MAGNETIZATION TRANSFER IN CROSS-LINKED BOVINE SERUM-ALBUMIN SOLUTIONS AT 200 MHZ - A MODEL FOR TISSUE
MAGNETIZATION TRANSFER IN CROSS-LINKED BOVINE SERUM-ALBUMIN SOLUTIONS AT 200 MHZ - A MODEL FOR TISSUE
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DOI：
10.1002/mrm.1910290306
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发表时间：
1993-03-01
影响因子：
3.3
通讯作者：
UGOLINI, R
中科院分区：
文献类型：
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作者：
KOENIG, SH;BROWN, RD;UGOLINI, R
我们报告的结果质子1/T1，1/T2，和K，从溶剂到溶质的磁化转移率，为5和10 wt.在4.7 T（200.1 MHz）和19°C下，天然和化学交联的牛血清白蛋白在未氘化和50%氘化水中的%溶液。在该磁场下，尽管交联样品的K> 1/T1，但磁化转移对1/T1的直接贡献很小。因此，使用蛋白质质子的非共振辐射测量K。所有样品的数据可以使用磁化转移的理论模型拟合，具有三个参数：溶质和溶剂质子的固有纵向弛豫速率，和K。K的量级如此之大，以至于新发现的长寿命（101 μs）水合位点（S。H.凯尼希河D. Brown III和R.乌戈利尼，马格纳斯。医学、29，77（1993））必须被援引来解释K，因为这对于解释交联对质子和氘核的1/T1的磁场依赖性的不同影响以及固定化系统中低于20 MHz的大1/T1和1/T2值是必要的。虽然这些位点的数量很少，但它们的长驻留寿命成为蛋白质固定化时磁化转移的相关时间，从而解释了K值的大值。来自几个实验室的最新数据表明，这里使用的交联蛋白是组织1/T1和1/T2的良好模型，作为温度和磁场的函数。
We report results for proton 1/T1, 1/T2, andK, the rate of magnetization transfer from solvent to solute, for 5 and 10 wt. % solutions of bovine serum albumin, both native and chemically cross‐linked, in undeuterated and ∼50% deuterated water, at 4.7 T (200.1 MHz) and 19°C. At this field, althoughK> 1/T1for the cross‐linked samples, magnetization transfer contributes little to 1/T1directly. ThereforeKwas measured using off‐resonance irradiation of the protein protons. The data for all the samples can be fit using a theoretical model for magnetization transfer, with three parameters: the intrinsic longitudinal relaxation rates of solute and solvent protons, andK. The magnitude ofKis so large that the newly‐identified, long‐lived (∼1 μs) hydration sites (S. H. Koenig, R. D. Brown III, and R. Ugolini, Magn. Reson. Med., 29, 77 (1993)) must be invoked to account forK, as is necessary to explain the differential effects of cross linking on the magnetic field dependence of 1/T1of protons and deuterons and the large 1/T1and 1/T2values below ∼20 MHz in immobilized systems. Although these sites are few in number, their long resident lifetime becomes the correlation time for magnetization transfer when protein is immobilized, accounting for the large value ofK. Recent data from several laboratories have shown that cross‐linked protein, as used here, is a good model for 1/T1and 1/T2of tissue, as a function of temperature and magnetic field.