In this short communication, we report on three striking phenomena of the circadian rhythm. One was observed with the non-linear concentration changes of the monomeric L-Cys and the non-linear yields of the L-Cys derived peptides, when undergoing spontaneous non-linear peptidization. The other one was observed with the binary L-Phe-L-Pro system, and the third one with L-Ser, D-Ser, and DL-Ser. So far, no analogous reports have been released on the circadian rhythm of the spontaneous non-linear peptidization of proteinogenic amino acids in a sterile abiotic environment (70% aqueous acetonitrile, or 70% aqueous methanol solutions). At the moment, we cannot find any rational explanation of this phenomenon, yet it seems highly probable that its origin is analogous to or even of a primordial nature for the circadian rhythm phenomena abundantly found in biological samples by other researchers. An experimentally established lack of the circadian rhythm with peptidization of the non-proteinogenic amino acid (DSer) can encourage us to revisit a still unsolved question of homochirality preconditions

Godziek, Agnieszka

Kowalska, Teresa

Maciejowska, Anna

Sajewicz, Mieczysław

Acta Chromatographica

English

A. Maciejowska

A. Godziek

M. Sajewicz

T. Kowalska

Crossref

Circadian rhythm of spontaneous non-linear peptidization with proteinogenic amino acids in abiotic solutions <i>versus</i> homochirality

