Cyclic dinucleotides (CDNs) are second messengers that activate stimulator of interferon genes (STING). The cGAS-STING pathway plays a promising role in cancer immunotherapy. Here, we describe the synthesis of CDNs containing 7-substituted 7-deazapurine moiety. We used mouse cyclic GMP-AMP synthase and bacterial dinucleotide synthases for the enzymatic synthesis of CDNs. Alternatively, 7-(het)aryl 7-deazapurine CDNs were prepared by Suzuki-Miyaura cross-couplings. New CDNs were tested in biochemical and cell-based assays for their affinity to human STING. Eight CDNs showed better activity than 2'3'-cGAMP, the natural ligand of STING. The effect on cytokine and chemokine induction was also evaluated. The best activities were observed for CDNs bearing large aromatic substituents that point above the CDN molecule. We solved four X-ray structures of complexes of new CDNs with human STING. We observed π-π stacking interactions between the aromatic substituents and Tyr240 that are involved in the stabilization of CDN-STING complexes.

1st Faculty of Medicine Charles University Katerinska 1660 32 Prague 121 08 Czech Republic

Department of Biochemistry Faculty of Science Charles University Hlavova 2030 8 Prague 128 00 Czech Republic

Department of Cell Biology Faculty of Science Charles University Vinicna 1594 7 Prague 128 43 Czech Republic

Department of Organic Chemistry Faculty of Chemical Technology University of Chemistry and Technology Technicka 5 Prague 166 28 Czech Republic

Department of Organic Chemistry Faculty of Science Charles University Hlavova 2030 8 Prague 128 00 Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo Namesti 542 Prague 166 10 Czech Republic

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Ishikawa H.; Barber G. N. STING is an endoplasmic reticulum adaptor that facilitates innate immune signalling. Nature 2008, 455, 674–678. 10.1038/nature07317. PubMed DOI PMC

Zhong B.; Yang Y.; Li S.; Wang Y.-Y.; Li Y.; Diao F.; Lei C.; He X.; Zhang L.; Tien P.; Shu H.-B. The adaptor protein MITA links virus-sensing receptors to IRF3 transcription factor activation. Immunity 2008, 29, 538–550. 10.1016/j.immuni.2008.09.003. PubMed DOI

Sun L.; Wu J.; Du F.; Chen X.; Chen Z. J. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science 2013, 339, 786–791. 10.1126/science.1232458. PubMed DOI PMC

Wu J.; Sun L.; Chen X.; Du F.; Shi H.; Chen C.; Chen Z. J. Cyclic GMP-AMP is an endogenous second messenger in innate immune signaling by cytosolic DNA. Science 2013, 339, 826–830. 10.1126/science.1229963. PubMed DOI PMC

Zhang X.; Shi H.; Wu J.; Zhang X.; Sun L.; Chen C.; Chen Z. J. Cyclic GMP-AMP containing mixed phosphodiester linkages is an endogenous high-affinity ligand for STING. Mol. Cell 2013, 51, 226–235. 10.1016/j.molcel.2013.05.022. PubMed DOI PMC

Ablasser A.; Goldeck M.; Cavlar T.; Deimling T.; Witte G.; Röhl I.; Hopfner K.-P.; Ludwig J.; Hornung V. cGAS produces a 2′-5′-linked cyclic dinucleotide second messenger that activates STING. Nature 2013, 498, 380–384. 10.1038/nature12306. PubMed DOI PMC

Ouyang S.; Song X.; Wang Y.; Ru H.; Shaw N.; Jiang Y.; Niu F.; Zhu Y.; Qiu W.; Parvatiyar K.; Li Y.; Zhang R.; Cheng G.; Liu Z.-J. Structural analysis of the STING adaptor protein reveals a hydrophobic dimer interface and mode of cyclic di-GMP binding. Immunity 2012, 36, 1073–1086. 10.1016/j.immuni.2012.03.019. PubMed DOI PMC

Krasteva P. V.; Sondermann H. Versatile modes of cellular regulation via cyclic dinucleotides. Nat. Chem. Biol. 2017, 13, 350–359. 10.1038/nchembio.2337. PubMed DOI PMC

