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l-Aminocycloheptanecarboxylic acid hydrobromide monohydrate crystallizes in space group P212121 with cell dimensions a = 25.69, b = 6-85 and c = 6.6t . The structure was solved in the hkO and hOl projections, and refined with the three-dimensional data to an R factor of 9'86%. The cycloheptane ring is disordered, which leads to 'predominant' and 'alternative' conformations. Both of these conformations correspond to a skew-chair form. The structure is stabilized by a threedimensional network of hydrogen bonds.

Crystals of 1-aminocyclooctanecarboxylic acid hydrobromide are orthorhombic, witha= 26·026,b=7·087,c= 6·149,Z= 4 and space groupP212121.The structure was solved in projections by direct methods and later refined with three-dimensional data using a full-matrix least-squares treatment. All hydrogen atoms were located from a difference Fourier and the finalRfactor for the 1128 observed reflections was 8·62 %. The molecules are held together by a series of hydrogen bonds in a three-dimensional network. A detailed discussion of the intramolecular and the intermolecular features of the structure is presented. The cyclooctane ring is found to exist in theboat-chair conformation.

The circular dichroism spectra of the ferri- and ferrocytochromes c derived from horse, beef, chicken, and turtle hearts have been measured over the wavelength range of 240-185 mμ. The spectra in this wavelength region of the ferri and ferro forms appear to be the same within experimental error and indicate that no gross conformational differences appear to exist between the oxidized and reduced forms. The upper limit of the apparent helix content has been estimated to be about 17% with a lower limit in the neighborhood of 10%. The presence of circular dichroism bands characteristic of α-helix conformations are observed along with bands characteristic of β structure. These data strongly suggest the presence of a small but real helical segment (s) in cytochrome c .

1-aminocyclopentane carboxylic acid monohydrate is monoclinic: space groupP21/c,a = 11·24,b = 6·27,c = 11·22 A and β = 97·6 °. The crystal structure was solved by the symbolic addition method and refined to anR factor of 12·1%. The cyclopentane ring is disordered; one of the carbon atoms exists in two alternative sites, leading to two possible conformations both of which are of the envelope type.

1-aminocyclohexane carboxylic acid hydrochloride crystallizes in the monoclinic space group P2 1 with unit cell dimensions a=9·36, b=6·40, c=7·40A and β=96·0°. The structure has been solved by beta synthesis and refined three-dimensionally to an R factor of 10·9% with 817 observed re-flexions. The conformation of the cyclohexane ring is a slightly distorted chair.

The pH dependence of the conformation of concanavalin A has been studied by means of optical rotatory dispersion and circular dichroism spectroscopy. At pH 2.9, 5.0, and 7.0, the major contribution to organized structure appears to be the β conformation. At pH 9.1, the conformation of concanavalin A approaches the random coil or unordered form. No evidence could be found for the presence of any significant amount of α helix. The pH of maximum precipitin-like activity of concanavalin A is paralleled by the pH dependence of the parameter b 0 in the Moffitt equation.