A set of benzoxazolyl-l-alanine derivates along with the MCA moiety (donors of fluorescence) were introduced into a proteinase 3 (PR3) substrate with a C-terminal ANB-NH2 that serves as a fluorescence acceptor. Five substrates with general formula X-Tyr-Tyr-Abu-ANB-NH2 were synthesized, and their kinetic parameters against proteinase 3 were determined. The highest kcat/KM value, 1.5 × 106 M−1 s−1, was obtained for (Pyr)Box-Ala-Tyr-Tyr-Abu-NH2 where (Pyr)Box-Ala stands for N-methylpyrrole benzoxazole-l-alanine. Titration of this peptide with proteinase 3 resulted in measurable fluorescence at an enzyme amount equal to 29 pmol. This substrate was selected used to detect quantifiable levels of proteinase 3 in serum samples, including those of normal subjects. For all c-ANCA-positive samples (diagnosed Wegener granulomatosis), a significant increase of PR3 concentration was observed. Wegener granulomatosis is a severe autoimmune disease causing inflammation of the blood vessels. Our results clearly show that this substrate can be used for the construction of a very reliable, inexpensive, and easy to use diagnostic test for PR3 determination.
一组苯并
噁唑基-l-丙
氨酸衍
生物与MCA基团(荧光供体)被引入到具有C端ANB-NH2的
蛋白酶3(PR3)底物中,该底物作为荧光受体。合成了五种一般式为X-Tyr-Tyr-Abu-ANB-NH2的底物,并确定了它们对
蛋白酶3的动力学参数。得到的最高kcat/KM值为1.5 × 10^6 M−1 s−1,出现在(Pyr)Box-Ala-Tyr-Tyr-Abu-NH2中,其中(Pyr)Box-Ala代表
N-甲基吡咯烷苯并
噁唑-l-丙
氨酸。用
蛋白酶3对该肽进行滴定,在酶量为29 pmol时观察到了可测量的荧光。选择该底物用于检测血清样本中
蛋白酶3的定量
水平,包括正常受试者的样本。对于所有c-ANCA阳性样本(诊断为韦格纳肉芽肿病),观察到PR3浓度显著增加。韦格纳肉芽肿病是一种严重的自身免疫疾病,会导致血管炎症。我们的结果清楚地表明,这种底物可以用于构建一种非常可靠、廉价且易于使用的PR3检测诊断测试。