Harvima R J, Harvima I T, Fräki J E
Department of Dermatology, University of Kuopio, Finland.
Clin Chim Acta. 1988 Feb 15;171(2-3):247-56. doi: 10.1016/0009-8981(88)90150-7.
The radio enzyme assay for histamine based on the transmethylation with purified histamine-N-methyltransferase and utilizing [3H-methyl]-S-adenosylmethionine as the methyl donor has been optimized to measure low histamine concentrations, for example in plasma. The pH-optimum for the assay is pH 8.3 in Tris-glycine buffer at 20 degrees C. An incubation time of 90 min is necessary using an enzyme concentration of 5.8 micrograms/ml. EDTA and dithiothreitol were included in the assay to keep the histamine-N-methyltransferase active as agents that oxidize -SH groups were found to be inhibitory to the reaction. The present assay is sensitive to about 0.5 nmol/l of histamine in a sample volume of 50 microliter (about 3 pg/sample).
基于用纯化的组胺 - N - 甲基转移酶进行转甲基作用并利用[3H - 甲基] - S - 腺苷甲硫氨酸作为甲基供体的组胺放射酶测定法已得到优化，以测量低组胺浓度，例如血浆中的浓度。该测定的最适pH为20℃时Tris - 甘氨酸缓冲液中的pH 8.3。使用5.8微克/毫升的酶浓度时，孵育时间需要90分钟。测定中加入了EDTA和二硫苏糖醇，以保持组胺 - N - 甲基转移酶的活性，因为发现氧化 - SH基团的试剂对该反应有抑制作用。本测定法对50微升样品体积中的组胺约0.5纳摩尔/升敏感（约3皮克/样品）。
