Category:BMAA

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===Definition===
 
===Definition===
 
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Except for Glycine, all amino acids contain chiral carbons, distinguished by D or L (R or S).  In the Fischer projection, which places the carboxyl group upward and amino acid-specific branch downward, the amino group must comes either left or right, protruding from the paper plane.  If the hydrogen is left and amino group is right, the amino acid is called D, after D-glyceraldehide.  If the amino group is left, it is called L.
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Except for glycine, an amino acid contains a chiral carbon, distinguished by D or L (R or S).  In the Fischer projection, which places the carboxyl group upward and amino acid-specific side-chain downward, the amino group must comes either left or right, protruding from the paper plane.  If the hydrogen is left and amino group is right, the amino acid is called D, after D-glyceraldehide.  If the amino group is left, it is called L.
 
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Glycineを除いて全てのアミノ酸は不斉炭素を持ち、D,L (R,S)の区別があります。カルボキシル基を上に、アミノ酸毎に異なる側鎖を下にしたFischer投影式を描くと、(紙面より上向きに配置される)アミノ基が左と右の場合があります。このうち水素が左アミノ基が右になるほうをD-グリセルアルデヒドに倣ってD-アミノ酸、アミノ基が左にくるものをL-アミノ酸とします。D-グリセルアルデヒドとセリンを並べてみると、DとLの理由がよくわかります。
 
Glycineを除いて全てのアミノ酸は不斉炭素を持ち、D,L (R,S)の区別があります。カルボキシル基を上に、アミノ酸毎に異なる側鎖を下にしたFischer投影式を描くと、(紙面より上向きに配置される)アミノ基が左と右の場合があります。このうち水素が左アミノ基が右になるほうをD-グリセルアルデヒドに倣ってD-アミノ酸、アミノ基が左にくるものをL-アミノ酸とします。D-グリセルアルデヒドとセリンを並べてみると、DとLの理由がよくわかります。
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===DL and RS do not coincide===
 
===DL and RS do not coincide===
 
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In the Cahn-Ingold-Prelog (or RS) notation, 19 L-amino acids become S-form (when H is placed behind the paper plane, the amino group, carboxyl group and side chain are arranged anticlockwise).  Only L-cysteine becomes R-form because S in the side chain makes the arrangement in the order of the amino group, side chain, and carboxyl group.  For this reason, although its tetrapodal configuration is the same as the rest of amino acids, it takes R-form.  For the same reason, cystine is also R-form.
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In the Cahn-Ingold-Prelog (or RS) notation, 19 L-amino acids become S-form (when H is placed behind the paper plane, the amino group, carboxyl group and side chain are arranged anticlockwise).  Only L-cysteine becomes R-form because S in its side chain makes the arrangement in the different order: amino group, side chain, and carboxyl group.  For this reason, although its tetrahedal configuration is the same as the rest of amino acids, it is R-form.  Likewise, cystine is R-form too.
 
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アミノ酸をCahn-Ingold-Prelog則(RS)により表記してみると、19のL-アミノ酸がS体となります(Hを紙面の裏側に配置したとき、アミノ基、カルボキシル基、側鎖の順にまわると左回りになる)。ただひとつL-cysteineは、側鎖にSがくるためにアミノ基、側鎖、カルボキシル基の順番に回ります。そのため正四面体構造における配置は一緒なのですが、R体となります。システインのほかにシスチンも同様の理由でR体となります。
 
アミノ酸をCahn-Ingold-Prelog則(RS)により表記してみると、19のL-アミノ酸がS体となります(Hを紙面の裏側に配置したとき、アミノ基、カルボキシル基、側鎖の順にまわると左回りになる)。ただひとつL-cysteineは、側鎖にSがくるためにアミノ基、側鎖、カルボキシル基の順番に回ります。そのため正四面体構造における配置は一緒なのですが、R体となります。システインのほかにシスチンも同様の理由でR体となります。

Revision as of 11:38, 21 May 2008


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Upper classes : BM Basic Metabolites

Contents

BMAA: Amino Acids

<p> Proteins are constituted from 20 amino acids. An amino acid has a carbon connected by an amino group and a carboxyl group (called an alpha carbon).

</p>
Straight Class
BMAAS2 Straight length 2
Gly
BMAAS2.png
BMAAS3 Straight length 3
Ser, Cys, Ala
BMAAS3.png
BMAAS4 Straight length 4
Asp, Asn, Thr
BMAAS4.png
BMAAS5 Straight length 5
Gln, Glu
BMAAS5.png
BMAAS6 Straight length 6
Lys
BMAAS6.png
Branched Class
BMAAB4 Branched length 4
Val, Met
BMAAB4.png
BMAAB5 Branched length 5
Arg, Leu, Ile
BMAAB5.png
BMAAB6 Branched length 6
BMAAB6.png
BMAACC Cyclic
Phe, Tyr, Trp, His, Pro
120px
Name Code Symbol Structure Character pI Required?
alanine Ala A -CH3 neutral 6.0
serine Ser S -CH2OH neutral 5.7
threonine Thr T -CH(OH)CH3 neutral 5.6
valine Val V -CH(CH3)2 neutral, branched 6.0
leucine Leu L -CH2CH(CH3)2 neutral, branched 6.0
isoleucine Ile I -CH(CH3)CH2CH3 neutral, branched 6.0
aspartic acid Asp D -CH2COOH acidic 2.8
glutamic acid Glu E -CH2CH2COOH acidic 3.2
asparagine Asn N -CH2CONH2 acidic, amido 5.4
glutamine Gln Q -CH2CH2CONH2 acidic, amido 5.7
lysine Lys K -(CH2)4NH2 basic 9.7
arginine Arg R -(CH2)3NHC(=NH)NH2 basic 10.8
cysteine Cys C -CH2SH neutral, S 5.1
methionine Met M -(CH2)2SCH3 neutral, S 5.7
phenylalanine Phe F -CH2-Benz neutral, aromatic 5.5
tyrosine Tyr Y -CH2-Benz-OH neutral, aromatic 5.7
tryptophan Trp W -CH2-Indole neutral, aromatic 5.9
histidine His H -CH2-Imidazole basic, atomatic 7.6
proline Pro P -NH-(CH2)3- neutral, cyclic, 2nd amine 6.2


D and L in Amino Acid

Definition

Except for glycine, an amino acid contains a chiral carbon, distinguished by D or L (R or S). In the Fischer projection, which places the carboxyl group upward and amino acid-specific side-chain downward, the amino group must comes either left or right, protruding from the paper plane. If the hydrogen is left and amino group is right, the amino acid is called D, after D-glyceraldehide. If the amino group is left, it is called L.

DL and RS do not coincide

In the Cahn-Ingold-Prelog (or RS) notation, 19 L-amino acids become S-form (when H is placed behind the paper plane, the amino group, carboxyl group and side chain are arranged anticlockwise). Only L-cysteine becomes R-form because S in its side chain makes the arrangement in the different order: amino group, side chain, and carboxyl group. For this reason, although its tetrahedal configuration is the same as the rest of amino acids, it is R-form. Likewise, cystine is R-form too.

Glycine has no chiral carbon

Glycine has two Hydrogen branches and therefore not chiral. The amino group of proline is included in the ring sturucture and therefore secondary amine.

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