Crystal structure of a three-tetrad, parallel, K+-stabilized human telomeric G-quadruplex at 1.35†Šresolution.

The crystal structure of the G-rich human telomeric DNA Tel22 has been determined at 1.35 Šresolution in space group P6. Tel22 forms a non-canonical DNA structure called the G-quadruplex. The space group and unit-cell parameters are comparable to those in the crystal structures with PDB codes 6ip3 (1.40 Šresolution) and 1kf1 (2.15 Šresolution). The G-quadruplexes are highly similar in all of the structures. However, this structure of Tel22 displays clear density for polyethylene glycol and two potassium ions, which are located outside the ion channel in the G-quadruplex and play an important role in stabilizing the crystal contacts. In addition, 111 water molecules were identified (compared with 79 and 68 in PDB entries 6ip3 and 1kf1, respectively) that participate in intricate and extensive networks providing high stability to the G-quadruplex.

Biopotency of methionine sources and their effects on sexual maturity of growing Japanese quail.

1. Japanese quail were fed on practical diets supplemented with graded amounts of DL-methionine (DL-M), DL-methionine-sodium (DL-M-Na), DL-methionine hydroxy-analogue calcium (DL-MHA-Ca) and DL-methionine hydroxy-analogue free acid (DL-MHA-FA) on an equimolar basis. 2. By the slope ratio assay using quail growth as the criterion, it was deduced that the biological activity of DL-M-Na, DL-MHA-Ca and DL-MHA-FA was approximately 0.96, 0.72 and 0.84 that of DL-M on an equimolar basis. 3. On a weight basis of the commercial products, the efficacies of DL-M-Na, DL-MHA-Ca and DL-MHA-FA were 0.38, 0.62 and 0.74, respectively. 4. Quail fed on the diet with the highest content of methionine had greater ovary weight, oviduct weight, oviduct length and egg production.