A multinuclear NMR relaxation study of the interaction of divalent metal ions with L-aspartic acid.
A multinuclear NMR relaxation study of the interaction of divalent metal ions with L-aspartic acid.
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二价金属离子与 L-天冬氨酸相互作用的多核 NMR 弛豫研究。
DOI：
10.1016/0162-0134(84)85061-8
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发表时间：
1984
影响因子：
3.9
通讯作者：
Viola,RE
中科院分区：
文献类型：
--
作者：
Khazaeli,S;Viola,RE
在顺磁金属离子Cu2+和Mn2+（反磁对照Mg2+）存在的环境温度和中性ph下，测定了l -天冬氨酸、l -丙氨酸、o-磷酸-l -丝氨酸和2-巯基-l -琥珀酸水溶液的碳-13自旋晶格弛豫时间T1。在类似条件下，还测定了l -天冬氨酸的氮-15、氧-17和质子弛豫时间，o-磷酸-l -丝氨酸的磷-31弛豫时间。这些配合物在溶液中的结构是由顺磁诱导弛豫计算出的不同金属离子-核距离确定的。结果表明，Cu2+与l -天冬氨酸的配合作用主要通过α-氨基和β-羧基进行，而Mn2+与α-氨基和β-羧基的配合作用最强，并有可能通过氨基进行弱配合。对这些二价金属离子与l -天冬氨酸类似物（其中β-羧基被磷酸基（o-磷酸- l -丝氨酸）取代）的配位的研究表明，Cu2+现在可能通过α-氨基和磷酸基进行配位，而这种类似物是Mn2+通过磷酸基进行配位的单齿配体。去除β-羧基（l -丙氨酸）也导致Cu2+通过α-羧基和α-氨基进行配位，并且与Mn2+观察到相同的配体相互作用。用- SH基团（2-巯基- l -琥珀酸）取代l -天冬氨酸的α-氨基足以消除与Cu2+或Mn2+的任何特异性配位。
Carbon-13 spin-lattice relaxation times, T1, have been measured for aqueous solutions of L-aspartic acid, L-alanine,O-phospho-L-serine, and 2-mercapto-L-succinic acid in the presence of the paramagnetic metal ions, Cu2+and Mn2+, and Mg2+as a diamagnetic control, at ambient temperature and neutral pH. Nitrogen-15, oxygen-17 and proton relaxation times were also obtained for L-aspartic acid and phosphorus-31 relaxation times forO-phospho-L-serine under similar conditions. The structures of these complexes in solution were determined from the various metal ion-nuclei distances calculated from the paramagaetically-induced relaxation. These results indicate that the Cu2+interaction with L-aspartic acid is through α-amino and β-carboxyl groups while Mn2+coordinates most strongly through α-and β-carboxyl groups, with the possibility of a weak interaction through the amino group.An examination of the coordination of these divalent metal ions to an analog of L-aspartic acid in which the β-carboxyl group is replaced by a phosphate group (O-phospho-L-serine) indicated that Cu2+coordination is now probably through the α-amino and phosphate groups, while this analog is a monodentate ligand for Mn2+coordinating through the phosphate group. Removal of the β-carboxyl group (L-alanine) also results in Cu2+coordination through the α-carboxyl and α-amino groups, and the same ligand interactions are observed with Mn2+. Replacement of the α-amino group of L-aspartic acid with an - SH group (2-mercapto-L-succinate) is sufficient to eliminate any specific coordination with either Cu2+or Mn2+.