CHM 365 Chapter 5

What are examples of aldoses?

glucose, galactose, mannose, ribose

What are examples of ketoses?

ribulose and fructose (ketone at c2)

a/B configuration of glucose

OH and C6 are cis-B

trans-a

B configuration predominates due to less steric hindrance

Aldonic Acids

oxidation of aldehyde at C1 gives carboxylic acid

Uronic Acids

oxidation of 1º alcohol at C6, gives COOH

Alditols

Reduction of Aldehyde→ gives OH group

Amino Substitution

amine substitution of alcohol

NAc Group

nh-c=0-ch3

N Glycosidic Bonds

anomeric C attached to N

can undergo mutarotation

N-linked glycosylation

Asn-X-Ser/Thr

X- cannot be proline and is rarely Asp, Glu, Leu, or Trp

O-Glycosides

anomeric C to alcohol oxygen (condensation)

cannot undergo mutarotation (once bonded, locked into a/B configuration)

O-Glycosylation

no universal sequence motif

usually ends with Ser/THr

What are reducing sugars?

Lactose and Maltose

anomeric C with no glycosidic bond so it can reduce mild oxidizing agents

What is not a reducing sugar?

Sucrose

What are the functions of polysaccharides?

structural/protection (cellulose/chitin)

E storage (starch/glycogen)

What are examples of artificial sweetners?

acefulfame, alitame, aspartame, saccharin, sucralose

What are examples of sugar alcohols?

erythritol, xylitol, surbitol, maltitol

a-amylose

linear polymer of several thousand glucose residues by a(1→4) bonds

aggregates into helically coiled conformation

(gives easier access to glycosidic bonds)

Amylopectin

mainly a(1→4) bonds but has a(1→6) branch

branched molecule so it is more easily mobilized

Glycogen

Similar to amylopectin but it is more branched (quick immobilization of E)→can do glycolysis more rapidly

short-term E storage in animals

Cellulose

ruminants and termites produce cellulases

linear polymer of β (1→4) glucose residues that are not accessible to us

tightly packed and fully extended conformation

Chitin

Principal structural component of exoskeletons

NAc groups

Glycosamingoglycans

gel like matrix seen in connective tissue used for lubrication and cushioning

has charge-charge repulsion

Heparin

Glycosaminoglycan that is used to inhibit blood clotting

highly sulfonated

Proteoglycans

proteins+Glycosaminoglycan

highly negative charge that when compression removes H2O, charge-charge repulsion

Hyaluronate backbone

Glycoproteins

proteins with a carbohydrate modification

Peptidoglycan

has tetrapeptide crosslinker

forms pentaglycine bridges(Lys→Ala) and stabilizes peptidoglycan cell wall

Gram(+) - thick peptidoglycan cell wall on surface

Penicillin

inhibits crosslinking in peptidoglycans

Erythrocyte Glycocalyx

recognize by using lecins (proteins that bind to specific oligosaccharides)

can be used for affinity chromatography

Blood Antigens

H antigen is the precursor oligosaccharide to A and B antigens

O-both A/B antibodies

A- A antigen/B antibodies

B- B antigen/A antibodies

AB- A/B antigens, no antibodies