Oxytocin, arginine vasopressin, lysine vasopressin, arginine vasotocin, as well as their cyclic and acyclic analogs, were studied by carbon-13 nuclear magnetic resonance spectroscopy in deuterium oxide and deuterated dimethylsulfoxide. Fourier-transformed spectra were obtained at 25.16 MHz. The resonances of all carbon atoms have been assigned in both solvent systems; this includes tentative assignments of the carbonyl carbons. The spectra of arginine vasopressin and lysine vasopressin are essentially identical when compared in D2O or dimethylsulfoxide, but they differ from those of oxytocin. The spectrum of arginine vasotocin in D2O is intermediate between those of oxytocin and the vasopressins. These spectral differences are not only due to variations in constituent amino acids but are also a reflection of conformational differences of oxytocin, arginine vasotocin, and the vasopressins. All hormones are sensitive to changes in hydrogen ion concentration in both solvents; this was not observed with deamino analogs, which lack the terminal amino group.

https://www.pnas.org/content/pnas/70/7/2086.full.pdf

Conformational studies of oxytocin, lysine vasopressin, arginine vasopressin, and arginine vasotocin by carbon-13 nuclear magnetic resonance spectroscopy.

Magnetic resonance peaks have been assigned to individual protons of the constituent amino acids in the neurohypophyseal hormone, oxytocin, and in related peptides. The assignments were made possible by operation at 220 MHz with the use of variable temperature studies, proton homonuclear spin-decoupling, and comparison of spectra of oxytocin analogs. Some of the observed chemical shifts, and NH-CHα coupling constants were studied in relation to the conformation of the hormone.

http://www.pnas.org/content/64/4/1269.full.pdf

OXYTOCIN AND NEUROHYPOPHYSEAL PEPTIDES: SPECTRAL ASSIGNMENT AND CONFORMATIONAL ANALYSIS BY 220 MHz NUCLEAR MAGNETIC RESONANCE

Peptide analogues of oxytocin are described together with methods of treating conditions ameliorated by modulating oxytocin receptor. The peptide analogues are seleno or telluro peptide analogues. Methods of synthesis of selenocysteine, tellurocysteine and oxytocin analogues are also described.

Oxytocin peptide analogues

Countercurrent chromatography (CCC) is a fully automated, instrumental separation technique based on the partitioning of sample compounds in a biphasic solvent system. The separation is performed in a long and narrow tube made of Teflon or steel that is wound in several layers on a coil. Typically, two or three coils are installed in a centrifuge that is rapidly rotated during the separation. Under the impact of the centrifugal field, one phase is kept stationary, while the other is moved through the coil(s). The centrifugal forces lead to thousands of mixing and demixing steps so that CCC links the principle of repeated liquid-liquid extraction with the benefits of chromatography. CCC is widely established in the preparative purification of natural products. Typical lab-type instruments allow to inject ~ 500-mg sample, and solvent consumption is about ~ 100–500 mL. This article combines historical developments and essential basic theory with modern improvements in CCC.

Countercurrent Chromatography—When Liquid-Liquid Extraction Meets Chromatography

The sulfur atom in position 6 of deamino-oxytocin (1-β-mercapto-propionic acid-oxytocin) was replaced by selenium. The crystals of the resulting deamino-6-seleno-oxytocin are similar to those of the "wet" form of deamino-oxytocin, but they are stable upon prolonged exposure to air.

http://science.sciencemag.org/content/sci/163/3870/925.full.pdf

Oxytocin: crystal data of a seleno analog.

Conformational differences in neurohypophyseal peptides: a countercurrent distribution and partition chromatography study.

OBJECTIVES/GOALS: Our aim is to understand the role bilirubin oxidation products play in the development of cerebral vasospasm in patients with subarachnoid hemorrhage. We aim to evaluate the time course of bilirubin, HO-1, and SOD1 in relation to the subsequent development of vasospasm in to establish predictors of vasospasm development. METHODS/STUDY POPULATION: Prospective cohort observational study involving collection of CSF samples of pts admitted to KU NeuroICU with SAH and placement of EVD. CSF will be extracted from the EVD of patients on the day of placement of the EVD, and then each subsequent day for a total of 10 days. Bilirubin concentration will be determined by means of spectrophotometry. HO-1 will be measured using a commercially available ELISA kit. Cu/Zn-Superoxide Dismutase will be measured using a commercially available ELISA kit. A review of patients chart will then be performed following discharge from hospital to determine if a diagnosis of vasospasm was made, details of the vasospasm (i.e. symptoms, severity), as well as to obtain demographic data and events occurring during patients admission that could confound statistical analysis. RESULTS/ANTICIPATED RESULTS: First: we will investigate the feasibility of collecting serial CSF samples and processing them for target analyte quantification. We predict that the protocol will yield quality data that will result in insight on the pathophysiology of cerebral vasospasm. Second: we will characterize the changes in target CSF bilirubin breakdown analytes over 10 days. From this we hypothesize that as bilirubin oxidation increases, the propensity for cerebral vasospasm will also increase. DISCUSSION/SIGNIFICANCE: If there is a clear correlation between formation of bilirubin and increase in HO-1, and SOD1, with the clinical signs of vasospasm, this could be used as a biomarker for not only identifying patients at risk for developing these complications but also a means to follow the effectiveness of potential therapies.

276 Bilirubin Oxidative Products as Predictive Biomarkers of Cerebral Vasospasm: A Pilot Study

Optisch aktive selen-haltige aminosaeuren, synth. von l-selenocystin und l-selenolanthionin

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Conformational differences in neurohypophyseal peptides: a countercurrent distribution and partition chromatography study.

276 Bilirubin Oxidative Products as Predictive Biomarkers of Cerebral Vasospasm: A Pilot Study

Optisch aktive selen-haltige aminosaeuren, synth. von l-selenocystin und l-selenolanthionin