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58 Cards in this Set
- Front
- Back
Glycan |
Polysaccharide |
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Glycoproteins |
“Glucose-protein” proteins with short branched carbohydrate chains bonded to the side chains of the amino acids use: receptors, recognition, interaction ex. Antigens |
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Proteoglycans (mucopolysaccharides) |
“Protein-saccharides” proteins with long, linear carbohydrate chains bonded to the side chains of the amino acids use: connecting tissues and cartilage |
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Peptidoglycans |
“Peptide-saccharides” long linear carbohydrates crosslinked by short oligopeptides use: bacteria cell wall |
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Lipopolysaccharide |
Fatty acids linked to carbohydrate use: outer envelope of gram negative bacteria |
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Carbohydrates |
“Carbon-hydrated” organic molecules mainly composed of C, H, and O |
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Simple Sugars |
Have the empirical of a carbohydrate Cn(H2O)n When in hydrated form are classified as polyhydroxyaldehydes or polyhydroxyketones ^ either are these or are molecules which form these when hydrated |
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Polyhydroxyaldehyde |
Simple sugar which when hydrated has a aldehyde functional group |
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Polyhydroxyketone |
Simple sugar which when hydrated has a ketone functional group |
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Monosaccharide |
“one-sugar” a carbohydrate that cannot be obtained via the hydrolysis of a polysaccharide or oligosaccharide |
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Polysaccharide |
“multiple-sugar” reserved for sugar linkages greater than 10 Difficult to make in the lab |
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Oligosaccharide |
“small group of-sugar” reserved for sugar linkages between 3 and 10 sugars |
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Disaccharide |
"two sugar" Two linked carbohydrates |
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Classification of saccharides |
1. By # of carbons - #—one 2. By functional group - Aldo (for aldehyde groups) = Aldose - Keto (for ketone groups, assumed position 2 is unspecified) = Ketose 3. By both - Group—#—ose - Note here that Keto can be represented instead by the ending close - Thus Ketohexose = hexulose |
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Triose |
Smallest simple sugar monomer, composed of three carbons - Can be aldotriose (aldehyde C1 or C3) or a ketotriose/triulose (ketone C2) - aldotriose has a chiral centre, triulose does not |
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Fischer Projections of saccharides |
Saccharides are often drawn in fisher and show most oxidized carbon at the top - horizontal bonds project out of the page, vertical bonds project in |
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Enantiomers |
ALL chiral centres have opposite configuration Rotate plane polarized light in opposite directions but SAME magnitude (appear LIKE mirror images) - Right is (+)- Left is (-) - this has noting to do with R/S |
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D and L naming |
Glyceraldehyde - D ia (+) rotation of PPL - L is (—) rotation of PPL Every other sugar Defined by the orientation of the furthest stereocenter from the carbonyl group (aldehyde or ketone) - Position of the OH (usually on the penultimate) - D has its OH on the right - L has its OH on the left |
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Penultimate Carbon |
Second last carbon (last chiral centre of the chain) Usually used to define the D/L orientation of a saccharide |
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Meso |
Compounds which do not rate plane polarized light (PPL) - have a plate of symmetry dividing them in half - Optically inactive |
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Rotation of Plane Polarized Light |
Only linked to D/L in glyceraldehyde Must be experimentally derived for all other sugars |
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Hemiacetal |
Product of reaction of aldehyde or ketone with alcohol in acidic or basic conditions A carbon atom is bonded to ONE heteroatom Unstable —> readily revert back to alcohol and carbonyl components |
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Conditions for hemiacetalation |
- Acidic: protonates the carbonyl and makes more electrophilic to weak OH nucleophile - Basic: deprotonates the alcohol and makes it a better nucleophile for the electrophilic carbonyl carbon (anomeric carbon) |
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Anomeric Carbon |
carbonyl carbon in a saccharide/carbohydrate new stereocenter formed here during hemiacetalation - configuration of new stereocenter determines which anomer is present (beta or alpha) |
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Anomers |
Stereoisomers differing based upon the configuration at their anomeric carbon - Beta Anomer: OH is cis to terminal CH2OH - Alpha Anomer: OH is trans to terminal CH2OH The above ONLY hold true from hemiacetals formed using penultimate carbon |
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Diastereomer |
steoisomers that differ at one or more (but not all) of their stereocenters |
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Optical Rotation |
allows us to quantify the conversion between enantiomers/ anomers |
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Mutarotation |
the process by which interconversion of a dissolved anomer results in a equilibrium mixture of both anomers (alpha and beta) Will be DIASTEREOMERS - The amount of each anomer present does not have to be equal - the final specific rotation [alpha] after can be calculated by a weighted average of the percent of each anomer present at equilibrium and their specific rotation [alpha] when pure - There will be a larger amount present of the anomer with a specific rotation further from equilibrium [alpha] in the final mixture - specific rotations must e experimentally measured |
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Glycoside |
