycogen. b) both are hexoses, but glucose is an aldohexose, fructose a ketohexose. c) both are disaccharides, but maltose has two ( alpha 1--->4) linked D- glucose units; sucrose has (alpha 1 to 2 beta )-linked D- glucose and D-fructose

Hemiacetal Formation

an aldose or ketose condenses with an alcohol;

reducing sugar

any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. All monosaccharides are reducing sugars, along with some disaccharides, oligosaccharides, and polysaccharides.

Positively charged amino acid residues

best candidates to bind to the highly negatively charged groups

Amylopectin

branched starch

Amino acid

compound with an amino group on one end and a carboxyl group on the other end

absolute configuration

describes the exact spatial arrangement of groups of atoms independent of other molecules.

sucrose

disaccharides has (alpha 1 to 2 beta )-linked D- glucose and D-fructose

maltose

disaccharides has two ( alpha 1--->4) linked D- glucose units;

sucrose

glucose + fructose the anomeric carbons of both monosaccharide units are involved in the glycosidic bond, and the disaccharide has no free anomeric carbon to undergo mutarotation.

Lactose

glucose + galactose has a free anomeric carbon (on the glucose residue).

8.Hemiacetal and Glycosidic Linkages Explain the difference between a hemiacetal and a glycoside

hemiacetal is formed when an aldose or ketose condenses with an alcohol; a glyco-side is formed when a hemiacetal condenses with an alcohol (see Fig. 7-5, p. 238)

D-glucose

hexoses aldohexose

D-fructose

hexoses ketohexose

glycogen

polymers of D-glucose, (alpha 1-->4) glycosidic linkage

cellulose

polymers of D-glucose, beta (1---->4) glycosidic linkage

Amylose

simplest form of starch