Minoacids proteins and DNA
aminoacids
have an aminogroup l NHa and a carboxylgroup 1 COOH
generalstructure
organic side chain with
exceptionofglycinewhere R'is H
agpgxyj.IE É Hamino aminoacids exceptglycine are chiralmoleculesasthey hav
HAdifferentgroupsaroundcentral carbonatom rotateplanepolarisedliq
IUPAC rules fornaming
not nth in
no É ni the standard way that
a aminopropanoicacid 1,91 e.glron
are hydroxy
aminoacids are amphoteric have acidicand basic properties
amino acids sometimesexist as zwitterions have both tve and ve ions
zwitterionsonlyexist at the aminoacid's isoelectricpoint pH at which the
verage overall chargeis zero
structure
Zwitterion atisoelectric at highpH if pitishigher than
R isoelectricpointthe
t.gg IfInfngfnggwer
isoelectric o É
I it
align andIge c ni ti Nast islikelyto
g lose Ht
o is likelytoaccept Ht
ThinLayerChromatography TLC
allows toseparateandidentifyamino acids as they havedifferentsolubilities
istationaryphase silica or aluminamounted on a glass metal plate
base line drawn anddropsofaminoacidmixturesadded
placeplatein a solvent base linemustbeabovesolvent level if notsample
sots will diffuseinto solvent wash away
Leave until solvent has moved up to near the topofplate
remove mark solvent front and allow todry
amino acids most soluble in the solvent will travel further up the plate
can identify amino acids using the positions on the chromatogram
amino acids arecolourlesscompounds can be seen on chromatogramusing
worescentdyesand UV light or iodine ninhydrinsolution
fluorescentdyesand ur light
sprayentire chromatogram with fluorescentdye colourlessspotsfrom
Minoacids will block anyglow fromfluorescentdye
use UV light and draw around these spots to mark where they are
iodinein inhydrin
placechromatogram in a sealed jar with a fewiodinecrystals
iodine vapoursticks to thechemicals on the platedyingthempurple
iodinevapour locatingagent however ninhydrinsolution can beusedtoo
does not require jar hangupchromatogram in a fume cupboard andspra
inhydrin solution onto it has same effect as iodine
calculating Rf values
no of spotson plate no ofamino acids that make up the mixture
Rf valve distance travelled byspot
distance travelled by solvent
aminoacids can beidentifiedbycomparingRf valve to a libraryof knownvalve
Rfvalves fixed for each amino acid unlesschange in temp solvent or type
TLCplate
proteins
polymers of amino acid monomer unitsjoinedtogetherbypeptide links
atype of condensationpolymer
when we join 2 amino acid
no i Einen no i Itis.im itoi Itn Etntho'we form a dipeptide
ci
hydrolysis molecule
aminoacids
have an aminogroup l NHa and a carboxylgroup 1 COOH
generalstructure
organic side chain with
exceptionofglycinewhere R'is H
agpgxyj.IE É Hamino aminoacids exceptglycine are chiralmoleculesasthey hav
HAdifferentgroupsaroundcentral carbonatom rotateplanepolarisedliq
IUPAC rules fornaming
not nth in
no É ni the standard way that
a aminopropanoicacid 1,91 e.glron
are hydroxy
aminoacids are amphoteric have acidicand basic properties
amino acids sometimesexist as zwitterions have both tve and ve ions
zwitterionsonlyexist at the aminoacid's isoelectricpoint pH at which the
verage overall chargeis zero
structure
Zwitterion atisoelectric at highpH if pitishigher than
R isoelectricpointthe
t.gg IfInfngfnggwer
isoelectric o É
I it
align andIge c ni ti Nast islikelyto
g lose Ht
o is likelytoaccept Ht
ThinLayerChromatography TLC
allows toseparateandidentifyamino acids as they havedifferentsolubilities
istationaryphase silica or aluminamounted on a glass metal plate
base line drawn anddropsofaminoacidmixturesadded
placeplatein a solvent base linemustbeabovesolvent level if notsample
sots will diffuseinto solvent wash away
Leave until solvent has moved up to near the topofplate
remove mark solvent front and allow todry
amino acids most soluble in the solvent will travel further up the plate
can identify amino acids using the positions on the chromatogram
amino acids arecolourlesscompounds can be seen on chromatogramusing
worescentdyesand UV light or iodine ninhydrinsolution
fluorescentdyesand ur light
sprayentire chromatogram with fluorescentdye colourlessspotsfrom
Minoacids will block anyglow fromfluorescentdye
use UV light and draw around these spots to mark where they are
iodinein inhydrin
placechromatogram in a sealed jar with a fewiodinecrystals
iodine vapoursticks to thechemicals on the platedyingthempurple
iodinevapour locatingagent however ninhydrinsolution can beusedtoo
does not require jar hangupchromatogram in a fume cupboard andspra
inhydrin solution onto it has same effect as iodine
calculating Rf values
no of spotson plate no ofamino acids that make up the mixture
Rf valve distance travelled byspot
distance travelled by solvent
aminoacids can beidentifiedbycomparingRf valve to a libraryof knownvalve
Rfvalves fixed for each amino acid unlesschange in temp solvent or type
TLCplate
proteins
polymers of amino acid monomer unitsjoinedtogetherbypeptide links
atype of condensationpolymer
when we join 2 amino acid
no i Einen no i Itis.im itoi Itn Etntho'we form a dipeptide
ci
hydrolysis molecule
