Pollock J R, Goff H M
Department of Chemistry, University of Iowa, Iowa City 52242.
Biochim Biophys Acta. 1992 Oct 20;1159(3):279-85. doi: 10.1016/0167-4838(92)90057-k.
Products formed from the lactoperoxidase (LPO) catalyzed oxidation of thiocyanate ion (SCN-) with hydrogen peroxide (H2O2) have been studied by 13C-NMR at pH 6 and pH 7. Ultimate formation of hypothiocyanite ion (OSCN-) as the major product correlates well with the known optical studies. The oxidation rate of SCN- appears to be greater at pH < or = 6.0. At [H2O2]/[SCN-] ratios of < or = 0.5, OSCN- is not formed immediately, but an unidentified intermediate is produced. At [H2O2]/[SCN-] > 0.5, SCN- appears to be directly oxidized to OSCN-. Once formed, OSCN- slowly degrades over a period of days to carbon dioxide (CO2), bicarbonate ion (HCO3-), and hydrogen cyanide (HCN). An additional, previously unrecognized product also appears after formation of OSCN-. On the basis of carbon-13 chemical shift information this new species is suggested to result from rearrangement of OSCN- to yield the thiooxime isomer, SCNO- or SCNOH.
在pH值为6和7的条件下，通过13C-NMR对乳过氧化物酶（LPO）催化硫氰酸根离子（SCN-）与过氧化氢（H2O2）氧化反应生成的产物进行了研究。最终形成的主要产物次硫氰酸根离子（OSCN-）与已知的光学研究结果高度相关。在pH≤6.0时，SCN-的氧化速率似乎更高。当[H2O2]/[SCN-]≤0.5时，不会立即形成OSCN-，而是会产生一种未鉴定的中间体。当[H2O2]/[SCN-]>0.5时，SCN-似乎会直接被氧化为OSCN-。一旦形成，OSCN-会在数天内缓慢降解为二氧化碳（CO2）、碳酸氢根离子（HCO3-）和氰化氢（HCN）。在OSCN-形成后，还会出现另一种先前未被识别的产物。根据碳-13化学位移信息，推测这种新物质是由OSCN-重排产生硫肟异构体SCNO-或SCNOH所致。
