Isomers and Related Themes Flashcards
Constitutional Isomers
same molecular formula but differ in order of attached atoms
Stereoisomers
same molecular formula and attachment, but differ in spacial arrangement of those bonded groups
Enantiomers
stereoisomers that mirror images of themselves
Diastereoisomers
isomers that are not mirror images
Epimers
diastereoisomer that differs at ONE of several asymmetric carbons
example: D-glyceraldehyde and L-glyceraldehyde
Anomers
Diastereoisomers that differ at new asymmetric carbon upon ring closure
example: alpha-D-glucose and beta-D-glucose
D-glyceraldehyde, alpha D glucose, L-glyceraldehyde, beta D glucose: match the pairs and describe their commonality
D and L glyceraldehyde are epimers (differ around a single asymmetric carbon and the other two are anomers, they differ around a single carbon AFTER cyclization occurs
Aldose Ketose pairs
glucose + fructose, glyceraldehyde and dihydroxyacetone
constitutional isomers (aka aldose-ketose pairs)
AGEs
Advanced Glycation End products or Advanced Glycosylation End products
AGE formation
a) fluorescence b) protein cross linking c) loss of protein functions d) recognition by receptor for AGEs
Maillard Reaction Initiation, Propagation, Advanced Stage
Initiation: Protein + sugar
Propagation: Schiff base
Advanced stage: fluorescence, protein cross linking, loss of protein function, recognition by receptor for AGEs
Two nasty byproducts of glucose oxidation
3-deoxyglucose (3DG) and methylglyoxyl (MG)
MG + 3DG —-> products (?) name of process? proof in the body?
Enzymes break down MG and 3DG and react with them, so basically the products of glucose oxidation react with proteins and modifies them negatively
glycation
they can react with Hg to make HgA1C
Hg A1C test
Test for diabetes: hemoglobin A1C is high when their glucose is high, it means the glucose has been reacting with hemoglobin
Glycated tissues
cross linked, they don’t get disposed of and become stiff
Hyperglycemia
leads to protein glycation and potential loss of protein function in a variety of tissues (amputations for instance)
LDL
Hangs around a long time and gets oxidized. LDL just gets glycated
AGEs manifest from
glycation of proteins by carbonyl possessing compounds and aging tissues
AGEs cause
inflammation because macrophages react with them and cause inflammation cascade
monosaccharides
“polyhydroxy ketone or aldehyde”
“simple carb”
contain a lot of aldehydes and carbonyls
Disaccharides
table sugar
Polysaccharides
starch and glycogen
Hexose and “-ose”
Sugar with six carbons, ose means sugar: aldose
Pentose
5 carbon sugar:
Tetrose
4 carbon sugar
Triose
3 carbon
a sugar with an aldehyde is called an
aldose
a sugar with a ketone is called a
ketose
alpha vs beta configuration
(b UP) not (A downer)
epimeric pairs include
d-glucose and d-mannose and d-glucose and d-mannose
d-mannose and d-mannose are NOT
epimers
99.9% of glucose in the blood is
cyclized; .1 percent is in the straight chain form
cyclization
results in a configuration change around the enomeric carbon
2 prime applies to what
the epimeric carbon around which glucose and mannose, differ in hydroxyl arrangement
4 prime applies to what
the epimeric carbon around which glucose and galactose differ in hydroxyl arrangement
how does fructose relate to glucose?
aldose-ketose pair
Pyranose vs Furanose
Pyranose is a 5 carbon cyclic with oxygen at one point: the ring glucose makes after forming the hemiactetal: produces alpha and beta rings. Pryanose is another name for glucose. Pyran refers to a six membered ring strcuture
Furanose is a 5 (4 carbons plus one oxygen) membered cyclic ring that forms when ribose or fructose cyclizes with itself
Fehling’s Reagent
Clinical test for glucose in the urine. Glucose reduces copper from Cu2+ to Cu+
Glucose + Cu2+—> Cu2O + glucose
ANY reducing sugar can give a Fehling’s reagent, so it isn’t a conclusive test.
What does Fehling’s reagent test for?
a free anomeric carbon during the straight chain form of a reducing sugar: it doesn’t necessarily have to be glucose
