Homogeneous bioluminescence competitive binding assay for folate based on a coupled glucose-6-phosphate dehydrogenase--bacterial luciferase enzyme system

Bioluminescence immunoassay for angiotensin II using aequorin as a label

Angiotensin II is a biologically active component of the renin-angiotensin system. High levels of angiotensin II may be responsible for hypertension and heart failure because they increase systemic vascular resistance, arterial pressure, and sodium and fluid retention. Therefore, it is important to monitor angiotensin II levels for the treatment of hypertension and heart diseases. The goal of this work was to develop a bioluminescence immunoassay using aequorin as a label to measure angiotensin II levels in human plasma. This method utilizes a genetically engineered fusion protein between angiotensin II and aequorin. For that, the C terminus of angiotensin II was fused to the N terminus of apoaequorin using molecular biology techniques. A heterogeneous immunoassay was then developed for the determination of angiotensin II. A detection limit of 1 pg/mL was obtained with the optimized assay, allowing for the determination of angiotensin II at physiological levels in human plasma.

Chemiluminescence quenching of pteroic acid– N -sulfonyl-acridinium-9-carboxamide conjugates by folate binding protein

N(10)-Trifluoroacetylpteroic acid was conjugated to chemiluminescent N-sulfonylacridinium-9-carboxamide labels at the N(10) or 9-position carboxamide. Upon binding to folate binding protein the light output of the N(10) derivative (9) was quenched up to 62% upon triggering with basic peroxide, while the 9-position carboxamide conjugate (7) was quenched only 12%. The utility of this effect was demonstrated in a model homogeneous chemiluminescent assay for folic acid.