Dionysius D A, Grieve P A, Vos A C
International Food Institute of Queensland, Brisbane, Australia.
J Appl Bacteriol. 1992 Feb;72(2):146-53. doi: 10.1111/j.1365-2672.1992.tb01816.x.
Components of the lactoperoxidase system were measured during incubation in Isosensitest broth, with enzymatic (glucose oxidase, GO) or chemical (sodium carbonate peroxyhydrate, SCP) means to generate H2O2. When low levels of thiocyanate (SCN-) were used in the GO system, H2O2 was detected and lactoperoxidase (LP) was inactivated when SCN- was depleted. With 10-fold higher SCN-, LP remained active and H2O2 was not detectable. The oxidation product of the LP reaction, most likely hypothiocyanite, was present in low concentrations. When SCP was used for the immediate generation of H2O2 in a system employing low SCN-, half the LP activity was lost within minutes but thereafter it remained stable. Low concentrations of oxidation product were measured and H2O2 was not detected during the course of the experiment. At high SCN- levels, relatively high concentrations of oxidation product were produced immediately, with H2O2 undetectable. The results suggest that the final product of the LP reaction depends on the method of H2O2 generation and the relative proportions of the substrates. Antibacterial activity of the two LPS was tested against an enterotoxigenic strain of Escherichia coli. Both systems showed bactericidal activity within 4 h incubation at 37 degrees C.
在伊索森西斯特肉汤中孵育期间，对乳过氧化物酶系统的成分进行了测定，采用酶促法（葡萄糖氧化酶，GO）或化学法（过碳酸钠，SCP）生成过氧化氢。在GO系统中使用低水平硫氰酸盐（SCN-）时，检测到过氧化氢，且当SCN-耗尽时乳过氧化物酶（LP）失活。当SCN-浓度高出10倍时，LP保持活性且检测不到过氧化氢。LP反应的氧化产物，很可能是次硫氰酸盐，以低浓度存在。当在使用低SCN-的系统中用SCP立即生成过氧化氢时，几分钟内LP活性丧失一半，但此后保持稳定。测定到低浓度的氧化产物，且在实验过程中未检测到过氧化氢。在高SCN-水平下，立即产生相对高浓度的氧化产物，检测不到过氧化氢。结果表明，LP反应的最终产物取决于过氧化氢的生成方法和底物的相对比例。测试了两种LPS对产肠毒素大肠杆菌菌株的抗菌活性。在37℃孵育4小时内，两个系统均显示出杀菌活性。
