Biochem Exam 4

Carbohydrate composition

C, H, O

Monosccharides composition

Aldehyde or ketone, 3+ carbons, polyhydroxy alcohols

How many monosaccharides are in a polysaccharide?

3 or more

What do polysaccharides do?

store energy

how to name monosaccharides

-functional group
-carbon number
-stereochemistry of last chiral carbon

Aldehyde functional group and suffix

aldose

Ketone functional group and suffix

ketose

3 carbon monosaccharide

triose

4 carbon monosaccharide

tetrose

D

-OH on the right
-OH in the up position

L

-OH on the left
-OH in the down postion

Epimers

differ at exactly one chiral carbon

can there be more than one epimer for a sugar?

yes

how are cyclic sugars made?

By the alcohol on the last carbon chiral carbon reacting with the carbonyl group

6 member ring

pyranose

5 Member Ring is called

furanose

how do you number the rings?

clockwise from the anomeric carbon

alpha

OH down
-opposite of D/L carbon

Beta

OH is up
-same side and of D/L carbon

are both alpha and beta present in a solution?

yes they are 50/50 in solution because they spontaneously convert between both

Mutarotation

switching between D and L

Oxidation of sugars at C1

-becomes carboxylic acid
-only aldehyde
aldose becomes aldonic acid

Oxidation of sugars at last carbon

-also changes to carboxylic acid
-more soluble
-primary alcohol = uronic acid

Reduction of sugars

aldose or ketose = alditols
-loose solubility

replace OH groups in sugars with H+

-Deoxy
-changes the size of molecule smaller
-protonates

replace OH groups with NH2

-Amino sugar
-changes the size of molecule bigger
-protonates

glycosidic bond

Anomeric carbon condenses with alcohol
-alpha
-beta

How to name glycosidic bonds?

Greek letter ( C# mononsaccharide 1 - C# monosaccharide 2)

What is a reducing sugar?

free anomeric carbon

What is a non-reducing sugar?

no free anomeric carbon

Polysaccharides/ glycans

monosaccharides linked by glycosidic bonds

Homopolysaccharides

same monosaccharides

Heteropolysaccharides

different monosaccharides

Oligosaccharides

short chains of three or more monosaccharides

exoglycosidases

cuts terminal sugar at glycosidic bond

Endoglycosidases

cleaves middle of sugar chain at glycosidic bond

Disaccharide

2 monosaccharides

Cellulose

-plant cell walls
-beta(1-4) glucose
-reducing sugar

Why does cellulose form sheets?

partners are 180 degrees from each other, allowing them to pack closely together

why cellulose water insoluble?

Occupies all of the H+ with the sheets instead of H2O
-no room

Chitin

beta(1-4) N-acetyl-D-Glucosamine *add amine group to carbon 2
-makes the molecule bigger
-that changes H+ bonding making it slightly less hydrophobic

Starch structure

amylose and amylopectin
-reducing sugar
-reduces osmotic pressure

Structure of amylose

alpha(1-4) glucose
-helical

structure of amylopectin

alpha(1-4) glucose with alpha (1-6) branched

Digestion of starch

amylase, alpha-glucosidase, and debranching enzyme

What does amylase do?

-found in the small intestine and saliva
-randomly hydrolyzes alpha(1-4)

what does Alpha-glucosidase do?

-removes 1 glucose at a time

What does the debranching enzyme do?

hydrolyzes alpha(1-6) linkages
-gets rid of the branches

where is glycogen found?

animals

what is the structure of glycogen?

resembles amylopectin but with more branching
-a branch every 8-12 glucoses

what is glycogen digested?

glycogen phosphorylase and glycogen debranching

How does glycogen phosphorylase work?

breaks the Alpha(1-4) from the nonreducing ends

how does glycogen debranching enzyme work?

breaks the alpha(1-6) bond

Glycosaminoglycans structure

alternating uronic and hexoamine residue
-unbranched

Example of a glycosaminoglycan

hyaluronic acid, heparin

Can glycosaminoglycan be phosphorylated?

yes

Pectin structure

heterogeneous polysaccharides
- alpha(1-4) galacturonate with rhamnose

What do pectins do?

take liquid and make it solid in plants
-Requires Ca+

Proteoglycan structure inside-out

-Hyaluronate
-core protein
-N-linked oligosaccharides
-Keratan sulfate
-chondroitin sulfate
*all covelantly linked

what is an example of a glycoprotein?

