Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
Homocysteine is a sulfur-containing compound produced during metabolism process of methionine. Its uptake in human plasma is believed to be the cause of cardiovascular diseases and many other diseases. An electrochemical method was proposed for selective and quantitative measurement of homocysteine by employing hydrogen sulfide sensor coupled with methionine α, γ-lyase. The principle of this method is to measure the evolved hydrogen sulfide from the enzymatic reaction between homocysteine and methionine α, γ-lyase. The sensitivities of the measurements at different pH values of the tris buffer solutions and at room temperature peaked to 275 pA/µM at pH 6.5 with detection limit of 150 nM (based on 3 σ cutoff). The linearity measurements at pH 6.5 were performed for the homocysteine concentrations range from 0.5 to 200 µM, which is wider than the human blood plasma total homocysteine level of 5 to 100 µM, and the regressive analysis of the experiments gave R2=0.9987. The enzyme also showed the fastest response to homocysteine in the tris buffer solution of pH 7.5 with the current approaching its maximum at 134 seconds. The interference tests against several common agents were carried out, and found that cysteine and methionine were the major two species to introduce measurement problem. The solution to this interference problem was explored and discussed thoroughly based on the preliminary tests. The sensitivities of the experiments against several enzyme concentrations were also performed.