NMR Detection of Arginine-Ligand Interactions in Complexes of Lactobacillus casei Dihydrofolate Reductase

Gargaro, A.R.; Frenkiel, T.A.; Nieto, P.M.; Birdsall, B.; Polshakov, V.I.; Morgan, W.D.; Feeney, J.

Авторы: Gargaro A.R., Frenkiel T.A., Nieto P.M., Birdsall B., Polshakov V.I., Morgan W.D., Feeney J.
Журнал: European Journal of Biochemistry
Том: 238
Номер: 2
Год издания: 1996
Первая страница: 435
Последняя страница: 439
DOI: 10.1111/j.1432-1033.1996.0435z.x
Аннотация: 1 H-NMR and 15 N-NMR signal assignments have been made for the eight arginine residues in Lactobacillus casei dihydrofolate reductase in its binary complex with methotrexate and in its ternary complex with methotrexate and NADPH. 1 H-NMR chemical shifts for the guanidino groups of two of the arginines (Arg57 and Arg43) were sensitive to different modes of binding of the guanidino groups with charged oxygen atoms of the ligands. In the complexes formed with methotrexate, Arg57 showed four non-equivalent NHη proton signals indicating hindered rotation about the Nε -Cζ and Cζ -Nη bonds. The NHη12 and NHη22 protons showed large downfield shifts, which would be expected for a symmetric end-on interaction of these protons with the charged oxygen atoms of a carboxylate group in methotrexate. These effects were not observed for the complex formed with trimethoprim, which does not contain any carboxylate groups. In the complex formed with NADPH present, Arg43 showed a large downfield chemical shift for its NHε proton and a retardation of its rate of exchange with water. This pattern of deshielding contrasts with that detected for Arg57 and is that expected for a side-on interaction of the guanidino group protons with charged oxygen atoms of the ribose 2'-phosphate group of NADPH.
Добавил в систему: Польшаков Владимир Иванович

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NMR Detection of Arginine-Ligand Interactions in Complexes of Lactobacillus casei Dihydrofolate Reductaseстатья

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