Proteoglycan

Proteoglycan definition

covalent and noncovalent aggregations of proteins and glycosaminoglycans in the extracellular matrix
(sugar protein outside of the cell)

Proteoglycan characteristics

-Huge
-polyanionic characteristics (charge-charge interaction)
-highly hydrated gels

what are hydrated gels?

absorb water and coushin

peptidoglycan

-makes up cell wall of bacteria
-thickness and complexity of cell wall determines gram - or +

peptidoglycan structure

Polymer of disaccharide.
NAG: N-acetylglycosamine (shorter, OH-H),
NAM: N-acetylmuramic acid (longer, H/O-HC-CH3-C=O-OH). Linked by Polypeptide Cross Bridge (pentaglycine)

glycosylated

proteins with oligosaccharide covalantly attached

how are the the oligosaccharides attached to proteins?

N linked then Asn-X-Ser or Thr
*X can be any amino acid except Pro and rarely Asp
-then it is chopped until there is only 3 mannoses making the Y
-other molecules can be added to the mannoses after the chopping

what makes up the base Y for all N-linked oligosaccharides?

3 mannones and 2 GlcNAc

O-linked oligosaccharides

*have glycosidic bond to the hydroxyl group of Ser or Thr residues
*synthesized in the Golgi
*more common
*condensation Rxn

glycoforms

same protein with variation in sequence, location, and number of covalently attached carbohydrates

function of glycoforms

1) define protein structures
2) mediated recognition events
3) antigenic Determinants

Lipid definition

non-polar organic molecule

fatty acid definition

carboxylic acid with a long chain hydrocarbon side group (tail)

saturated fatty acid

-only single bonds
-tightly packed
-melting point increases

unsaturated fatty acid

-contains double bonds
-rigid, cis configuration
-lose packing
-reduced interactions
-lower melting points

how do you know which carbon has a double bond?

Delta symbol C# that starts the double bond

Triacylglycerols (triglycerides) structure

-2-3 different types of fatty acids
-bound by an ester linkage

Triacylglycerol functions

-energy storage in animals
-provide warmth

Why do triacylglycerols make such a good form of energy storage?

they are less oxidized than carbohydrates

How to name triacylglycerols?

by adding -oyl to the end of each fatty acid and ending with glycerol

How do we end up with trans fat?

-to preserve shelf life and avoid oxidation of unsaturated fats, the unsaturated fats are hydrogenated to reduce some double bounds
-this converts the cis bonds to trans

why do transfats cause cardiovascular disease?

Because our digestive enzymes can't break down the trans bond leaving these big hunks of fat in out blood stream to get stuck and narrow arteries

what configuration do unsaturated fatty acids take?

Cis

which configuration would have a high melting point?

trans because it can pack closer together

Phosphoglycerides

C1 and C2 esterfied with fatty acids
C3 contains phosphate
-amphiphilic

amphiphilic

non polar aliphatic tails and polar phosphoryl-X heads

phosphatidic acid structure

-X is H+
-C1 is saturated with 16 - 18 carbons
-C2 is unsaturated with 16-20 carbons

Phospholipase

-enzyme that Hydrolyzes glycerophoslips
*changes structure and disrupts membranes
-insoluable

why would antibodies recognize both phospholipids and DNA

both have exposed phosphate groups

plasmolagens

Contains an ether linkage instead of ester linkage

Sphingolipids

-long fatty acid chain
-polar head group
backbone=amino alcohol (not glycerol)
*only attach at positions 1 and 2

example of sphingolipid

Sphingomyelin, ceramide

ceramide

N-acyl fatty acid derivative of sphingosine

Sphingosine

A complex alcohol backbone for membrane lipids with an 18 C side chain

Sphingomyelin

Bear phosphocholine or phosphoethanolamine group

Cerebrosides

ceramide + monosaccharide
*mediates recognition events

gangliosides

ceramide linked to an oligosaccharide

steroid structure

4 fused, nonpolar rings

types of steroid hormones

Glucocorticoids
Mineralocorticoids
Androgens
Estrogens

Glucocorticoids

affect carbohydrate, protein and lipid metabolism