Acetal of a sugar A carbon is bonded two two heteroatoms and two R groups - are stable in basic and neutral ph - only revert to open chain in acid and glocosidase enzyme named: sugar-ring-aside Glycosidic linkages can form between glycosides and are used to join monosaccharides together Formation requires acid and an alcohol (commonly methanol) Sn1 reaction, with carbocation intermediate A mixture of alpha and beta anomeric glycosides will form regardless of the hemiacetal we start with NO mutarotation |
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N-Glycosides |
Acetals of sugars found in nucleosides. One of the heteroatoms bonded to the anomeric carbon is a Nitrogen Nucleic acids |
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Heteroatom |
any atom that is no carbon (C) or hydrogen (H) |
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NaBH4 |
Reduces aldehydes and ketones to alcohols |
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Optically inactive product |
Product is meso (plane of symmetry) |
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D or L based on position of CH2OH |
Upwards: D Downwards: L |
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Mutarotation Vs Optical Activity |
Requirements for mutarotaion: Compound originally has chirality (not meso) and has hemiacetal If compound does not have hemicaetal it does not mean its optically inactive, it means it CANT mutarotate Compounds are optically active unless they are achiral |
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Aldonic acids |
Sugars which undergo a CHO—> COOH oxidation via a weak [O] agentSuffix “-onic” |
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Requirements for Oxidation to aldonic: |
-hemiacetal -aldehyde sugar -Weak [O] agent (strong agent with oxidize alcohols as well) |
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Reducing sugar: |
a sugar that can reduce and oxidant Must have an aldehyde group or the potential for aldehyde functionality (hemiacetal when linked) Sugars like sucrose which have an aldehyde however have no aldehyde potential due to glycosidic bond at the anomeric carbon with reduce once hydrolyzedSugar is in turn oxidized |
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Agents used in Aldonic acid oxidation: |
(1) Bromine water: - Bromine dissolved in water - Br2 is reduced to two Br- ions by the reducing sugar (2) Tollens Reagent: - [Ag(NH3)2]+ Functions as Ag+ - Oxidation is indicted by formation of silver mirror (3) Benedict’s Reagent (Feelings)- Cu2+ in citrate (benedicts) OR tartrate buffer (fellings) - Oxidation is indicted by red solid formation (Cu2O) |
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Alaric Acids: |
Sugars which undergo a CHO—> COOH oxidation AND a Primary alcohol oxidation Suffix “-aric”use nitric acid (HNO3)Done using a stronger [O] agent than Aldonic but not strong enough to oxidize secondary alcohols(primary alcohol on CH2OH) Can produce meso compounds. |
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Uronic acids: |
Sugars with ONLY the primary alcohol oxidized Aldehyde is protected during the reaction Enzyme is used for this |
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Glucuronic Acid |
The uronic acid of glucose formed via oxidation by an enzyme Will form a glycoside with toxic substances, the aldehyde makes it more water soluble and skier to excrete in urine Used by liver to detoxify This is the compound tested for in drug testing (instead of test for each parent molecule we test for glucuronic acid because we know the drugs will be bound to it) |
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Aditol: |
Sugar with reduced carbonylProduces “sugar alcohols”Reduction of ketone can result in new steeocenter Results in formation of CH2OH in place of CHO |
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Reducing agents for Aditol formation: |
Catalytic hydrogenation (H2/metal) NaBH4 LiAlH4 |
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Sugar Alcohols: |
poorly absorbed by the body Poorly metabolized #lowcal Reduction of carbonyl group |
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Alpha hydrogen: |
Hydrogen attached to carbon directly bonded to functional group(for our purposes, carbonyl group) Presence of alpha hydrogen allows for tautomerization to enol form for aldehydes and ketones |
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Epimer: |
stereoisomersdiastereomers that differ in the configuration of any one stereocenter |
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Epimerization: |
Creation of epimers via enolate formation creates and sp2 carbon (loss off stereochemistry) - Deprotonation results in spy, reprotonation can occur from either side thus results in loss of stereochemistry. |
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Tautomer: |
Constitutional isomer involving the movement of a proton (+) and a double bond position (=) |
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Isomerization: |
ene-diol rearrangement resulting in isomerization of aldehydes to ketones and ketones to aldehydes |
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Epimerization and Isomerization: |
Both occur in basic environments and so occur together. |
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Benedict’s reagent: |
weak [O] agent Used in basic (alkaline) conditions can be used to test is sugar is reducing (aldehyde) will give false positive for ketoses as it is basic and will spur isomerization reactions, changing some ketones to aldehydes, then oxidizing them. (the original sugar is not being oxidized by bennedicts, the product of a side reaction is) |
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Enol form: |
Double bond between carbonyl carbon and alpha carbon, OH where =O once was (proton shift from alpha C to carbonyl O) |
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Keto form: |
Double bonded oxygen in carbonyl group off carbonyl carbon Alpha carbon single bonded to carbonyl carbon, has H from OH in enrol form |
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Enolate: |
Deprotonated enol form |
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Aldol reaction: |
Nucleophilic addition forms new C-C bond Enolate attacks aldehyde or ketone (double bond electrons attack vagina region of aldehyde or ketone) Electrophile becomes the alcohol (enolate retains =O) Adds beta hydroxy group |
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Adolase: |
catalyzes gluconeogenisis(formation of 1,6- bisphosphate) Deprotonates DHAP, protonates GAP once attacked by DHAP |
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Retro-Adol reaction: |
glycolysis |