Carbohydrates 1 Flashcards

Question

**Saccharin**

Answer 1

* Artificial sweetener * *UNSTABLE when heated (not good for baking)* * Suspected to cause bladder cancer * Due to it doing so in RATS * --\> did not occur in humans * **Not metabolized in GI** * **ZERO calories** = **Suitable for diabetics**

Answer 2

**Glycoside of Stevia** * 300x sweeter than sugar BUT has BITTER aftertaste * used for diabetics

Answer 3

* **Obesity** * ****easily metabolized, few or no calories * **Diabetes** * ****Sugar intace can be controlled * ~not straightforward can cause hyperinsulinemia * **Reactive Hypoglycemia** * ****reduce absorption of glucose into blood stream --\> rapid releases of insulin * --\> lead to hypoglycemia * **Dental Care** * ****artificial sugards do NOT adhere to enamel & feed bacteria

Answer 4

* **Monosaccharides** can be combbined in MANY ways. * Each hydroxyl group can have glycosidic bond at each connection point * ALPHA OR BETA * LINEAR OR BRANCHED * **LECTINS** * proteins that bind specifically to oligosaccharide motifs and are the ones **READING** the information of the sugar code

Answer 5

**semi-synthetic disaccharide** **Ammonia Reducer / LAXATIVE** * Works by inreasing water content / volume of stools in bowel * *not absorbed in GI tract* * ****Metabolized in _distal ilium / colon_ by** **BACTERIA** to form: * **lactic acid / formic acid / acetic acid** * neutralizes ammonia (that causes encephalopathy) * --\> used in management of encephalopathy * Safe to use *EXCEPT for patients w/ b-galatoside deficiency*

Answer 6

10-100nm thick layer of **complex glycans** _cover all cells_ * **Carbohydrates for recognition & communication** * Decoded by carb binding proteins involved in pathological process * ex. recognition of viruses

Answer 7

* Main Areas: * **Inhibition of glycolytic Enzymes** (obesity) * **Inhibition of glycoside binding proteins** (infections) * *Multivalent interaction is NOT an approach* * *requires HIGH MW reagents* * *contradicts LIPINSKI's rules*

Answer 8

* Carbs have **low affinity as protein ligands** * **High Polarity****** * ****cant pass through enterocyte layer of small intestine) * **Fast Metobilites** * binding sites are filled with **water** * Unless large # of water is displaced * the free energy formation is SMALL * **HB** interactions of water and sugar are similar * Designing a drug involves appendign charged residues

Answer 9

**Reduce Postprandial HYPERglycemia** * Seek targets within the _GI tract_ & **structural mods** can be made to: * *REDUCE polarity* * *SLOW DOWN Metabolism* * **Effective in treatment of **T2Diabetes** * **Iminosugars** are effective AAI therapy * **Miglitol (Glyset)** * **Voglibose(Glustat)**

Answer 10

**Alpha Amylase Inhibitors** * **Iminosugars,** carb-based drugs * **Miglitol** is a transition state analog inhibitor * Nitrogen(-) --\> Oxocarbenium cation * in the **glycosidase reaction**

Answer 11

**Antiviral (flu A/B) Drugs** **Inhibit Viral Neuraminidase** * Carb-based drug * Start @ **Sialic Acid (N-acetylneuramic Acid)** * ****substrate of **Viral Neuraminidase** * Inhibiting this enzyme **prevents virus escape** * ****Zanamivir adds **guanidine & carboxyl residue** to oseltamivir * establishing **salt-bridge** type of interaction w/ active site * Example of drug affinity increased by fuctional group modification

Answer 12

* a **Fructan,** polymer of fructose * bears a terminal a-1 linked glucose residue on the **aglycon end** * *Not metabolized by human glycosidases* * **= soluble dietary fiber** * **broken down by _bacteria in lower gi tract_** * **Probiotic (PREBIOTIC)** * ****stimulates growth of sprophytic bacteria * *not degraded by human enzymes, is a nutrient to bacteria* * **Vaccination Ajuvant** * Inulin activates immune response * Enhances immune response to vaccine * Also used in complex w/ aluminum salts (**Algamulin)** * weakly sweet sugar \<25% of starch energy * Distributed in _Chicory, Banana, Onion, Artichoke_ * Soluble in water

Answer 13

* Carbohydrates that are NOT BROKEN DOWN or Absorbed by human digestive tract * **Dietary fiber** --\> support digestive process * Ex. **Inulin** * ****broken down in _lower GI by **bacteria**_ * result in flatulence & bloating

Answer 14

**adjunct therapy with antibiotics for UTI's** * _Cranberry juice_ contain a-mannosides @ high concentration * **A-mannosides** & **FimH** **Lectin** of the bacteria mediate the interaction between: * E.Coli -\> urinary cells * via **Fimbral adhesion proteins** * displayed on bacterial surface, act as ANCHORS

Answer 15

* = **Vaccine carrier protein** that is immunogenic yet safe in humans * Used for **SYNTHETIC VACCINES** * carbohydrate antigen is determined * Antigen is ligated --\> polypeptide * To provide **IMMUNOGENIC** component of vaccine * ability to provoke immune response * considered safer than weakened bacteria * *Issues:* * *low immunogenicity due to low antigenic mimicry by glycans*

Answer 16

Used in **Drug Delivery** * cyclic a(1,4)-linked glycans * containing 6-8 glucose residues (a, b and g). * # of GLU determine the size of hydroPHOBIC inner cavity * of cup-shaped molecules * **Solubilize drug** molecules by binding in their **hydrophobic cavity** * Nontoxic & metabolize similarly to starch * **ENHANCE drug conc. close to the membrane** * *Do NOT cross biological membranes* (large MW & Polarity), **drug does** * *****Also used as _recognition devices & scaffolds for artificial receptors_*

