Electronic and Vibrational Optical Activity of Several Peptides Related to Neurohypophyseal Hormones: Disulfide Group Conformation Marke ´ta Pazderkova ´, 1,2 Lucie Bedna ´rova ´, 1 Helena Dlouha ´, 1 Martin Flegel, 1,3 Michal Lebl, 4 Jan Hlava ´c ˇek, 1 Vladimı´rSetnic ˇka, 5 Marie Urbanova ´, 5 Sixtus Hynie, 3 Ve ˇra Klenerova ´, 3 Vladimı´rBaumruk, 2 Petr Malon ˇ 1 1 Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Fleming sq. 2, 166 10 Prague 6, Czech Republic 2 Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Prague 2, Czech Republic 3 Charles University in Prague, 1st Faculty of Medicine, Institute of Medical Biochemistry, Albertov 4, 128 00 Prague 2, Czech Republic 4 Spyder Institut Praha s. r. o., Nad Safinou II c. 365, Vestec, 252 42 Jesenice u Prahy, Czech Republic 5 Institute of Chemical Technology Prague, Department of Physics, Technicka ´ 190, 166 28 Prague 6, Czech Republic Received 24 February 2012; revised 1 June 2012; accepted 9 June 2012 Published online 21 June 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/bip.22105 This article was originally published online as an accepted preprint. The ‘‘Published Online’’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley. com INTRODUCTION N eurohypophyseal hormones (NHHs) are among the longest recognized biologically active peptides. Oxy- tocin (OT) and arginine vasopressin (AVP—human hormone) are structurally related nonapeptides, synthesized in hypothalamic neurons, stored in the posterior pituitary gland (neurohypophysis, NH), and released into the circulation as NHHs with very different physiological roles (Gimpl and Fahrenholz 1 ). The primary physiological role of OT is milk ejection and contraction of the uterus, whereas AVP is involved in regulation of cardio- vascular functions and acts as a hormone with antidiuretic Electronic and Vibrational Optical Activity of Several Peptides Related to Neurohypophyseal Hormones: Disulfide Group Conformation Additional Supporting Information may be found in the online version of this article. Correspondence to: Marke ´ta Pazderkova ´; e-mail: pazderkova@karlov.mff.cuni.cz ABSTRACT: Electronic and vibrational optical activity of the set of neurohypophyseal hormones and their analogs was investigated to clarify the SS bond solution conformation. The selected compounds include oxytocin (I), lysine vasopressin (II), arginine vasopressin (III), and their analogs (IV–IX), differing widely in their pharmacological properties. We have extended the already known electronic circular dichroism data by new information provided by vibrational circular dichroism (VCD) and Raman optical activity (ROA). The use of VCD brought additional details on three-dimensional structure of the chain reversal in the ring moiety and on its left handedness. Furthermore, Raman scattering and ROA allowed us to deduce the sense of the disulfide bond torsion. # 2012 Wiley Periodicals, Inc. Biopolymers 97: 923–932, 2012. Keywords: neurohypophyseal hormones; disulfide bridge; chiroptical spectroscopy; circular dichroism; Raman optical activity; vibrational circular dichroism; oxytocin; vasopressin; analogs; conformation Contract grant sponsor: Grant Agency of the Czech Republic (project no. P205/10/ 1276) Contract grant sponsor: Grant Agency of Charles University (project no. 578212) Contract grant sponsor: Ministry of Education, Youth and Sports (MSM 0021620806) V V C 2012 Wiley Periodicals, Inc. Biopolymers Volume 97 / Number 11 923