H-Gln-AMC

H-Gln-AMC is a fluorogenic substrate commenly used to measure the activity of glutaminyl cyclase (QC) enzymes with K_m value of 51 ± 3µM at pH 8.0 and k_cat value of 5.4 ± 0.1s^-1[1]. Glutaminyl cyclase (QC) catalyzes the intramolecular cyclization of N-terminal glutaminyl (Gln) and glutamyl (Glu) residues to form pyroglutamic (pGlu) peptides or proteins. Some recent findings suggest that QC can be a potential target against Alzheimer’s disease, Huntington disease and other serious neurodegenerative disease^[2].

H-Gln-AMC was used as a fluorescent substrate to detect glutaminyl cyclase (QC) activity in cerebrospinal fluid (CSF) from multiple sclerosis (MS) patients. In CSF, H-Gln-AMC was catalyzed by QC to form pyroglutamyl-AMC, which was subsequently hydrolyzed by pyroglutamyl aminopeptidase to release the fluorescent product AMC. The results show a slight increase in QC activity observed in MS patients, although the difference was not significant^[3]. H-Gln-AMC was used as a fluorescent substrate to measure the activity of glutaminyl cyclases (QCs) from Porphyromonas gingivalis (PgQC), Tannerella forsythia (TfQC), and Prevotella intermedia (PiQC). At a concentration of 50μM H-Gln-AMC, the catalytic activity of PgQC, TfQC, and PiQC could be accurately determined based on changes in AMC fluorescence intensity^[4].

References:
[1] Schilling S, Hoffmann T, Rosche F, et al. Heterologous expression and characterization of human glutaminyl cyclase: evidence for a disulfide bond with importance for catalytic activity. Biochemistry. 2002 Sep 3;41(35):10849-57.
[2] Szaszkó M, Hajdú I, Flachner B, et al. Identification of potential glutaminyl cyclase inhibitors from lead-like libraries by in silico and in vitro fragment-based screening. Mol Divers. 2017.21:175–186
[3] Gontsarova A, Kaufmann E, Tumani H, et al. Glutaminyl cyclase activity is a characteristic feature of human cerebrospinal fluid. Clin Chim Acta. 2008 Mar;389(1-2):152-9.
[4] Taudte N, Linnert M, Rahfeld J, et al.Mammalian-like type II glutaminyl cyclases in Porphyromonas gingivalis and other oral pathogenic bacteria as targets for treatment of periodontitis. J Biol Chem. 2021 Jan-Jun:296:100263.

H-Gln-AMC是一种荧光底物，通常用于测定谷氨酰环化酶（QC）酶的活性，在pH 8.0时K_m值为51 ± 3µM， k_cat值为5.4 ± 0.1s-1^[1]。谷氨酰环化酶（QC）催化n端谷氨酰（Gln）和谷氨酰（Glu）残基的分子内环化，形成热谷氨酸（pGlu）肽或蛋白质。最近的一些研究结果表明，QC可能是治疗阿尔茨海默病、亨廷顿病和其他严重神经退行性疾病的潜在靶点^[2]。

H-Gln-AMC可作为荧光底物检测多发性硬化症（MS）患者脑脊液（CSF）中谷氨酰环化酶（QC）活性。在CSF中，H-Gln-AMC经QC催化生成焦谷氨酰-AMC，经焦谷氨酰氨基肽酶水解释放荧光产物AMC。结果显示，MS患者的QC活性略有增加，但差异不显著^[3]。以H-Gln-AMC为荧光底物，检测牙龈卟啉单胞菌（PgQC），连翘单宁菌（TfQC）和中间普雷沃菌（PiQC）的QC活性。在50μM H-Gln-AMC浓度下，可以根据AMC荧光强度的变化准确判断PgQC、TfQC和PiQC的催化活性^[4]。