amino acids. naturally-occurring amino acids have l-configuration ….. with only a very few having...
TRANSCRIPT
AMINO ACIDSAMINO ACIDS
H
COOH
H2N
R
AMINO ACIDSAMINO ACIDS
Naturally-occurring amino acids have L-configuration
….. with only a very few having D-configuration
the R group varies
Amino AcidsAmino Acids
D- L-
naturally-occurringamino acids are generally L-series
R R
COOH
NH2
COOH
H2NH H
H
COOH
H2N
H
glycine - the only achiral amino acid
H
COOH
H2N
CH3
alanine
H
COOH
H2N
CHCH3 CH3
valine
R = H
R = CH3
R = CH(CH3)2
20 different ones occur in proteins
SOME EXAMPLE AMINO ACIDSSOME EXAMPLE AMINO ACIDS
H
COOH
H2N
H
glycine - the only achiral amino acid
H
COOH
H2N
CH3
alanine
H
COOH
H2N
CHCH3 CH3
valine
R = H
R = CH3
R = CH(CH3)2
SOME EXAMPLE AMINO ACIDSSOME EXAMPLE AMINO ACIDS
20 different amino acids occur in proteins
They differ by the R group
THE 20 COMMON AMINO ACIDSTHE 20 COMMON AMINO ACIDSAmino acids are classified by their R group
NON-POLAR
POLAR AMINO ACIDS
•NEUTRAL
•ACIDIC
•BASIC
THE 9 NON-POLAR AMINO ACIDSTHE 9 NON-POLAR AMINO ACIDS
NH2 H
H
COOH
NH2 H
CH3
COOH
NH2 H
CH
COOH
CH3
CH3
NH2 H
CH2
COOH
CH CH3
CH3
NH2 H
CH
COOH
CH3
CH2
CH3
GlycineGly
AlanineAla
Valine*Val
Leucine*Leu
Isoleucine*Ile
NH2 H
COOH
CH2
NH2 H
COOH
CH2
NH
NH H
COOH
Phenylalanine*Phe
ProlinePro
Tryptophan*Trp
NH2 H
COOH
CH2
CH2 S CH3
Methionine*Met
* Essential amino acids
THE 6 NEUTRAL POLAR AMINO ACIDSTHE 6 NEUTRAL POLAR AMINO ACIDS
NH2 H
COOH
CH2 OH
NH2 H
COOH
CH2
OH
NH2 H
COOH
CH OH
CH3
TyrosineTyr
serine Threonine*Thr
NH2 H
COOH
CH2
CO
NH2
NH2 H
COOH
CH2
CH2
CO
NH2
NH2 H
COOH
CH2 SH
AsparagineAsn
GlutamineGln
CysteineCys
* Essential amino acid
NH2 H
COOH
CH2
COOH
NH2 H
COOH
CH2
CH2
COOH
aspartic acidAsp glutamic acid
Glu
THE ACIDIC AMINO ACIDSTHE ACIDIC AMINO ACIDS
The Two Acidics
THE BASIC AMINO ACIDSTHE BASIC AMINO ACIDS
NH2 H
CH2
COOH
CH2
CH2
CH2
NH2
NH2 H
CH2
COOH
CH2
CH2
NH
C NH
NH2
NH2 H
CH2
COOH
N
NH
Lysine*Lys
Histidine*His
Arginine*Arg
* Essential amino acids
The Three Basics
Which of the following compounds is an -amino acid?
1. Only (a)
2. (a) and (b)
3. (a) and (c)
4. (a) and (d)
Which of the following compounds is an -amino acid?
1. Only (a)
2. (a) and (b)
3. (a) and (c)
4. (a) and (d)
Which of the following amino acids is achiral?
1. Alanine 2. Aspargine3. Glycine4. Threonine
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH3 H
Alanine, Ala Glycine, Gly
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH2CNH2 CHCH3
|| |O OH
Asparagine, Asn Threonine, Thr
Which of the following amino acids is achiral?
1. Alanine 2. Aspargine3. Glycine4. Threonine
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH3 H
Alanine, Ala Glycine, Gly
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH2CNH2 CHCH3
|| |O OH
Asparagine, Asn Threonine, Thr
The amino acid shown below has a side chain that is
1. acidic2. basic3. nonpolar4. polar, neutral
The amino acid shown below has a side chain that is
1. acidic2. basic3. nonpolar4. polar, neutral
Which of the following amino acids can form hydrogen bonds between their side-chain groups?
1. Alanine and glycine2. Alanine and aspargine3. Aspargine and
threonine4. Glycine and threonine
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH3 H
Alanine, Ala Glycine, Gly
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH2CNH2 CHCH3
|| |O OH
Asparagine, Asn Threonine, Thr
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH3 H
Alanine, Ala Glycine, Gly
H O H O| || | ||
+H3N–C–C–O– +H3N–C–C–O–
| |CH2CNH2 CHCH3
|| |O OH
Asparagine, Asn Threonine, Thr
Which of the following amino acids can form hydrogen bonds between their side-chain groups?
1. Alanine and glycine2. Alanine and aspargine3. Aspargine and
threonine4. Glycine and threonine
Unusual L-Amino Acids Found in Proteins
Fig. 3-8a