Amino Acids: Difference between revisions

Line 68:

==L- and D-Amino Acids==

The asymmetric α-carbon in 19 of the standard amino acids (all except glycine) is a chiral center<ref name='chirality' />. Thus, each amino acid can exist in either of two optical isomers or enantiomers (mirror images), designated the L-form and D-form. Nearly all naturally-occuring amino acids are L-amino acids, so named because they are derived from the L-form of glyceraldehyde<ref name='chirality'>See [http://en.wikipedia.org/wiki/Chirality_(chemistry) Chirality in Wikipedia]].</ref>. (Not all L-amino acids are levorotatory; some rotate polarized light clockwise<ref name='chirality' />).

Although D-amino acids are rare in nature, they do occur (see [http://en.wikipedia.org/wiki/Chirality_(chemistry)#D-Amino_Acid_Natural_Abundance natural abundance in Wikipedia]). D-alanine (DAL) occurs in over 100 entries in the [[PDB]], D-serine (DSN) in over 50, and D-methionine (MED) in over 10.

Line 83:

Line 80:

D-form

</td></tr></table>

The asymmetric α-carbon in 19 of the standard amino acids (all except glycine) is a chiral center<ref name='chirality' />. Thus, each amino acid can exist in either of two optical isomers or enantiomers (mirror images), designated the L-form and D-form. Nearly all naturally-occuring amino acids are L-amino acids, so named because they are derived from the L-form of glyceraldehyde<ref name='chirality'>See [http://en.wikipedia.org/wiki/Chirality_(chemistry) Chirality in Wikipedia]].</ref>. (Not all L-amino acids are levorotatory; some rotate polarized light clockwise<ref name='chirality' />).

Although D-amino acids are rare in nature, they do occur (see [http://en.wikipedia.org/wiki/Chirality_(chemistry)#D-Amino_Acid_Natural_Abundance natural abundance in Wikipedia]). D-alanine (DAL) occurs in over 100 entries in the [[PDB]], D-serine (DSN) in over 50, and D-methionine (MED) in over 10.

==Unusual Amino Acids==

Amino Acids: Difference between revisions

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools

@@ Line 68: / Line 68: @@
 ==L- and D-Amino Acids==
-The asymmetric &alpha;-carbon in 19 of the standard amino acids (all except glycine) is a chiral center<ref name='chirality' />. Thus, each amino acid can exist in either of two optical isomers or enantiomers (mirror images), designated the L-form and D-form. Nearly all naturally-occuring amino acids are L-amino acids, so named because they are derived from the L-form of glyceraldehyde<ref name='chirality'>See [http://en.wikipedia.org/wiki/Chirality_(chemistry) Chirality in Wikipedia]].</ref>. (Not all L-amino acids are levorotatory; some rotate polarized light clockwise<ref name='chirality' />).
-Although D-amino acids are rare in nature, they do occur (see [http://en.wikipedia.org/wiki/Chirality_(chemistry)#D-Amino_Acid_Natural_Abundance natural abundance in Wikipedia]). D-alanine (DAL) occurs in over 100 entries in the [[PDB]], D-serine (DSN) in over 50, and D-methionine (MED) in over 10.
 <table border='1' cellpadding='3' align='right'><tr><td colspan='2'>
@@ Line 83: / Line 80: @@
 D-form
 </td></tr></table>
+The asymmetric &alpha;-carbon in 19 of the standard amino acids (all except glycine) is a chiral center<ref name='chirality' />. Thus, each amino acid can exist in either of two optical isomers or enantiomers (mirror images), designated the L-form and D-form. Nearly all naturally-occuring amino acids are L-amino acids, so named because they are derived from the L-form of glyceraldehyde<ref name='chirality'>See [http://en.wikipedia.org/wiki/Chirality_(chemistry) Chirality in Wikipedia]].</ref>. (Not all L-amino acids are levorotatory; some rotate polarized light clockwise<ref name='chirality' />).
+Although D-amino acids are rare in nature, they do occur (see [http://en.wikipedia.org/wiki/Chirality_(chemistry)#D-Amino_Acid_Natural_Abundance natural abundance in Wikipedia]). D-alanine (DAL) occurs in over 100 entries in the [[PDB]], D-serine (DSN) in over 50, and D-methionine (MED) in over 10.
 ==Unusual Amino Acids==