Repozytorium Uniwersytetu Śląskiego RE-BUŚ

             Title: Circadian rhythm of spontaneous non-linear peptidization with proteinogenic amino acids in abiotic solutions versus homochirality  Author: Anna Maciejowska, Agnieszka Godziek, Mieczysław Sajewicz, Teresa Kowalska  Citation style: Maciejowska Anna, Godziek Agnieszka, Sajewicz Mieczysław, Kowalska Teresa. (2017). Circadian rhythm of spontaneous non-linear peptidization with proteinogenic amino acids in abiotic solutions versus homochirality. "Acta Chromatographica" (Vol. 29, iss. 1 (2017), s. 135-142), doi 10.1556/1326.2017.29.1.00 Short Communication  Acta Chromatographica 29(2017)1, 135–142 DOI: 10.1556/1326.2017.29.1.00  This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium for non-commercial purposes, provided the original author and source are credited. First published online: October 21, 2015  ISSN 2083-5736 © The Author(s) Circadian Rhythm of Spontaneous non-Linear Peptidization with Proteinogenic Amino Acids in Abiotic Solutions versus Homochirality  A. MACIEJOWSKA, A. GODZIEK, M. SAJEWICZ and T. KOWALSKA*  Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice, Poland *E-mail: teresa.kowalska@us.edu.pl   Summary. In this short communication, we report on three striking phenomena of the circadian rhythm. One was observed with the non-linear concentration changes of the monomeric L-Cys and the non-linear yields of the L-Cys derived peptides, when under-going spontaneous non-linear peptidization. The other one was observed with the bina-ry L-Phe-L-Pro system, and the third one with L-Ser, D-Ser, and DL-Ser. So far, no analo-gous reports have been released on the circadian rhythm of the spontaneous non-linear peptidization of proteinogenic amino acids in a sterile abiotic environment (70% aqueous acetonitrile, or 70% aqueous methanol solutions). At the moment, we cannot find any ra-tional explanation of this phenomenon, yet it seems highly probable that its origin is analogous to or even of a primordial nature for the circadian rhythm phenomena abun-dantly found in biological samples by other researchers. An experimentally established lack of the circadian rhythm with peptidization of the non-proteinogenic amino acid (D-Ser) can encourage us to revisit a still unsolved question of homochirality preconditions.  Key Words: circadian rhythm, proteinogenic amino acids, spontaneous non-linear pep-tidization, HPLC-ELSD, turbidimetry, homochirality precondition   Experiment  Spontaneous non-linear peptidization of proteinogenic amino acids dis-solved in aqueous organic solvents was demonstrated in our earlier reports (e.g., [1–5]), and possible molecular mechanism of this process was also dis-cussed. These investigations were carried out for the solutions containing single amino acids and the amino acid pairs. In paper [5], a theoretical mod-el was proposed assuming four possible cases of spontaneous peptidization in solutions containing a pair of amino acids. The main analytical tool employed in the aforementioned papers to trace spontaneous non-linear changes of the amino acid concentration in the course of sample storage (and ageing) was high-performance liquid chro-A. Maciejowska et al.  136matography with evaporative light scattering detection (HPLC–ELSD). With its aid, the monomeric amino acid fraction can be separated from the spontaneously formed peptides and the time series of the changing peak heights valid for the monomeric amino acid witnesses to its non-linear con-centration changes in the course of storage. These changes provide an indi-rect hint as to the non-linear changes of the resulting peptide yields also. Di-rect evidence of the non-linear changes of peptide yields can be obtained with aid of turbidimetric measurements in continuous mode. Such meas-urements can reveal non-linear turbidity changes of the amino acid solution (unequivocal with the changing peptide yields) right from the moment of the amino acid dissolution and long before the insoluble higher peptides precipitate, which then can be traced with human eye. Currently, we intend to focus on our results mostly published else-where, yet without earlier pointing out to one of the most striking features of the spontaneous non-linear peptidization of the proteinogenic amino ac-ids, and namely on the circadian rhythm of this process, revealed both with aid of HPLC-ELSD and turbidimetry. First example demonstrates the circadian rhythm of the non-linear con-centration and the yield changes with the monomeric L-Cys and the L-Cys-derived peptides, respectively, as traced in the course of the 4 days lasting L-Cys solution storage. Details concerning the experimental conditions are given elsewhere [6] and here, let us only emphasize that the investigated samples were protected from the day-night light changes (both in the au-tosampler of the chromatograph and the turbidimetric cell). Moreover, the chromatographic column of the C18 type used for the HPLC-ELSD experi-ments was thermostatted at 35°C, and turbidimeter was put in a foamed polystyrene box to preserve constant temperature throughout an entire ex-periment (22±0.5°C). Last not least, the L-Cys sample was prepared in the aseptic 70% aqueous acetonitrile. The results obtained are shown in Fig 1(a),(b). Above each of the two plots, roughly estimated periods of the plot shape repetitions are given. In the case of the concentration changes with the monomeric L-Cys, these periods range from 23.75 to 24.95 h, and the analogous repetition periods on the plot of the peptide yield changes range from 21.60 to 25.20 h. Taking into account the physical difference between the monomeric L-Cys concentration and an overall turbidity of the peptides containing L-Cys solution, and the difference in accuracy of the chromato-graphic and turbidimetric measurements, there is no doubt that the two re-sult sets given in Fig. 1(a),(b) unequivocally witness to the circadian rhythm of the L-Cys peptidization. Circadian Rhythm of Spontaneous non-Linear Peptidization  137  Fig. 1. (a) The chromatographic peak height changes of the monomeric L-Cys and (b) the turbidity changes for the L-Cys solution in 70% aqueous acetonitrile in the initial 4 days of the sample storage. Concentration of L-Cys was equal to 0.7 mg mL–1  (5.77 × 10-3 mol L–1). Duration of the plot shape repetition periods (∆t, [h]) is marked above the respective plots A. Maciejowska et al.  138Second example demonstrates the circadian rhythm of the non-linear con-centration changes with L-Phe and L-Pro in the binary L-Phe-L-Pro system, and the circadian rhythm of the turbidity changes in the same system, as traced in the course of the 11 days lasting sample storage. The HPLC-ELSD re-sults valid for second example were originally presented in paper [3].  The L-Phe-L-Pro sample was also dissolved in 70% aqueous acetonitrile, and it was protected from the day-night light changes in the autosampler of the chromatograph and the turbidimetric cell, respectively. The chromato-graphic column of the C18 type was thermostatted at 35° and the turbidime-ter temperature was kept steady in the previously described way (22±0.5°C). The results obtained are shown in Fig. 2(a),(b). Periodicity of the plot shape repetitions (HPLC-ELSD) valid for L-Phe and L-Pro ranges from 18.23 to 25.67 h, yet in most cases the repeatability periods are closer to each other and range from 20.40 to 23.51 h (Fig. 2(a)). Even more regular is the shape of the registered turbidity plot (Fig. 2(b)) and in this case, the plot repeatability periods hold between 19.66 and 26.80 h. Thus it can be stated that sponta-neous peptidization of L-Phe and L-Pro in the binary L-Phe-L-Pro system proceeds in the circadian rhythm.  (a)   Fig. 2. (a) The chromatographic peak height changes of the monomeric L-Phe and L-Pro in the binary L-Phe-L-Pro solution in 70% aqueous acetonitrile and (b) the turbidity changes for the L-Phe-L-Pro solution in 70% aqueous acetonitrile in the initial 11 days of sample storage. Concentration of L-Phe and L-Pro was equal to 1.0 and 1.0 mg mL–1 (6.05 × 10-3 and 8.69 × 10-3 mol L–1), respectively. Duration of the plot shape repetition periods (∆t, [h]) is marked above the respective plots   Circadian Rhythm of Spontaneous non-Linear Peptidization  139(b)  Fig. 2. Cont.   The turbidimetric results of the third experiment are presented for the first time now and they refer to L-Ser (proteinogenic amino acid), D-Ser (non-proteinogenic amino acid), and DL-Ser (the racemic mixture of the Ser enantiomers) dissolved in a strongly antiseptic 70% aqueous methanol. These results were recorded in the course of the 7 days sample storage peri-od and similar to the two aforementioned examples, also in this case the turbidimeter was kept at constant temperature (22±0.5oC) throughout an en-tire experiment. The results obtained are given in Fig. 3(a)–(c). Based on the plot presented in Fig. 3a and valid for L-Ser, it can be stated that although the plot shape repetition periods differ from 19.66 to 32.63 h, most of them range from 21.12 to 25.20 h, which well corresponds with the circadian rhythm. In the case of D-Ser (which is a non-proteinogenic amino acid), no circadian peptidization rhythm is observed and sample turbidity is monot-onously growing (in pace with the growing peptide yields), except for one maximum after ca. 2 days storage period (Fig. 3(b)). In the case of DL-Ser, ir-regular repetitions of the plot shape pattern are observed, apparently as a kind of a ‘compromise’ between the regularity of the L-Ser pattern and no plot shape repetitions with D-Ser (Fig. 3(c)). The most amazing outcome of this experiment is that the circadian peptidization rhythm holds for the pro-teinogenic L-Ser only, whereas no such rhythm is observed with the non-proteinogenic D-Ser. Thus a supposal can be formulated that maybe the necessary precondition for the homochirality of amino acids in human and A. Maciejowska et al.  140animal tissues is founded on the circadian rhythm of the proteinogenic amino acids involved, although a tedious and thorough experimental con-firmation of this supposal is inevitable.  