Ala-NH M e is folded into two consecutive intramolecularly hydrogen-bonded structures of the i + 3 --+ i type (P-bends), with Aib(1)-Aib(2) and Aib(2)-P-Ala(3), respectively, as corner residues. Owing to the presence of the P-aminoacid, the latter P-bend is characterized by an unusual C,, hydrogen-bonded ring. These results indicate that: (i) a P-aminoacid may be incorporated into a Pbend without a major perturbation of the overall geometry of this folded conformation, and (ii) the propensity of the P-Ala residue for P-bend formation is rather low, unless other conformational constraints (e.g, a preceding P-bend) are present in the linear peptide molecule.P-Alanine (P-Ala; 3-aminopropionic acid) is widely distributed in the animal and plant kingdoms. Peptides containing P-Ala include homo-glutathione, carnosine, anserine, ophidine, destruxin, efrapeptin and leucinostatins.

The first X-ray diffraction structure analysis of a helical homo-peptide of Caya-dipropylglycine (Dpg) has been performed for Tfa-( Dpg),-DBH monohydrate.

The aim of this study was to compare the metabolic effects of a high-carbohydrate (CHO), high-fiber diet with only moderate protein restriction with those of a low-CHO, low-fiber diet with a low protein content in six diabetic patients with moderate chronic renal failure. The high-CHO, high-fiber diet induced a significant improvement in blood glucose control, a significant decrease in serum cholesterol, and a significant increase in fecal nitrogen losses. Other variables evaluated were not significantly different between the two diets, except for a significant increase in serum phosphorus during the high-CHO, high-fiber diet. N balance was not significantly different from 0 at the end of either dietary period and was very similar for both diets. The high-CHO, high-fiber diet presents many beneficial metabolic effects in diabetic patients with chronic renal failure.

The new platinum(II) complex of 6A,6B-diamino-6A,6B-dideoxycyclomaltoheptaose was synthesized and characterized by spectroscopy (NMR, FAB MS, UV, c.d.) and X-ray diffraction analysis. The complex crystallizes in the ortorhombic space group P2 1 2 1 2 1 with a ) 26.970(2), b ) 15.102(2), and c ) 16.142(2) Å. The Pt(II) has a square-planar coordination with two chlorine atoms and two amino groups in a cis disposition. The complexation with the Pt(II) induces a distortion of the cavity. The hydrogen bonds on the secondary hydroxyl groups, which involve the functionalized rings, are longer and consequently weaker than the other hydrogen bonds.

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