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MedChem Midterm 3 > Carbohydrates 2 > Flashcards

Carbohydrates 2 Flashcards

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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

Study These Flashcards
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

Study These Flashcards
A

Storage / Fuel

Excipient

Adhesives / Paper Manufacturing

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

Starch Detection

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

Glycogen

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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?

Study These Flashcards
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

Study These Flashcards
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

Study These Flashcards
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

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

​Glycosaminoglycans

Keratan Sulfate

Study These Flashcards
A
  • ~25 repeats
  • Negative Charge (similar to chondroitan sulfate
    • But LINKED DIFFERENTLY
    • B1>4
  • ​
25
​Glycosaminoglycans ## Footnote **Chondroitin Sulfate**
* Same links as **hyaluronan** * **​B1\>3** * Some glucose groups are **SULFONATED** * **​--\> MORE ACIDIC** * higher density of acidic charge
26
​Glycosaminoglycans ## Footnote **Heparin**
* 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
**Hyaluronic Acid**
* **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
**Assembly of Hyaluronic Acid**
**Keratan Sulfate + Chondroitin Sulfate** attached to **Hyaluronate** * One of the most **Hydroscopic molecule**s 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
**Viscoelastic Properties** of **HA**
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
Why is the hydrated volume of HA so much GREATER?
* 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
HA Pharmaceuticals **Hyalgan / Synvisc**
Used in management of **Osteoarthritis Symptoms** **Injections of HA --\> Plastic Surgry / Facial augmentation** **COSMETICS**
32
HA Pharmaceuticals ## Footnote **Healon / Amvisc / AMO Vitrax**
Eye drops / Opthalmic Surgical Adjuct ## Footnote **Cataract Extractions** **Intraocular Lens Impantion** **Corneal Transplant** **Retinal Attachment Surgery**
33
**Heparin**
* **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
**Heparin MOA**
**--\> 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
**Fondaparinux**
Synthetic PentaSaccharide Simular to Heparin **Pulmonary Embolism** **DVT**
36
**Carrageenan**
**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
**Levoglucosan**
**Carrageenan + Alkali --\> Levoglucosan** (ANHYDRO-SURGAR) * A monomeric anhydrosugar * Formed after processing Carrageenan with Alkali * BASIC CONDITIONS --\> form the levoglucosan
38

MedChem Midterm 3 (7 decks)

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