DOPA decarboxylase: Difference between revisions

Line 27:

This β-turn is comprised of residues Leu-440, Arg-441, Gly-442, and Gln-443. The distance between Cαi and Cαi+3 is 5.1Å, within the acceptable limit of 7Å. As in most β-turns, there is a hydrogen bond between the C=O of Leu-440 and the NH of Gln-443. The phi and psi angles of residues i+1 (Arg-441) and i+2 (Gly-442) are indicated in the diagram.

=====Helix Capping=====

The α helix is characterized by main chain hydrogen bonds between the C=O of residue n and the NH of residue n+4. All residues in the helix participate in this type of hydrogen bonding except the first NH groups and the last C=O groups at the ends of the helix. Helix-capping motifs are specific hydrogen bonding and hydrophobic interactions found at the ends of helices. Seven distinct capping motifs have been identified; three at the N-terminus and four at the C-terminus. Shown below is the '''capping-box''' motif found at the end of the helix composed of residues 147-171. [[image:ncap2.png|thumb|center|~~400px~~|'''capping-box''']] Here, the hydroxyl oxygen of Ser-147 forms a standard Ncap hydrogen bond with the amide of N3 (Glu-150), and the side chain carbonyl oxygen of Glu-150 forms a hydrogen bond with the amide of Ser-147. This form of special capping satisfies two of the four non hydrogen-bonded helix N-terminal amides. The side-chain capping apparent here is typical at the N-terminus. According to Aurora and Rose, this would be termed a motif Ib, N`-> N4 motif. Thus, the important hydrophobic interaction occurs between N' (Gly-146) and N4 (Ala-151).

The α helix is characterized by main chain hydrogen bonds between the C=O of residue n and the NH of residue n+4. All residues in the helix participate in this type of hydrogen bonding except the first NH groups and the last C=O groups at the ends of the helix. Helix-capping motifs are specific hydrogen bonding and hydrophobic interactions found at the ends of helices. Seven distinct capping motifs have been identified; three at the N-terminus and four at the C-terminus. Shown below is the '''capping-box''' motif found at the end of the helix composed of residues 147-171. [[image:ncap2.png|thumb|center|300px|'''capping-box''']] Here, the hydroxyl oxygen of Ser-147 forms a standard Ncap hydrogen bond with the amide of N3 (Glu-150), and the side chain carbonyl oxygen of Glu-150 forms a hydrogen bond with the amide of Ser-147. This form of special capping satisfies two of the four non hydrogen-bonded helix N-terminal amides. The side-chain capping apparent here is typical at the N-terminus. According to Aurora and Rose, this would be termed a motif Ib, N`-> N4 motif. Thus, the important hydrophobic interaction occurs between N' (Gly-146) and N4 (Ala-151).

DOPA decarboxylase: Difference between revisions

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@@ Line 27: / Line 27: @@
 This β-turn is comprised of residues Leu-440, Arg-441, Gly-442, and Gln-443. The distance between Cαi and Cαi+3 is 5.1Å, within the acceptable limit of 7Å. As in most β-turns, there is a hydrogen bond between the C=O of Leu-440 and the NH of Gln-443. The phi and psi angles of residues i+1 (Arg-441) and i+2 (Gly-442) are indicated in the diagram.
 =====Helix Capping=====
-The α helix is characterized by main chain hydrogen bonds between the C=O of residue n and the NH of residue n+4. All residues in the helix participate in this type of hydrogen bonding except the first NH groups and the last C=O groups at the ends of the helix. Helix-capping motifs are specific hydrogen bonding and hydrophobic interactions found at the ends of helices. Seven distinct capping motifs have been identified; three at the N-terminus and four at the C-terminus. Shown below is the '''capping-box''' motif found at the end of the helix composed of residues 147-171. [[image:ncap2.png|thumb|center|400px|'''capping-box''']] Here, the hydroxyl oxygen of Ser-147 forms a standard Ncap hydrogen bond with the amide of N3 (Glu-150), and the side chain carbonyl oxygen of Glu-150 forms a hydrogen bond with the amide of Ser-147. This form of special capping satisfies two of the four non hydrogen-bonded helix N-terminal amides. The side-chain capping apparent here is typical at the N-terminus. According to Aurora and Rose, this would be termed a motif Ib, N`-> N4 motif. Thus, the important hydrophobic interaction occurs between N' (Gly-146) and N4 (Ala-151).
+The α helix is characterized by main chain hydrogen bonds between the C=O of residue n and the NH of residue n+4. All residues in the helix participate in this type of hydrogen bonding except the first NH groups and the last C=O groups at the ends of the helix. Helix-capping motifs are specific hydrogen bonding and hydrophobic interactions found at the ends of helices. Seven distinct capping motifs have been identified; three at the N-terminus and four at the C-terminus. Shown below is the '''capping-box''' motif found at the end of the helix composed of residues 147-171. [[image:ncap2.png|thumb|center|300px|'''capping-box''']] Here, the hydroxyl oxygen of Ser-147 forms a standard Ncap hydrogen bond with the amide of N3 (Glu-150), and the side chain carbonyl oxygen of Glu-150 forms a hydrogen bond with the amide of Ser-147. This form of special capping satisfies two of the four non hydrogen-bonded helix N-terminal amides. The side-chain capping apparent here is typical at the N-terminus. According to Aurora and Rose, this would be termed a motif Ib, N`-> N4 motif. Thus, the important hydrophobic interaction occurs between N' (Gly-146) and N4 (Ala-151).