Monitoring enzyme activity using a diamagnetic chemical exchange saturation transfer magnetic resonance imaging contrast agent.
Monitoring enzyme activity using a diamagnetic chemical exchange saturation transfer magnetic resonance imaging contrast agent.
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DOI：
10.1021/ja204701x
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发表时间：
2011-10-19
影响因子：
15
通讯作者：
Gilad, Assaf A.
中科院分区：
文献类型：
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作者：
Liu, Guanshu;Liang, Yajie;Bar-Shir, Amnon;Chan, Kannie W. Y.;Galpoththawela, Chulani S.;Bernard, Segun M.;Tse, Terence;Yadav, Nirbhay N.;Walczak, Piotr;McMahon, Michael T.;Bulte, Jeff W. M.;van Zijl, Peter C. M.;Gilad, Assaf A.
化学交换饱和转移（CEST）是一种产生磁共振成像（MRI）对比度的新方法，可在体内监测蛋白质特性。在这种方法中，射频用于饱和靶分子上特定质子的磁化，然后通过化学交换将其转移到水质子上并使用MRI检测。 CEST成像的一个优点是，不同质子的磁化可以在不同的共振频率下特异性饱和。这可以同时检测生物组织中的多个靶标。我们在这里提出了一种CEST MRI方法来检测胞嘧啶脱氨酶（CDase）的活性，这是一种催化胞嘧啶对尿嘧啶脱氨酸的酶。我们的发现表明，可以使用分别以+2 ppm和+2.4 ppm（相对于水）为质子的饱和脉冲（分别针对质子）来检测两种酶，胞嘧啶和5FC（5FC）的新陈代谢（5FC）。确实，重组CDase脱氨酸后，CEST对比消失了。另外，酶在三种不同的细胞系中的表达，每个细胞系的CDase水平不同，与用CEST MRI测量的CDase活性很好地一致。因此，用高分辨率CEST-MRI成像CDase活性。这些数据证明了基于质子交换的酶活性的能力。因此，CEST MRI有可能在活组织中实时遵循多种酶的动力学。
Chemical Exchange Saturation Transfer (CEST) is a new approach to generate magnetic resonance imaging (MRI) contrast that allows monitoring of protein properties in vivo. In this method, radiofrequency is used to saturate the magnetization of specific protons on a target molecule, where it is then transferred to water protons via chemical exchange and detected using MRI. One advantage of CEST imaging is that the magnetization of the different protons can be specifically saturated at different resonance frequencies. This enables the detection of multiple targets simultaneously in living tissue. We present here a CEST MRI approach to detect the activity of Cytosine Deaminase (CDase), an enzyme that catalyzes the deamination of cytosine to uracil. Our findings suggest that metabolism of two substrates of the enzyme, cytosine and 5-fluorocytosine (5FC), can be detected using saturation pulses targeted specifically to protons at +2 ppm and +2.4 ppm (with respect to water), respectively. Indeed, after deamination by recombinant CDase, the CEST contrast disappears. In addition, expression of the enzyme in three different cell lines, each with different expression levels of CDase, show good agreement with the CDase activity measured with CEST MRI. Consequently, CDase activity was imaged with high-resolution CEST-MRI. These data demonstrate the ability to detect enzyme activity based on proton exchange. Consequently, CEST MRI has the potential to follow the kinetics of multiple enzymes in real-time in living tissue.
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影响因子：
3.3
作者：
Snoussi, K;Bulte, JWM;van Zijl, PCM
通讯作者：
van Zijl, PCM
影响因子：
19.7
作者：
Arifin, Dian R.;Long, Christopher M.;Bulte, Jeff W. M.
通讯作者：
Bulte, Jeff W. M.
影响因子：
16.6
作者：
Chauvin, Thomas;Durand, Philippe;Toth, Eva
通讯作者：
Toth, Eva
影响因子：
15
作者：
Friedman, Joshua I.;McMahon, Michael T.;Stivers, James T.;Van Zijl, Peter C. M.
通讯作者：
Van Zijl, Peter C. M.
影响因子：
14.8
作者：
通讯作者：
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