Kingsley P B, Monahan W G
Department of Radiology, North Shore University Hospital, 300 Community Drive, Manhasset, New York, 11030 USA.
J Magn Reson. 2000 Sep;146(1):100-9. doi: 10.1006/jmre.2000.2124.
The effects of incomplete saturation and off-resonance irradiation on nuclear magnetic resonance saturation-transfer measurements of three-site chemical-exchange rates are discussed. A new method that uses double-saturation measurements is compared with two published methods, one that uses single-saturation measurements and one that uses a single-saturation measurement and a double-saturation measurement. Several formulas are compared for measuring the exchange rate constant k(DE) for exchange from a detected spin D to an exchanging spin E in the presence of exchange from spin D to a competing spin C. For each method, formulas are derived with corrections for incomplete saturation or off-resonance effects, with both corrections, and with neither correction. Exact formulas are available for three exchanging sites with incomplete saturation if there are no off-resonance effects. Off-resonance corrections are imperfect even with complete saturation.
讨论了不完全饱和和失谐辐照对三位点化学交换速率核磁共振饱和转移测量的影响。将一种使用双饱和测量的新方法与两种已发表的方法进行了比较，一种使用单饱和测量，另一种使用单饱和测量和双饱和测量。比较了几个用于测量在自旋D与竞争自旋C发生交换的情况下，从检测到的自旋D到交换自旋E的交换速率常数k(DE)的公式。对于每种方法，都推导了针对不完全饱和或失谐效应的校正公式、同时包含这两种校正的公式以及不进行任何校正的公式。如果不存在失谐效应，对于具有不完全饱和的三个交换位点，可以得到精确公式。即使完全饱和，失谐校正也并不完美。
