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The two reactions compared are done so using a Tanimoto similarity score (for more information, please see the MACiE FAQ) for the bond changes only. The score maay range from 0 to 1 where 1 indicates that the two reactions are identical at the bond change level and 0 indicates that there are no bond changes in common.


Key

1.0-0.9 0.9-0.8 0.8-0.7 0.7-0.6 0.6-0.5 0.5-0.4 0.4-0.3 0.3-0.2 0.2-0.1 0.1-0.0 =0

Results for Comparison of M0237 and M0090

These two reactions have a combined similarity of 0.46


M0237

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Comparison

M0090

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EC 1.5.1.33
pteridine reductase
Class EC 3.3.1.1
adenosylhomocysteinase

Image of NADPH

Image of Biopterin

Image of Proton

right arrow

Image of NADP+

Image of Tetrahydrobiopterin

2 NADPH
C00005
CHEBI:16474
Biopterin
C06313
CHEBI:15373
2 Proton
C00080
CHEBI:24636
2 NADP+
C00006
CHEBI:18009
Tetrahydrobiopterin
C00272
CHEBI:52447
0

Image of S-adenosyl-L-homocysteine

Image of water

right arrow

Image of adenosine

Image of L-homocysteine

S-adenosyl-L-homocysteine
C00021
CHEBI:57856
water
C00001
CHEBI:15377
adenosine
C00212
CHEBI:16335
L-homocysteine
C00155
CHEBI:58199

Catalytic CATH Codes

3.40.50.720

Catalytic CATH Codes

3.40.50.1480
3.40.50.720

Active Site



0.13842

Active Site



Catalytic Residues

Type Number Chain Location of Function
Arg 14 A Side Chain
Asp 161 A Side Chain
Tyr 174 A Side Chain
0.1538

Catalytic Residues

Type Number Chain Location of Function
His 54 A Side Chain
Asp 130 A Side Chain
Lys 185 A Side Chain
Asp 189 A Side Chain
Asn 190 A Side Chain
Cys 194 A Side Chain
His 300 A Side Chain
Ser 360 A Side Chain

Organic Cofactors

No Associated Organic Cofactors

Organic Cofactors

Type Identity Chain
NAD NAD 432 A

Metal Cofactors

No Associated Metal Cofactors

Metal Cofactors

No Associated Metal Cofactors

Reaction occurs across 3 steps

0.6666

Reaction occurs across 7 steps

Step 1
GIF of Reaction Step M0237.stg01

NADPH transfers a hydride to the C7 position of biopterin. The N8 position is protonated by Tyr174, which in turn is protonated by Asp161. Since Asp161 is exposed to the bulk solvent it is then protonated by water.
0.6 Step 1
GIF of Reaction Step M0090.stg01

Asp189 deprotonates Lys185, which in turn deprotonates 3'-OH of the substrate. This cause the elimination of a hydride ion, which is transferred to the NAD cofactor.
Step 2
GIF of Reaction Step M0237.stg02

The dihydrobiopterin intermediate tautomerises.
0.2 Step 2
GIF of Reaction Step M0090.stg02

Asp130 deprotonates the 4'-CH of the substrate, forming a carbanion.
Step 3
GIF of Reaction Step M0237.stg03

NADPH transfers a hydride to the C6 position of the dihydrobiopterin intermediate. The N5 position is protonated by an activated water. This water then deprotonates the 4-hydroxyl group and causes tautomerisation back to the keto-form.
0.05 Step 3
GIF of Reaction Step M0090.stg03

The 4'-carbanion initiates the elimination of the homocysteine thiolate.
Step 4
No Step with this number present
N/A Step 4
GIF of Reaction Step M0090.stg04

His54 deprotonates water, which initiates a nucleophilic attack upon the C=C in an addition reaction, re-forming the carbanion.
Step 5
No Step with this number present
N/A Step 5
GIF of Reaction Step M0090.stg05

The homocysteine thiolate deprotonates His54 in an inferred step.
Step 6
No Step with this number present
N/A Step 6
GIF of Reaction Step M0090.stg06

The carbanion deprotonates Asp130.
Step 7
No Step with this number present
N/A Step 7
GIF of Reaction Step M0090.stg07

The NAD cofactor eliminates the hydride ion, which adds to the 3'-C initiating the oxyanion to deprotonate Lys185, which in turn deprotonates Asp189.

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