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MedChem Midterm 3 > Carbohydrates 2 > Flashcards

Carbohydrates 2 Flashcards

1
Q

Polysaccharide Properties

A
  • polymers (mW>200k
  • NOT SWEET
  • most are NOT reducing
    • do not test positive on aldose/ketose detection rxns
    • ex. fehling’s test
  • ​not water soluble
    • –> form colloidal solutions/suspensions
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2
Q

Homopolymer

A

Polysaccharide w/ only 1 type of monomer

  • Cellulose
  • Amylose
  • Chitin
  • Amylopectin
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3
Q

Heteropolymer

A

Polysaccharide composed of more than 1 kind of monomer

  • Chondroitin
  • Peptidoglycan
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4
Q

Cellulose

A
  • Most abundant of all carbohydrates
  • polymer of D-glucose attached by beta1-4 linkages
    • hydrolysis –> glucose
    • partial hydrolysis –> cellobiose
  • Only digested and utilized by Ruminants (cows/deers/horses)
  • Held together w/ LIGNIN
    • in woody plant tissues
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5
Q

Cellulose

Glycosidic Bond Conformation

A
  • Cellulose is made of Beta 1-4 repeats
    • Both dihedral angles are small and of opposite direction
      • –> gives cellulose a linear chain conformation​​
        *
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6
Q

What determines the overall 3d structure of polysaccharides?

A

Rotation about the C1-O & O-C4 bonds =

dihydral angles (phi&psi)

aka torsion angles

*ramachandran plot

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7
Q

Cellulose

Interchain Hydrogen Bonds

A
  • Neighboring chains interact via:
    • Intramolecular hydrogen bonds
    • ​​6-OH to 6-O
    • 5-O to 3-OH
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8
Q

Why is cellulose resistant to most glycosidases?

A

Very tight packing of chains

h-bonds between neighboring chains

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9
Q

Can mammals digest cellulose?

A

NO

  • ruminants feed on cellulose because their gut contains bacteria
    • ​CELLULASE in the bacteria that can break cellulose down
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10
Q

Products from Cellulose

Microcrystalline cellulose

A

Used as a binder-disintegrant in tablets

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11
Q

Products from Cellulose

Methylcellulose

A

Suspending Agent

Bulk Laxative (Citrucel / GSK)

NONSTIMULANT

hair shampoos / tooth paste / liquid soaps

  • EMULSIFYER
    • added to foods to prevent seperation of liquid phases (ice cream
  • NOT DIGESTED, passes through GI
    • –> laxative / stool softener
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12
Q

Products from Cellulose

Sodium Carboxylmethyl Cellulose

A

Lubricant in tear drops

Laxative

Toothpaste

Thickening Agent

Component of laundry detergents

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13
Q

Products from Cellulose

Cellulose Acetate

A

Rayon

Photographic Film

Plastics

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14
Q

Products From Cellulose

Cellulose Acetate PTHALATE

A

Enteric Coating –> to be released in small intestine

*stable @ low pH

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15
Q

Products From Cellulose

Nitrocellulose

A

Explosives

Collodion (pyroxylin)

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16
Q

Starch

Amylose & Amylopectin

A
  • Most Common storage polysaccharide in plants
  • Alpha-1>4 linked D-glucose units
  • 10-30% a-amylose
  • 70-90% amylopectin
    • ​highly branched structure
    • chains of varying lenghth
      • can have MW from thousands to half a million
  • Broken down by AMYLASE
  • left handed alpha helix
17
Q

Starch Uses

A

Storage / Fuel

Excipient

Adhesives / Paper Manufacturing

  • sourced from rice/corn/wheat/potatoes
18
Q

Starch Detection

A
  • Suspensions of amylose in water –> HELICAL CONFORMATION
    • ​​​Iodine (I2) –> in middle of amylose helix
      • –> BLUE COLOR
19
Q

Glycogen

A

ANIMAL “STARCH”

  • both a(1,2) links & a(1,6 branches) @ every 8-12 glucose unit
    • more frequent than starch
    • complete hydrolysis –> glucose
  • mostly stored in muscle / liver
  • High MW, present in cells as granules
    • Circular / spherical shape
      • FINITE size
  • Glycogen + Iodine = Red-Violet color
20
Q

How is Glycogen Hydrolyzed?

A

Both Alpha & Beta Amylases

and by glycogen phosphorylase

  • A-amylase
    • exo-glysidase, breaks chain at ANY position
    • found in saliva
      • why starchy items are sweet
      • break starch –> glucose
  • B-amylase
    • ENDO-glycosidase
      • starts at NONREDUCING END
    • less efficient
21
Q

Chitin

A
  • SECOND most abundant carbohydrate poymer
  • LINEAR B(1,4)- linked polymer of N-acetylglucosamine
  • ​Alike cellulose = structural polymer
  • Cell wall of fungi
  • Exoskeletons of crustaceans insects spiders
  • Coatings
    • extends shelf life of fruits / meats
      • binds to iron in meat –> slow rancidity
        • degradation of unsatFATS by oxygen
    • strong linear biodegradable polymer
    • surgical thread​
22
Q

Glycosaminoglycans

A

Polysaccharide chains of Proteoglycans

  • Linked to protein core via Serine or Threonine
    • O-linked
  • LINEAR chains, very long >100 monosaccharides
    • repeating disaccharides
    • ACIDIC FUNCTIONALITIES
      • ​carboxylate or sulfates
      • dense negative charge
  • More Glycan than Protein​
23
Q