Answer 17

* **Enhance F & Stability** * **Stabilize flavors** * *Also used as **recognition devices & scaffolds** for artificial receptors* * Convert Liquids/Oils --\> free flowing powders * Prevent Admixture incompatibilites * REDUCE: * _Odors / taste_ * _Hemolysis / Evaporation_ * __Examples of drug CD complexes * Iodine, nicotine, nitroglycerin, OMEPRAZOLE, dexmethasone * indomethacin, HC, mitomycin

Answer 18

AKA Simple Sugars "-**OSES"** * Gluc-**ose /** Galact-**ose** / Rib-**ose** * 99% are straight chain compounds * **D-glyceraldehyde** is the simplest of the **aldoses** * Classified by presnce of **ALDEHYDE or KETONE** group * PLUS the number of **Carbons** * ****Most have **D-Configuration** * -OH group is on the right * _DOES NOT MEAN THEY ARE ALL DEXTRO_

Answer 19

**2ⁿ**= "n" is the number of stereocenters aldo**tetroses** = 2 (2¹) **pent**oses = 4 (2²) **hex**oses = 8 (2³) *think subtract 3 carbons from total carbons = n*

Answer 20

**Glu = ALL EQUITORIAL** Man = 2-axial GAL = 4-AXIAL

Answer 21

* **Pyranose form** * more stable and more sweet * **Furanose form** (5-membered ring) * ****less stable, formed when heated up

Answer 22

* **Pyranose** * ****more stable * **Furanose Form (5 membered ring)** * ****functional riboses are mainly in this form * less stable, due to steric repulsion / eclipsing

Answer 23

* **Reducing sugar** * ****There is no reducing END in the structure (end is linked) * = full acetal structure * typically seen in most other oligosaccharides * *There is no presence of a hemiacetal function* * Similar to **trehalose** (anomeric to anomeric)

Answer 24

* Monosaccharides are **DEHYDRATED** by strong acids * D-Ribose + Heat + HCL = Furfural (**THF)** * **5-hydroxymethyl furfural** * basis for MOLISCH TEST * Test that detects carbohydrates

Answer 25

* Sugars = weak acids * form **SALTS** @ HIGH pH (very basic) * --\> **1,2-Enediol Salt** is formed * Allows for interconversion of: * **D-mannose / D-Fructose / D-glucose**

Answer 26

* Sugars that are susceptible to **oxidation when heated** * in the presence of an oxidizing agent (copper sulfate) * **ALL MONOSACCHRIDES** are reducing sugars * **Raffinose is also a reducing sugar**

Answer 27

* Three enzyme systems used to measure glucose: * **Glucose Oxidase** * ****produces h2o2 * reacts w/ o-dianisidine --\> pink color * --\> D-gluconic acid = **aldonic acid (pink)** * **Glucose Dehydrogenase** * ***Hexokinase***

Answer 28

**Contain an Amino group @ 2-position** * ex. glucos**amine**, galactos**amine**, mannos**amine** * **Sialic Acid = N-acetylneuraminic acid** * 9carbon aminosurgar * constituant of bacterial peptidoglycan * important cell-wall component * ALL are constituents of _mamalian mucous membranes and tissues_

Answer 29

Monosaccharides that **lack 1+ hydroxyl groups** * **DNA**, backbone = 2'deoxyribose * **L-rhamnose** = fermatative reacgent in bacteriology * **L-fucose** * **ALMOST THE ONLY L-SUGARS in nature** * **2'3'dideoxyribose** * **= DNA polymerase chain TERMINATORS**

Answer 30

**Change from _Alpha to Beta_** * Occurs do to **acid-catalyzed reversible hemiacetal-aldehyde equilibrium** * ****starts w/ protonation of OR oxygen of hemiacital *

Answer 31

* Compounds w/ general formula **C₆H₁₂O₆** * identical to hexoses but diff chemical properties * do not have aldehyde (hemiacetal) group * Suitable as a **scaffold** for proteins or membranes * useful as **signaling molecules** * *not useful for energy storage* * *due to difficult metabolism*

Answer 32

**Codensation (release water) of 2 monosaccharides** *simultaneous dehydration* hemiacetal + alcohol --\> acetal * Most are still **Reducing sugars** * _have a reducing end on the aglycone_ * Examples: * **Sucrose** * **Lactose** * **Maltose** * cellobiose * trehalose

Answer 33

* disaccharade that hydrolyzes to: * **Glucose + Fructose (**inverted sugar) * known as table sugar * from sugar cane/sugar beat * used to make syrups (viscous) * **NON-REDUCING SUGAR** * *does not have reducing end on aglycone*

Answer 34

* disaccharide hydrolyzes to: * **glucose + galactose** * ****Milk contains alpha/beta isomers in 2:3 ratio * used in infant formulation * **LACTAID**

Answer 35

* maltose hydrolyzes to: * 2 molecules of **glucose** * (similar to cellobiose & trehalose) * aka malt sugar * germinating of barley grain * used as a **nutrient** * ovaltine, sweetener * substrate in fermenting liquor

Answer 36

* differentiate between **water soluble carbohydrate and ketone** functional groups, * A test for **reducing sugars and non-reducing sugar** * Fehling's Solution = Strong base * **KOH / NaOH / CuSO4** * ****oxidazing agent * catalyzes the ketose-aldose isomeration * --\> POSITIVE TEST FOR KETOSES & all other monosaccharides

Carbohydrates 1 Flashcards

(60 cards)