Articles written in Journal of Biosciences
Volume 2 Issue 3 September 1980 pp 227-233
Intestinal brush border proteins consist of an enzymatically active hydrophilic moiety attached to a hydrophobic tail. Papain dissociates the hydrophilic part by cleaving off the hydrophobic tail, whereas the detergentTriton X-100 solubilizes the whole molecule. Denaturation by 8 M urea or 4 M guanidinium chloride does not alter the structure of the papain-solubilized enzyme. An appreciable alteration of the structure of detergent-solubilized enzyme was observed on denaturation. The difference spectra of Triton X-100 (1%)—solubilized enzyme and its urea denatured form shifts and intensifies, with increase in the concentration of the denaturant with an isobestic point at 252 nm. A new band at 280 nm also appears at 4 M urea concentration. Papain-solubilized glucoamylase has an ∞ -helical conformation in solution unlike the detergentsolubilized fraction. An elongated structure for the papain solubilized enzyme is inferred from the urea denaturation studies and from molecular weight determinations.
Volume 11 Issue 1-4 March 1987 pp 473-484
The conformation of the cyclic nonaPePtide from linseed, cyclolinoPePtide A in methanol and in acetonitrile has been elucidated by one-and two-dimensional nuclear magnetic resonance. The molecule is folded in a β-turn conformation. CyclolinoPePtide A interacts and weakly comPlexes with Tb3+ (a Ca2+ mimic ion) with the metal ion Positioned Proximally to the Phe residue, but with no substantial structural alteration uPon metal binding. CyclolinoPePtide A is also seen to aid the translocation of Pr3+ (another Ca2+ mimic) across unilamellar liPosomes. However, cyclolinoPePtide A does not Phase transfer or act as an ionoPhore of calcium ion myself. ExPeriments using lanthanide ions thus do not necessarily indicate any ionoPhoretic ability of the comPlexone towards calcium ions.