Analytical Expressions for Isotropic Mixing in Three- and Four-Spin Topologies in13C Systems

✍ Scribed by Ananya Majumdar

• Book ID: 102593958
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 131 KB
• Volume: 121
• Category: Article
• ISSN: 1064-1858
• DOI: 10.1006/jmra.1996.0151

✦ Synopsis

An important aspect of HCCH-TOCSY-based multidimensional mixing transfers analytically, as functions of the one-bond experiments of 13 C-labeled proteins and nucleic acids is the optimicoupling J and the mixing time t. zation of the 13 C-13 C TOCSY mixing time. For this purpose, one

In this paper, analytical expressions are presented for isoneeds a description of the mixing-time dependence of the magnetitropic-mixing magnetization transfers for the spin topologies zation transfer between various spins. Here, analytical expressions shown in Table 1. These represent three-spin and linear and have been obtained for three-and four-spin systems found in branched four-spin systems relevant to amino acids. Threeamino acids, assuming isotropic-mixing conditions and a uniform spin systems have been investigated in various contexts by one-bond 13 C-13 C coupling constant. These results, which require others (9, 10) and T 12 for linear three-spin and branched analytical determination of eigenvalues and eigenvectors of the four-spin systems has been derived by Chandrakumar et al. isotropic-mixing Hamiltonian, were obtained using the program (11); all relevant transfer efficiencies are presented in this Mathematica for performing the essential linear algebra. The expressions are in complete agreement with numerical calculations work for the sake of completeness. The method used here for carried out by Eaton et al. (J. Magn. Reson. 90, 462-463, 1990

). obtaining these results is fairly straightforward, the primary From these expressions, optimum magnetization transfer efficienbottleneck being the determination of analytical eigenvalues cies for various spin topologies are easily obtained as a function and eigenvectors of the isotropic Hamiltonian, which is a of J and the mixing time t. The isotropic-mixing results agree tedious and cumbersome affair. For this purpose, the capabilreasonably well with simulations employing mixing sequences such ities of the program Mathematica (12) were exploited to as IICT-1.