Glycosaminoglycans

Hyaluronan

A
  • 50,000 repeats
    • largest amount of repeats, LARGE MW
    • LINEAR
  • B1>3 link between units
24
Q

​Glycosaminoglycans

Keratan Sulfate

A
  • ~25 repeats
  • Negative Charge (similar to chondroitan sulfate
    • But LINKED DIFFERENTLY
    • B1>4
  • ​
25
Q

​Glycosaminoglycans

Chondroitin Sulfate

A
  • Same links as hyaluronan
    • ​B1>3
  • Some glucose groups are SULFONATED
    • ​–> MORE ACIDIC
    • higher density of acidic charge
26
Q

​Glycosaminoglycans

Heparin

A
  • 15-90 repeats
  • Hydroxyl group is points UP OR DOWN
    • Changes in configuration of L/D
  • ​​​A1->4 repeating (not linear)
  • More sulfate groups attached
    • ​more negative charge
    • density varies along chain
  • Areas w/ more sulfates = pentasaccharides
27
Q

Hyaluronic Acid

A
  • NONSULFATED
  • Very large MW B1>3 linked COpolymer
    • COpolymer = alternating repeats
      • Glucuronic Acid
      • N-acetyl glucosamine
  • ​Viscous & Absorbs Water
    • ​used as a LUBRICANT
  • ​Forms protective viscoelastic coating @ inner surface of JOINT (SYNOVIUM) / Cartilage
    • _​_also shields local pain receptors​
  • ​Many Negative Charges
    • ​occupy volume 100x that of its dry state
28
Q

Assembly of Hyaluronic Acid

A

Keratan Sulfate + Chondroitin Sulfate

attached to Hyaluronate

  • One of the most Hydroscopic molecules in nature
    • 500-1k times its weight in water
    • >1% solution = very THICK
  • Chain is attached NONcovalently to aggrecan adapter protein
    • ​protein has multiple chains of keratan/chondroitan sulfate
      • they are attached covalently to serines & threonines of aggrecan
    • 100,000 dimers long
29
Q

Viscoelastic Properties

of HA

A

Ability to take SHOCK & Lubricate

  • Think of this in a Joint
    • over time HA becomes LESS shock absorbing
    • because it stretches out and UNTANGLES
      • chain length REDUCED WITH AGE
  • During Strong/Fast impact
    • HA serves as a cushion
      • exhibit elastic properties
  • ​​During SLOW gradual SHEER stress of longer duration
    • ​the polymer chain stretches / align
      • –> exhibit Viscous properties as a lubricant
30
Q

Why is the hydrated volume of HA so much GREATER?

A
  • Polymer chain in Chondroitin Sulfate
    • ​contain a large # of negative charges
      • repel each other via COULOMBIC interactions
  • ​​Coulombic interactions
    • ​are RELIEVED when polysacchride strains are seperated by solvating water
      • –> Increase the Molecular volume
  • ​​Process is efficient due to:
    • High dielectric constant of aqueous medium​
31
Q

HA Pharmaceuticals

Hyalgan / Synvisc

A

Used in management of

Osteoarthritis Symptoms

Injections of HA –> Plastic Surgry / Facial augmentation

COSMETICS

32
Q

HA Pharmaceuticals

Healon / Amvisc / AMO Vitrax

A

Eye drops / Opthalmic Surgical Adjuct

Cataract Extractions

Intraocular Lens Impantion

Corneal Transplant

Retinal Attachment Surgery

33
Q

Heparin

A
  • Acidic Carb w/ ANTICOAGULANT properties
    • ​Prevent blood clots in patients recovering from injury/surgery
  • Dimers of
    • Sulfated Glucosamine
    • Sulfated Glucuronic Acid (iduronic)
      • some areas w/ more sulfate = S-domains
        • more negatively charged
  • Long natural chain with HIGH MW
    • but synthetically made to be short for therapeutics
34
Q

Heparin
MOA

A

–> FACTOR 10A (Xa)

Intervenes with the Blood Coagulation Cascade

@ INITIATION PHASE

  • Factor Xa is a serene protease that catalizes breakdown of peptide.
    • Prothrombin + Xa –> THROMBIN
      • thrombin cuts fibrinogen –> fibrin
      • = causes cross linked CLOT
35
Q

Fondaparinux

A

Synthetic PentaSaccharide

Simular to Heparin

Pulmonary Embolism

DVT

36
Q

Carrageenan

A

Sulfated B1>4 linked Galactan

  • Derived from red algae (seaweed)
  • For Foods:
    • Thickener / Stabilizer / Emulsifyer
    • gives food a SMOOTH texture
      • –> dairy products / jely / pie filling / chocolate / pet food
  • Also Toothpaste, cosmetics, fire fighting foam, shoe wax
    • ​Large commodity –> 100k produced per year
  • Suspected to cause –> Gastric ulcers / cancer
    • In research for causing SC Inflammation in annimals
  • insoluble in water –> colloidal dispersions
  • Linear & biodegradable polymer, used in surgical threads
37
Q

Levoglucosan

A

Carrageenan + Alkali –> Levoglucosan (ANHYDRO-SURGAR)

  • A monomeric anhydrosugar
  • Formed after processing Carrageenan with Alkali
    • BASIC CONDITIONS –> form the levoglucosan

MedChem Midterm 3 (7 decks)

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