Fig. 3. The turbidity changes for the L-Ser, D-Ser, and DL-Ser solution in 70% aqueous methanol in the initial 7 days of sample storage. Concentration of L-Ser, D-Ser, and  DL-Ser was equal to 1.0 mg mL–1 (9.44 × 10–3 mol L–1). Duration of the plot shape repetition periods (∆t, [h]) valid for L-Ser is marked above the plot of L-Ser   Finally, it has to be added that the turbidimetric measurements were performed for all solvents used in our experiments (water, acetronitrile, methanol, 70% aqueous acetonitile, and 70% aqueous methanol), and stabil-ity of the turbidity levels was confirmed with each tested solvent system. Circadian Rhythm of Spontaneous non-Linear Peptidization  141Discussion  The circadian rhythm of the peptide concentration changes and the other physiological phenomena has been revealed by many researchers in biolog-ical material, and investigated both under the in vivo and in vitro conditions (e.g., [8–13]). Up to our best knowledge, this is the first report in the litera-ture on the circadian rhythm of the non-linear concentration changes with the monomeric amino acids and the resulting peptides, carried out in full abstraction from any biological matter, and with use of the commercially obtained amino acids of analytical purity and the HPLC purity grade sol-vents only.  Conclusion  We cannot offer any rational explanation of the circadian rhythm observed with four proteinogenic amino acids discussed in this study (and not taking place with one non-proteinogenic amino acid). It can only be speculated that the proteinogenic amino acids formed in the evolutionary course of bi-ogenesis characterize with physicochemical properties (like, e.g., the pKa values, the dipole moments, the electric permeabilities, etc.) which in some way promote this circadian rhythm. Moreover, it seems probable that the circadian rhythm of spontaneous non-linear peptidization observed with proteinogenic amino acids is of a primordial nature and the same mecha-nism is responsible for the circadian rhythms widely observed with biologi-cal matter. In other words, maybe the proteinogenic amino acids act as trig-gers of the circadian clocks abundantly observed in Nature. Last not least, an observation of the circadian peptidization rhythm with L-Ser and no such effect with D-Ser naturally reminds us of the so far unknown sources of homochirality. In future experiments, the dynamics of spontaneous pep-tidization with D-isomers of proteinogenic amino acids should be tested to find out if the circadian peptidization rhythm occurs with the proteinogenic L-amino acids only.   References  [1] M. Sajewicz, M. Matlengiewicz, M. Leda, M. Gontarska, D. Kronenbach, T. Kow-alska, and I.R. Epstein, J. Phys. Org. Chem., 23, 1066–1073 (2010) [2] M. Sajewicz, M. Gontarska, D. Kronenbach, M. Leda, T. Kowalska, and I.R. Epstein, J. Syst. Chem., 1:7 (2010); DOI:10.1186/1759-2208-1-7 A. Maciejowska et al.  142[3] M. Sajewicz, A. Godziek, A. Maciejowska, and T. Kowalska, J. Chromatogr. Sci., 53, 31–37 (2015) [4] A. Godziek, A. Maciejowska, M. Sajewicz, and T. Kowalska, J. Chromatogr. Sci., 53, 401–410 (2015) [5] M. Sajewicz, M. Dolnik, T. Kowalska, and I.R. Epstein, RSC Advances, 4, 7330–7339 (2014) [6] A. Maciejowska, A. Godziek, E. Talik, M. Sajewicz, T. Kowalska and I.R. Epstein, paper in preparation [7] A. Godziek, A. Maciejowska, E. Talik, R. Wrzalik, M. Sajewicz, and T. Kowalska, Curry. Protein Pept. Sci. (accepted) [8] M. Nakajima, K. Imai, H. Ito, T. Nishiwaki, Y. Murayama, H. Iwasaki, T. Oyama, and T. Kondo, Science, 308, 414–415 (2005) [9] J.L. Ditty, S.B. Williams, and S.S. Golden, Annu. Rev. Genet. 37, 513–543 (2003) [10] C.H. Johnson, Curr. Issues Mol. Biol. 6, 103–110 (2004) [11] C.H. Johnson and M. Egli, Nat. Struct. Mol. Biol. 11, 584–585 (2004) [12] D. Staiger, J. Shin, M. Johansson, and S.J Davis, Genome Biol., 14, 208 (2013) [13] K.M. Vaze and V.K. Sharma, Chronobiol. Intern., 30, 413–433 (2013)   

Circadian rhythm of spontaneous non-linear peptidization with proteinogenic amino acids in abiotic solutions versus homochirality

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Circadian rhythm of spontaneous non-linear peptidization with proteinogenic amino acids in abiotic solutions versus homochirality

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