In the D form, the -OH group attached to the carbon atom adjacent to the terminal primary alcohol group ( D form attaches to the right)
In the L form the -OH group attached to the left
Pentoses are
monosaccharide class with 5 carbons
aldose = ribose
Ketoses = ribulose
Trioses are
monosaccharides with 3 carbons
aldoses = glycerose
ketoses = dihydroxyacetone
Hexoses are
monosaccharides with 6 carbons
aldoses = glucose
ketoses = fructose
stereoisomers
same chemical formula differ in the position of the hydroxyl group on one or more of the asymmetric carbons
Enantiomers
stereoisomers that are non-superimposable mirror images of each other
same connectivity
same atoms
same arrangement
Anomers
different arrangement at the carbonyl carbon ( hemiacetal or hemiketal carbon)
Epimers
stereoisomers that differ in the position of the hydroxyl (-OH) group only at one asymmetric carbon
how can monosaccharides form di-, oligo-, or polysaccharides
can be linked together through glycosidic bonds
the reaction is thermodynamically unfavored requiring activated substrates
oligo- and polysaccharides can be linked together to form
glycoproteins
Hemiacetals and Hemiketals
hemiacetals = alcohol added to aldehyde
hemiketals = alcohol added to ketone
reversiblereaction
monosaccharides with 5 or 6 atoms
five important reactions of monosaccharides
oxidation of monosacs
reduction of monosacs
phosphate ester formation
amino sugar formation
reduction of monosaccharide
reduction of the carbonyl group on a sugar produces alditols
naturally occurring ones are D-glucitol (sorbitol)
oxidation of monosaccharides
Benedicts reagent (CU2+/ OH-)
adds oxygen to carbon-hydrogen single bond of functional group
non-reducing sugars
donate electrons to other molecules
reducing sugar
sugar that has lost an OH group and is therefore a reducing agent
example of no reducing sugar
sucrose - disaccharide - aldehydic or ketonic group are bonded
What is a glycosidic bond?
A covalent bond between a sugar molecule and another molecule.
Difference between hydrolysis and dehydration?
Hydrolysis: Breaking down a compound by adding water. Dehydration: Release of water from a compound (known as condensation)
A positive iodine test means that the sample contains?
unsaturated bonds (double bonds)
What is Ammonium sulphate salt ((NH4)2SO4) used for?
used in salting protein purification to separate proteins based on their solubility in the presence of a high concentration of salt.
salt stabilizes charged groups on protein molecules and enhances the polarity of water, thus attracting protein into the solution and enhancing the solubility of protein (salt in)
a threshold is reached of salt concentration where the salt concentration is too high and proteins are no longer soluble.
salt out occurs at threshold
different proteins salt out at different concentrations
what is Column Chromatography?
a preparative technique used to purify compounds depending on their polarity
How does column chromatography work?
The protein solutionlayered on top of the column percolates into solid matrix
percolates
protein solution forms a band in the mobile phase of the collum
the more a protein interacts with the matrix, the later it will elute from the column
Quantitative Protein Assays: Analytical Techniques