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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 M0268 and M0062

These two reactions have a combined similarity of 0.28


M0268

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Comparison

M0062

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EC 2.1.1.13
methionine synthase
Class EC 5.4.99.2
methylmalonyl-CoA mutase

Image of L-Homocysteine

Image of 5-Methyltetrahydrofolate

right arrow

Image of L-Methionine

Image of Tetrahydrofolate

L-Homocysteine
C00155
CHEBI:58199
5-Methyltetrahydrofolate
C00440
CHEBI:18608
L-Methionine
C00073
CHEBI:57844
Tetrahydrofolate
C00101
CHEBI:26907
0

Image of succinyl-CoA

right arrow

Image of (R)-2-methyl-3-oxopropanoyl-CoA

succinyl-CoA
C00091
CHEBI:57292
(R)-2-methyl-3-oxopropanoyl-CoA
C01213
CHEBI:57327

Catalytic CATH Codes

3.40.50.280

Catalytic CATH Codes

3.20.20.240
3.40.50.280

Active Site



0.41895

Active Site



Catalytic Residues

Type Number Chain Location of Function
His 759 A Side Chain
Asp 757 A Side Chain
Ser 810 A Side Chain
0.4285

Catalytic Residues

Type Number Chain Location of Function
Tyr 89 A Side Chain
His 244 A Side Chain
Lys 604 A Side Chain
Asp 608 A Side Chain
His 610 A Side Chain

Organic Cofactors

Type Identity Chain
methylcobalamin Cob 122 A

Organic Cofactors

No Associated Organic Cofactors

Metal Cofactors

Type Het group Number Chain
cobalt COB 122 A

Metal Cofactors

Type Het group Number Chain
cobalt B12 800 A

Reaction occurs across 3 steps

0.2812

Reaction occurs across 6 steps

Step 1
GIF of Reaction Step M0268.stg01

The sulfur of homocysteine initiates a nulceophilic attack on the methyl of methylcobalamin, forming Co(I)alamin and the methionine product in a substitution reaction. A proton relay between His759 and bulk solvent modulates the reactivity of the cobalamin cofactor.
0 Step 1
GIF of Reaction Step M0062.stg01

The Co(II)-C bond of the B12 cofactor undergoes homoloysis, forming the adenosyl radical and Co(I).
Step 2
GIF of Reaction Step M0268.stg02

The cob(I)alamin initiates a nucleophilic attack on the methyl group of methyltetrahydrofolate, proceeding through a three centre two electron bond, to form the methylcobalamin and covalently bound tetrahydrofolate.
0 Step 2
GIF of Reaction Step M0062.stg02

The adenosyl radical abstracts a hydrogen from the substrate.
Step 3
GIF of Reaction Step M0268.stg03

The tetrahydrofolate product dissociated from the cobalamin cofactor with concomitant protonation (assumed to be from the bulk solvent).
0 Step 3
GIF of Reaction Step M0062.stg03

The substrate radical attacks its own carbonyl carbon, forcing the radical onto the oxygen, which deprotonates His244.
Step 4
No Step with this number present
N/A Step 4
GIF of Reaction Step M0062.stg04

His244 deprotonates the oxygen, which causes radical rearrangement and the cleavage of the propane ring formed, the radical ends up on the newly formed CH2 branch.
Step 5
No Step with this number present
N/A Step 5
GIF of Reaction Step M0062.stg05

The substrate radical abstracts a hydrogen from the adenosine, re-forming the adenosyl radical.
Step 6
No Step with this number present
N/A Step 6
GIF of Reaction Step M0062.stg06

The adenosyl radical and Co(I) undergo colligation, reforming the B12 cofactor.

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