Peptidyl-prolyl-cis-traps isomerase (PPIase) catalyzes the cis-trans isomerization of prolyl peptide bonds in polypeptides and the foldeng process of proteins. This protein was known to be cyclophilin which has high binding affinity for cyclosporin A, a cyclic undecapeptide of fungal origin with potent immunosuppressive agent. The primary structure of the peptidyl-prolyl isomerase a was determined from analysis of peptides derived by lysyl endopeptidase digestion, Staphylococcus aureus V8 digestion, cyanogen bromide cleavage and N-terminal sequence of the protein. The protein with a calculated molecular mass of 19.7 kDa consisting of 179 amino acids from the established complete sequence. The comparison of the amino acid sequence of peptidylprolyl-isomerase from Fusarium with that from Nucerospora crassa revealed significant degree of amino acid sequence similarity
Employing monoclonal antibody (mAb) AL. 2 reactive for aflatoxin B1-lysin adducts (AFB1-Lys), biotin-conjugated affinity purified anti-human serum albumin (HSA) antibody, and streptoavidin-conjugated horseradish peroxidase (HRP), the sandwich ELISA (sELISA) AFB1-HSA adducts was constructed. In this sELISA, AFB1-HSA adducts in crude albumin fraction were detected as low as 5pg AFB1-Lys equivalent/mg HSA without pronase digestion. Since the present sELISA is not requested for an enzymatic hydrolysis of HSA, more than 150 serum samples could be analyzed in one week. AFB1-HSA analysis of 70 human sera sampled during 1986-1994 in Haimen (China), a high endemic area of primary liver cancer (PLC), revealed that 20-70% of the sera were positive for AFB1-HSA adducts. The case-control study on 137 sera (69 controls and 68 cases of PLC) collected in 1994 revealed no significant difference both in the positivity and the average level. As for 100 sera (44 controls and 56 cases) sampled in 1995, the postivity for AFB1-HSA in the cases was significantly higher than that in the controls, although no difference in their contents was observed.
Aflatoxin B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) were analyzed by thermospray liquid chromatography/mass spectrometry. The ionization efficiency of each aflatoxins (AFs) was stongly affected by the temperatures of the tip point of the vaporizer probe (TIP) and the vapor temperature. By controlling the vapor temperature rather than the TIP temperature, more stable analytical conditions were achieved. The strongest ions of each of the AFs were (M+H)+ followed by (M+NH4)+ and (MH-44)+ and the ratios of these ions were changed by ionization mode. The minimum quantitative limits of AFs were one ng using selected ion monitoring chromatography. The quantitative determination of the four AFs were linear up to 1000 ng. No interference peaks were observed at M/Z 313, 315, 329 and 331, which correspond to (M+H)+ of AFB1, AFB2, AFG1 and AFG2, from samples of maize, peanut meal and mold culture extracts. The minimum quantitative limits of aflatoxins in these samples were about 10 ppb.