(426i) Integration of Relaxing Substrate Inhibition and Competitive Inhibition of Lipoxygenase by Dmf in Aerobic Catalysis | AIChE

(426i) Integration of Relaxing Substrate Inhibition and Competitive Inhibition of Lipoxygenase by Dmf in Aerobic Catalysis

Authors 

Su, Y. - Presenter, Southern Yangtze University
Zhang, Q. - Presenter, Southern Yangtze University
Xu, H. - Presenter, Southern Yangtze University
Long, H. - Presenter, Southern Yangtze University


Lipoxygenase (LOX) can catalyze
the oxidation of polyunsaturated fatty acids containing cis, cis-1,4-pentadiene
moiety to the corresponding hydroperoxides (HPOD) of conjugated (trans,
cis)-dienes. Soybean lipoxygenase was chosen as a model in this paper, the
reaction yield can be improved by dimethyl formamide (DMF), relaxing of
substrate inhibition and product inhibition. The substrate inhibition was observed
in the hydroperoxidation of linoleic acid catalyzed by soybean lipoxygenase at the
substrate concentration higher than 0.075 mmol/L . DMF (lgP=-0.81) can enhance
the substrate concentration to 232 mmol/L, and increase the hydroperoxide (HPOD) yield from 38.93%
to 66.09% as well. Lyophilization test showed that DMF
with substrate didn't affect LOX and the enzymatic activity. DMF was served as
either an activator at
low DMF level or an inhibitor at high DMF level, which was indicated by the activation constant Ka,the inhibition constant Ki and the effect of DMF with
substrate on enzymatic activity. The substrate
inhibition constant Kss at
high DMF level was increased by 1000~5600 folds compare to the control,which implied that the integration of relaxation of substrate
inhibition and competitive inhibition of lipoxygenase in DMF mediated system released the
substrate inhibition greatly together . The maximum Kss and Ki obtained at 5% DMF means that the maximum relaxation of substrate
inhibition and the minimum competitive inhibition of LOX in DMF is appeared
simultaneously.