Transformation of PGI2 to 6-K-PGF1α

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Due to ring strain, PGI2 is rapidly hydrolysed to 6-keto-PGF1a. This is a non-enzymatic reaction and results in the formation of a hydroxyl group at C9 and a ketone at C6, by incorporating two hydrogens and one oxygen.

Reaction

R7 PGI2 - K6PGF2A.jpg

Chemical equation

 PGI2 \rightleftharpoons 6-K-PGF1α

Rate equation

R07.PNG

Parameters

Note that the literature values are the same as reaction 6.

Association Rate Constant (Kf)

Literature values
Value Units Conditions Substrate Weight Reference
3.7e3 ± 0.1e3 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

3 32 [1]
8.7e3 M-1 s-1 KCl (1 M)

Temperature: 25°C

3 32 [1]
1.1e4 ± 0.1e4 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

4 48 [1]
2.4 e4 M-1 s-1 KCl (1M)

Temperature: 25°C

4 48 [1]
3.7e3 ± 0.1e3 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

5 32 [1]
3.6 ± 0.2 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

6 32 [1]
1.7 ± 0.1 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

7 32 [1]
26.7 ± 0.9 M-1 s-1 NaCl04 (0.1 - 0.2 M)

Temperature: 25°C

8 32 [1]
35 M-1 s-1 KCl (1M)

Temperature: 25°C

8 32 [1]
2.25 ± 0.12 M-1 min-1 25°C, in imidazole buffer and also in phosphate buffers, CO2 to H2CO3 32 [2]
Description of the reaction 7 Kf distribution
Mode (M-1 s-1) Confidence Interval Location parameter (µ) Scale parameter (σ)
3.70E+03 3.44E+01 1.10E+01 1.66E+00
The estimated probability distribution for reaction 7 Kf. The value and weight of the literature values used to define the distribution are indicated by an orange dashed line. The x axis is plotted on a log-scale.

Dissociation Rate Constant (Kr)

This is a “Dependent parameter”, meaning that the log-normal distribution for this parameter was calculated using multivariate distributions (this is discussed in detail here). As a result, no confidence interval factor or literature values were cited for this parameter.

Description of the reaction 7 Kr distribution
Mode Location parameter (µ) Scale parameter (σ)
5.28E+01 5.63E+00 1.29E+00
The estimated probability distribution for reaction 6 Kr. The value and weight of the literature values used to define the distribution are indicated by an orange dashed line. The x axis is plotted on a log-scale.

Dissociation Constant

Literature values
Value Units Conditions Substrate Weight Reference
0.000038 mM Temperature: 35°C

Vector:Mosquito

Note: "In solution, it undergoes rapid hydrolysis to form TXB2, a stable but physiologically inactive compound." - therefore they used stable analogues.

carbocyclic TXA2 (analogue of TXA2) 24 [3]
0.00000023 mM Temperature: 35°C

Vector:Rabbit cultured astrocytes

Note: "In solution, it undergoes rapid hydrolysis to form TXB2, a stable but physiologically inactive compound." - therefore they used stable analogues.

[3H]IONO NT-126, a TXA z antagonist, 36 [4]
1500 ± 500 (excluded) mM Temperature: 25°C

In vitro

Hydroxysulfamic acid
HSA.PNG
16 [5]
H202.PNG
N/A Temperature: 20°C

In vitro

H2O2 16 [5]
5.9 E-8 N/A Oxaliplatin
Oxaliplatin.PNG
16 [6]
Description of the reaction 7 KD distribution
Mode (M-1 s-1) Confidence Interval Location parameter (µ) Scale parameter (σ)
2.35E-07 1.76E+04 -6.86E+00 2.90E+00
The estimated probability distribution for reaction 6 Kr. The value and weight of the literature values used to define the distribution are indicated by an orange dashed line. The x axis is plotted on a log-scale.

Related Reactions

References