Burdette D. L.; Monroe K. M.; Sotelo-Troha K.; Iwig J. S.; Eckert B.; Hyodo M.; Hayakawa Y.; Vance R. E. STING is a direct innate immune sensor of cyclic di-GMP. Nature 2011, 478, 515–518. 10.1038/nature10429. PubMed DOI PMC

Barker J. R.; Koestler B. J.; Carpenter V. K.; Burdette D. L.; Waters C. M.; Vance R. E.; Valdivia R. H. STING-dependent recognition of cyclic di-AMP mediates type I interferon responses during Chlamydia trachomatis infection. mBio 2013, 4, e0001810.1128/mBio.00018-13. PubMed DOI PMC

Keating S. E.; Baran M.; Bowie A. G. Cytosolic DNA sensors regulating type I interferon induction. Trends Immunol. 2011, 32, 574–581. 10.1016/j.it.2011.08.004. PubMed DOI

Liu S.; Cai X.; Wu J.; Cong Q.; Chen X.; Li T.; Du F.; Ren J.; Wu Y.-T.; Grishin N. V.; Chen Z. J. Phosphorylation of innate immune adaptor proteins MAVS, STING, and TRIF induces IRF3 activation. Science 2015, 347, aaa2630.10.1126/science.aaa2630. PubMed DOI

Shang G.; Zhang C.; Chen Z. J.; Bai X.-c.; Zhang X. Cryo-EM structures of STING reveal its mechanism of activation by cyclic GMP-AMP. Nature 2019, 567, 389–393. 10.1038/s41586-019-0998-5. PubMed DOI PMC

Zhang C.; Shang G.; Gui X.; Zhang X.; Bai X.-c.; Chen Z. J. Structural basis of STING binding with and phosphorylation by TBK1. Nature 2019, 567, 394–398. 10.1038/s41586-019-1000-2. PubMed DOI PMC

Zhao B.; Du F.; Xu P.; Shu C.; Sankaran B.; Bell S. L.; Liu M.; Lei Y.; Gao X.; Fu X.; Zhu F.; Liu Y.; Laganowsky A.; Zheng X.; Ji J.-Y.; West A. P.; Watson R. O.; Li P. A conserved PLPLRT/SD motif of STING mediates the recruitment and activation of TBK1. Nature 2019, 569, 718–722. 10.1038/s41586-019-1228-x. PubMed DOI PMC

Musella M.; Manic G.; De Maria R.; Vitale I.; Sistigu A. Type-I-interferons in infection and cancer: Unanticipated dynamics with therapeutic implications. OncoImmunology 2017, 6, e131442410.1080/2162402x.2017.1314424. PubMed DOI PMC

Barber G. N. STING: infection, inflammation and cancer. Nat. Rev. Immunol. 2015, 15, 760–770. 10.1038/nri3921. PubMed DOI PMC

Kumar V. A. A STING to inflammation and autoimmunity. J. Leukocyte Biol. 2019, 106, 171–185. 10.1002/jlb.4mir1018-397rr. PubMed DOI

Gao D.; Li T.; Li X.-D.; Chen X.; Li Q.-Z.; Wight-Carter M.; Chen Z. J. Activation of cyclic GMP-AMP synthase by self-DNA causes autoimmune diseases. Proc. Natl. Acad. Sci. U.S.A. 2015, 112, E569910.1073/pnas.1516465112. PubMed DOI PMC

Novotná B.; Vaneková L.; Zavřel M.; Buděšínský M.; Dejmek M.; Smola M.; Gutten O.; Tehrani Z. A.; Pimková Polidarová M.; Brázdová A.; Liboska R.; Štěpánek I.; Vavřina Z.; Jandušík T.; Nencka R.; Rulíšek L.; Bouřa E.; Brynda J.; Páv O.; Birkuš G. Enzymatic preparation of 2′–5′,3′–5′-cyclic dinucleotides, their binding properties to stimulator of interferon genes adaptor protein, and structure/activity correlations. J. Med. Chem. 2019, 62, 10676–10690. 10.1021/acs.jmedchem.9b01062. PubMed DOI

Zhang H.; You Q.-D.; Xu X.-L. Targeting stimulator of interferon genes (STING): A medicinal chemistry perspective. J. Med. Chem. 2020, 63, 3785–3816. 10.1021/acs.jmedchem.9b01039. PubMed DOI

