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(d)NTP <-> (d)NMP + PPi Reactions Should Be Irreversible #527
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Here is one example for this: MAR00156 AMP [c] + PPi [c] + butyryl-CoA [c] ⇔ ATP [c] + CoA [c] + butyrate [c], while in MetatCyc curated rxn, the reaction is irreversible with the direction of ATP consumption. Please go ahead and make the changes and commits. Instead of setting the upper bound to be 0, I would suggest to revert the rxn and set the lb to be 0 and ub to be 1000 for consistence. |
I would love to, except I don't really know how; I've only ever made these changes to a local copy of Human1 using Cobrapy, and after looking at all the changes made in #525, it seems like a pretty different process than editing a Cobrapy Model object. |
@Devlin-Moyer how about first list the reactions you locally changed under this issue, probably as a table for double check |
like this?
|
great job - will look into this |
fixed in #557 |
(moved to #648) |
better move these new ones to a separate issue |
Technically, the reaction ATP + H2O <-> AMP + PPi is almost perfectly reversible at physiological temperatures and pHs, but all cells express pyrophosphatases that rapidly hydrolyze all pyrophosphate into free inorganic phosphates (PPi + H2O -> 2 Pi; a very irreversible reaction), specifically so that all of these pyrophosphate-producing reactions are driven in the pyrophosphate-producing direction and wind up being effectively irreversible (source).
In Human1, most reactions that have a (d)NTP on one side and pyrophosphate on the other are reversible, and while this is technically not wrong, it allows FBA to predict very large ATP-producing fluxes from unrealistic sources, because FBA is under no obligation to ensure that most of the pyrophosphate produced from (d)NTPs winds up going through the pyrophosphatase reactions (MAR03975, MAR03977, MAR03979, MAR06912, MAR07794) if it can also run all these ATP <-> AMP + PPi reactions in the ATP-producing direction.
There are quite a few reactions like this, so I used this bit of code to find all of them and set either the upper or lower bound to zero:
Upper Bounds Should Be Zero
MAR00156 MAR00165 MAR00168 MAR00171 MAR00174 MAR00177 MAR00180 MAR00184 MAR00188 MAR00192 MAR00196 MAR00209 MAR00213 MAR00217 MAR00226 MAR00233 MAR00237 MAR00245 MAR00249 MAR00259 MAR00267 MAR00271 MAR00279 MAR00283 MAR00293 MAR00301 MAR00305 MAR00309 MAR00313 MAR00319 MAR00323 MAR00327 MAR00331 MAR00337 MAR00341 MAR00345 MAR00349 MAR00353 MAR00357 MAR00361 MAR00365 MAR00377 MAR00397 MAR00401 MAR00405 MAR00409 MAR00413 MAR00437 MAR01157 MAR01158 MAR01159 MAR01160 MAR01200 MAR01201 MAR01202 MAR01203 MAR01263 MAR01264 MAR01265 MAR01266 MAR01290 MAR01465 MAR01532 MAR01726 MAR01727 MAR01841 MAR01842 MAR01844 MAR01848 MAR02942 MAR02943 MAR02944 MAR02945 MAR02948 MAR02949 MAR02951 MAR02952 MAR02954 MAR02956 MAR02957 MAR02961 MAR02963 MAR02965 MAR02966 MAR02967 MAR02970 MAR02971 MAR02972 MAR02973 MAR02974 MAR02975 MAR02976 MAR02977 MAR02978 MAR02979 MAR02980 MAR02981 MAR02982 MAR02983 MAR02984 MAR02985 MAR02988 MAR02991 MAR02992 MAR02994 MAR02996 MAR02998 MAR03480 MAR03482 MAR03493 MAR03797 MAR04085 MAR04086 MAR04262 MAR04401 MAR04418 MAR04452 MAR04532 MAR04536 MAR04577Lower Bounds Should Be Zero
MAR00200 MAR00204 MAR00241 MAR00255 MAR00275 MAR00289 MAR00297 MAR00369 MAR00373 MAR00381 MAR00385 MAR00389 MAR00393 MAR00417 MAR00421 MAR00425 MAR00429 MAR00433 MAR00737 MAR00740 MAR01248 MAR01249 MAR01250 MAR01251 MAR01832 MAR01833 MAR02026 MAR02120 MAR02147 MAR02946 MAR02947 MAR02955 MAR02962 MAR02964 MAR02968 MAR02969 MAR02986 MAR02987 MAR02989 MAR02990 MAR02999 MAR03000 MAR03001 MAR03002 MAR03003 MAR03387 MAR03389 MAR03489 MAR03801 MAR03803 MAR03805 MAR03846 MAR03872 MAR03874 MAR04254 MAR04257 MAR04276 MAR04460 MAR04727 MAR08990The text was updated successfully, but these errors were encountered: