@article{ref1,
title="Partial purification and characterization of 12-lipoxygenase in bullfrog erythrocytes",
journal="Comparative biochemistry and physiology. Part B, biochemistry and molecular biology",
year="2000",
author="Shen, K. and Herman, C. A.",
volume="127",
number="4",
pages="563-573",
abstract="12-Lipoxygenase (12-LO) in bullfrog (Rana catesbeiana) erythrocytes was purified partially by ion exchange chromatography and affinity chromatography. Bullfrog 12-LO was a single chain protein with a pI of 7.1-7.8 and MW of 7.77 kDa. This enzyme did not show typical Michaelis Menten type kinetics. At low substrate concentrations, it had a lag phase and at higher substrate concentrations, the activity was inhibited. The product of linoleic acid (LA), 13-hydroperoxy-9, 11-octadecadienoic acid (13-HpODE), was an activator for the enzyme. When arachidonic acid (AA) was used as substrate, 13-HpODE also affected the Km of bullfrog 12-LO towards AA. The affinity of LA towards bullfrog 12-LO was higher than the affinity of AA. Suicide inactivation was much more rapid than that of any mammalian 12-LO reported. Hemoglobin (Hb) inhibited the activity of 12-LO partially and removing Hb eliminated this inhibition. Both Hb and Met-Hb inhibited the 12-LO activity but did not denatured completely the Hb, suggesting that the inhibition was a direct interaction between 12-LO and Hb protein chain and was not due to competition between 12-LO and Hb for oxygen. This study characterizes bullfrog 12-LO with respect to stability, optimal pH, suicide inactivation and interaction with Hb and provides important evolutionary information about this enzyme.<p /><p>Language: en</p>",
language="en",
issn="1096-4959",
doi="10.1016/s0305-0491(00)00288-1",
url="http://dx.doi.org/10.1016/s0305-0491(00)00288-1"
}