Derivatives and kinetics of lactoperoxidase

Publisher Website
Google Scholar
Abstract
A spectrophotometric method of measuring activity of lactoperoxidase using pyrogallol as hydrogen donor is descr. The conditions of measurement are such that, with high donor concn. and low peroxide concn., the reaction of enzyme with peroxide is measured. A brief descr. is given of the prepn. of lactoperoxidase of high spectroscopic purity in the visible region of the spectrum and of 40-50% absolute purity. The absorption curves in the visible and Soret regions are given for lactoperoxidase and its carbon monoxide-, cyanide-fluoride-, and pyridine-hemo-chromogen derivatives. The absorption spectra are very similar in pattern to those for the protohematin compounds, horse-radish peroxidase, catalase and methemoglobin. The prosthetic group of lactoperoxidase is probably a hematin closely related to protohematin. The absorption bands of lactoperoxidase and of its derivatives lie further to the red than the protohematin enzymes indicating that the prosthetic group is not identical with protohematin. The kinetics of lactoperoxidase were examined mathematically using the mechanism of peroxidase action descr. by Chance and modified by George. The Michaelis constant (1.08 x 10-3[image]) was detd. experimentally and found to be in good agreement with the value calculated by Chance.
Keywords