Infrared Evidence for Collagen Structures

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71134/2/JCPSA6-22-9-1621-1.pd

AN INFRARED RAPID SCANNING SPECTROMETER AND ITS USE IN THE MEASUREMENT OF THE SPECTRA OF SHORT-LIVED MOLECULES

This work has been supported by the United States Air Force, Office of Scientific Research, Baltimore, Maryland.Author Institution: U. S. Naval Ordnance LaboratoryA rapid scanning infrared spectrometer has been designed and constructed to search for certain fundamental bands of the free radicals $NH_{2}$, $CH_{3}$, and $CH_{2}$. The monochromator uses the same off-axis parabola design as the Perkin-Elmer Mod. 12, but the Littrow mirror has been replaced by a Littrow-Wadsworth combination in which the Littrow mirror rotates continuously. The detector is a cooled lead telluride photoconductive cell. The spectrum is presented on a double beam oscilloscope. An ""optical vernier"" system synchronizes the oscilloscope sweep and also generates a set of linear fiduciary marks, each corresponding to about 4 minutes of Littrow mirror rotation, which are presented on the second trace of the oscilloscope. The radicals are generated by flash photolysis in one meter quartz absorption cell. This spectrometer is capable of scanning the 3 mu band of ammonia in about 4 milliseconds with essentially no loss in resolution from conventional slow speed, narrow band scanning, in about 2 msecs with slight loss, and in less than one msec with somewhat greater resolution loss. The results of using this instrument to search for the 3 micron bands of $NH_{2}$, $CH_{3}$, and $CH_{2}$ will be presented

INFRARED SPECTRA AND STRUCTURE OF PROTEINS

In order to throw some light on the interpretation of these spectra, observations have been made on amides and on nylon. In the former, the effects of hydrogen bonding have been found to be much more complex than was previously suspected in the region between $6\mu$ and $15\mu$; in nylon it has been found that raising the temperature causes shifts in the bands at $6\mu$ and $6.5\mu$ very similar to those attributed by others to the change in a protein from the $\alpha$ to the $\beta$ configuration. Since nylon is considered to remain in the $\beta$ configuration to high temperatures, this throws doubt on the correlation of these shifts with the transition from an $\alpha$ to a $\beta$ configuration. Experiments have been made on partially deuterating certain proteins by repeated immersion in heavy water. It is found that the bands at $3.08\mu, 3.28\mu, 6.5\mu, 8.1\mu$, and $14.2 \mu$ decrease in intensity, while increased intensity of absorption is observed at $4.15\mu$ and $6.96\mu$. Observations have also been made using polarized radiation with oriented materials. The significance of all these results on the interpretation of protein spectra will be discussed.Author Institution: Randall Laboratory of Physics, University of MichiganThe infrared spectra of 23 proteins of various types have been investigated in the range $2-15 \mu$ using a Perkin-Elmer double-beam spectrophotometer with a rock-salt prism. Although there is a considerable generation resemblance between the spectra of all the proteins, there are also marked differences, e.g., in the relative intensities of common bands and in their fine structure. Moreover, certain proteins exhibit bands not found in others. The extent to which differences in the spectra can be related to differences in amino-acid composition will be considered

Rumination, anxiety, depressive symptoms and subsequent depression in adolescents at risk for psychopathology:a longitudinal cohort study

BACKGROUND: A ruminative style of responding to low mood is associated with subsequent high depressive symptoms and depressive disorder in children, adolescents and adults. Scores on self-report rumination scales correlate strongly with scores on anxiety and depression symptom scales. This may confound any associations between rumination and subsequent depression. METHODS: Our sample comprised 658 healthy adolescents at elevated risk for psychopathology. This study applied ordinal item (non-linear) factor analysis to pooled items from three self-report questionnaires to explore whether there were separate, but correlated, constructs of rumination, depression and anxiety. It then tested whether rumination independently predicted depressive disorder and depressive symptoms over the subsequent 12 months, after adjusting for confounding variables. RESULTS: We identified a single rumination factor, which was correlated with factors representing cognitive symptoms of depression, somatic symptoms of depression and anxiety symptoms; and one factor representing adaptive responses to low mood. Elevated rumination scores predicted onset of depressive disorders over the subsequent year (p = 0.035), and levels of depressive symptoms 12 months later (p < 0.0005), after adjustment for prior levels of depressive and anxiety symptoms. CONCLUSION: High rumination predicts onset of depressive disorder in healthy adolescents. Therapy that reduces rumination and increases distraction/problem-solving may reduce onset and relapse rates of depression