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Apolipoprotein (apo) A-I, an abundant protein in high-density lipoproteins (HDL), has received considerable clinical attention as a negative predictor of coronary artery disease, because the plasma concentration of apo A-I has been shown to be inversely correlated with the incidence of coronary artery disease. A direct sandwich enzyme-linked immunosorbent assay (ELISA) for determination of the level of human serum apo A-I was developed using highly purified anti-apo A-I polyclonal antibodies raised in rabbits as the capturing antibody, and as the detecting antibody as well. Microtiter plates were coated with purified anti-apo A-I polyclonal antibodies. The concentration of apo A-I in samples was determined from the peroxidase color reaction. The sensitivity of the assay was determined to be 10 ng of apo A-I per ml of serum. The working range, where the standard curve showed a linearity, was between 10 and 100 ng/ml. The mean intra-assay and inter-assay coefficients of variation (CV) were

Levansucrase gene (levU) ofZ. mobilis had been cloned and overexpressed inEscherichia coli (Song, K.-B. and Rhee, S.-K. (1994)Biotechnol. Lett. 16, 1305–1310). The levansucrase was purified and specific antibodies against it were raised in rabbits. Specificity of the antibodies was demonstrated by Western analysis. By using the antibodies, an efficient, enzyme-linked immunosorbent assay (ELISA) amenable to immunochemical analysis of the levansucrase has been developed. The working range of levansucrase concentration in the developed ELISA was between 75 and 300 ng/ml. The assay was very sensitive to detect the levansucrase as little as 37 ng/ml.