Terahertz spectroscopy of bacteriorhodopsin and rhodopsin: similarities and differences.

We studied the low-frequency terahertz spectroscopy of two photoactive protein systems, rhodopsin and bacteriorhodopsin, as a means to characterize collective low-frequency motions in helical transmembrane proteins. From this work, we found that the nature of the vibrational motions activated by terahertz radiation is surprisingly similar between these two structurally similar proteins. Specifically, at the lowest frequencies probed, the cytoplasmic loop regions of the proteins are highly active; and at the higher terahertz frequencies studied, the extracellular loop regions of the protein systems become vibrationally activated. In the case of bacteriorhodopsin, the calculated terahertz spectra are compared with the experimental terahertz signature. This work illustrates the importance of terahertz spectroscopy to identify vibrational degrees of freedom which correlate to known conformational changes in these proteins.

Magnetic form factor of nickel determined by white beam x-ray diffraction.

The magnetic form factor of nickel has been measured, as a fraction of the charge form factor for {h00} and {hhh} reflections up to (10 00) and (666), by an x-ray energy dispersive white beam technique that uses elliptically polarized synchrotron radiation and single crystal samples. At low sin(θ)/λ the results are in good agreement with theory and with the values determined from neutron studies. The measurements extend beyond the current range of neutron data and indicate that significant magnetic diffraction effects are observable at sin(θ)/λ > 1.5 Å-1 if photons with energies above 26 keV can be used.

MRI CT, and plain film appearance of anterior spina bifida.

Anterior spina bifida or butterfly vertebral body has a well known and characteristic appearance on plain film and CT. Its appearance on magnetic resonance imaging also appears to be characteristic and should not be mistaken for more serious abnormalities.

Synthesis and some biological properties of 6-aminopenicillanic derivatives.

The properties of 33 6-aminopenicillanic derivates were described, the majority of which and particularly all 3,4-disubstituted phenyl derivatives, are new compounds. These derivatives were synthesized by three different methods consisting in treating of 6-aminopenicillanic acid (6-APA) with appropriate phenylthio -- and phenoxyalkanecarboxylic acids. The method consisting in use of aryloxyketenes is new and claimed by the patent applications. All synthesized compounds were screened for their biological activity against 21 different strains of pathogenic microorganisms of species: Staphylococcus, Sarcina, Streptococcus, Escherichia, Proteus, Klebsiella, Neisseria, Pseudomonas, Bacillus subtilis and Candida albicans. In the present paper only the most interesting results of microbiological tests and some data concerning pharmacological investigations performed on rats, were presented. Among selected compounds both substances 30 and 32 showed animals weight growth stimulating activity.

Modification of 6-aminopenicillanic acid derivatives.

In order to prepare intermediate for further transformation of penicillins), and to obtain new derivatives with enlarged spectrum of biological activity some semi-synthetic phenoxyalkanepenicillins were subjected to the esterification, amidation and hydroxyamidation reactions. Hydroxyamidation i.e. synthesis of corresponding penicilline-hydroxamic acids was a complex reaction depending on the structure of hydroxylamine used. The two-directional reaction course, with beta-lactam bond splitting, was specific for unsubstituted hydroxylamine only. A number of new penicilline hydroxamic acids and N-methoxypenicilline amides, with intact and cleaved beta-lactam ring were synthesized.