专肽生物_定制多肽合成服务_多肽合成定制服务_多肽合成厂家_多肽合成公司

DABCYL‑GABA‑Ile‑His‑Pro‑Phe‑His‑Leu‑Val‑Ile‑His‑Thr‑EDANS（部分文献中也称为肾素底物 I）含有人血管紧张素原 N 端多肽中的肾素切割位点。底物特异性切割发生在亮氨酸‑缬氨酸键，对应血管紧张素原的肾素切割位点。该荧光多肽底物用于连续测量人肾素的蛋白水解活性。该检测依赖于完整底物多肽中 FRET 介导的分子内荧光淬灭。EDANS 激发态与 DABCYL 吸收的有利能量重叠以及 EDANS 荧光团相对较长的激发态寿命可实现高效荧光淬灭。肾素切割底物使肽段‑EDANS 片段脱离 DABCYL 受体附近，恢复 EDANS 部分的荧光。这导致荧光强度随时间增加，直接与底物切割程度相关。肾素催化水解该底物的动力学符合简单底物抑制模型，生理 pH 下底物 Km 约为 1.5 mM。该底物仅需孵育 3‑5 分钟即可检测低至 30 ng/mL 的肾素。

DABCYL-GABA-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Thr-EDANS (also called Renin Substrate I in some literature) contains a renin cleavage site that occurs in the N-terminal peptide of human angiotensinogen. Cleavage of the substrate occurs specifically at the Leu-Val bond and corresponds to the renin cleavage site of angiotensinogen. This fluorogenic peptide substrate is used to continuously measure the proteolytic activity of human renin. The assay relies upon FRET-mediated, intramolecular fluorescence quenching that occurs in the intact peptide substrate. Efficient fluorescence quenching occurs as a result of favorable energetic overlap of the EDANS excited state and the DABCYL absorption, and the relatively long excited state lifetime of the EDANS fluorophore. Cleavage of the substrate by renin liberates the peptidyl-EDANS fragment from proximity with the DABCYL acceptor, restoring the fluorescence of the EDANS moiety. This leads to a time-dependent increase in fluorescence intensity, directly related to the extent of substrate cleavage. The kinetics of renin-catalyzed hydrolysis of this substrate is shown to be consistent with a simple substrate inhibition model with a substrate Km approximately equal to 1.5 mM at physiological pH. The substrate can detect renin as low as 30 ng/mL after an incubation of only 3-5 min.

DABCYL标记说明

4-(4-二甲氨基苯基偶氮)苯甲酰基（Dabcyl）是一种发色团，常与荧光团（如EDANS）结合用作猝灭剂。Dabcyl/EDANS FRET（荧光共振能量转移）对的福斯特半径为3.3纳米。

4-(4-Dimethylaminophenylazo)benzoyl (Dabcyl) is a chromophor often used as a quencher in conjunction with a fluorophore (e.g., EDANS). Dabcyl/EDANS FRET pair have a Forster radius of 3.3 nm.

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Glossary: EDANS
5-[(2-Aminoethyl)amino]naphthalene-1-sulfonyl (EDANS) is fluorophor with an excitation at 340 nm ▉ and emission of 490 nm ▉. EDANS is often paired together with acceptors like dabcyl for FRET experiements.
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