Le Naour J.; Zitvogel L.; Galluzzi L.; Vacchelli E.; Kroemer G. Trial watch: STING agonists in cancer therapy. OncoImmunology 2020, 9, 1777624.10.1080/2162402x.2020.1777624. PubMed DOI PMC

Fu J.; Kanne D. B.; Leong M.; Glickman L. H.; McWhirter S. M.; Lemmens E.; Mechette K.; Leong J. J.; Lauer P.; Liu W.; Sivick K. E.; Zeng Q.; Soares K. C.; Zheng L.; Portnoy D. A.; Woodward J. J.; Pardoll D. M.; Dubensky T. W.; Kim Y. STING agonist formulated cancer vaccines can cure established tumors resistant to PD-1 blockade. Sci. Transl. Med. 2015, 7, 283ra52.10.1126/scitranslmed.aaa4306. PubMed DOI PMC

Chang W.; Altman M. D.; Lesburg C. A.; Perera S. A.; Piesvaux J. A.; Schroeder G. K.; Wyss D. F.; Cemerski S.; Chen Y.; DiNunzio E.; Haidle A. M.; Ho T.; Kariv I.; Knemeyer I.; Kopinja J. E.; Lacey B. M.; Laskey J.; Lim J.; Long B. J.; Ma Y.; Maddess M. L.; Pan B.-S.; Presland J. P.; Spooner E.; Steinhuebel D.; Truong Q.; Zhang Z.; Fu J.; Addona G. H.; Northrup A. B.; Parmee E.; Tata J. R.; Bennett D. J.; Cumming J. N.; Siu T.; Trotter B. W. Discovery of MK-1454: A potent cyclic dinucleotide stimulator of interferon genes agonist for the treatment of cancer. J. Med. Chem. 2022, 65, 5675–5689. 10.1021/acs.jmedchem.1c02197. PubMed DOI

Carideo Cunniff E.; Sato Y.; Mai D.; Appleman V. A.; Iwasaki S.; Kolev V.; Matsuda A.; Shi J.; Mochizuki M.; Yoshikawa M.; Huang J.; Shen L.; Haridas S.; Shinde V.; Gemski C.; Roberts E. R.; Ghasemi O.; Bazzazi H.; Menon S.; Traore T.; Shi P.; Thelen T. D.; Conlon J.; Abu-Yousif A. O.; Arendt C.; Shaw M. H.; Okaniwa M. TAK-676: A novel stimulator of interferon genes (STING) agonist promoting durable IFN-dependent antitumor immunity in preclinical studies. Cancer Res. Commun. 2022, 2, 489–502. 10.1158/2767-9764.crc-21-0161. PubMed DOI PMC

Vyskocil S.; Cardin D.; Ciavarri J.; Conlon J.; Cullis C.; England D.; Gershman R.; Gigstad K.; Gipson K.; Gould A.; Greenspan P.; Griffin R.; Gulavita N.; Harrison S.; Hu Z.; Hu Y.; Hata A.; Huang J.; Huang S.-C.; Janowick D.; Jones M.; Kolev V.; Langston S. P.; Lee H. M.; Li G.; Lok D.; Ma L.; Mai D.; Malley J.; Matsuda A.; Mizutani H.; Mizutani M.; Molchanova N.; Nunes E.; Pusalkar S.; Renou C.; Rowland S.; Sato Y.; Shaw M.; Shen L.; Shi Z.; Skene R.; Soucy F.; Stroud S.; Xu H.; Xu T.; Abu-Yousif A. O.; Zhang J. Identification of novel carbocyclic pyrimidine cyclic dinucleotide STING agonists for antitumor immunotherapy using systemic intravenous route. J. Med. Chem. 2021, 64, 6902–6923. 10.1021/acs.jmedchem.1c00374. PubMed DOI

Ramanjulu J. M.; Pesiridis G. S.; Yang J.; Concha N.; Singhaus R.; Zhang S.-Y.; Tran J.-L.; Moore P.; Lehmann S.; Eberl H. C.; Muelbaier M.; Schneck J. L.; Clemens J.; Adam M.; Mehlmann J.; Romano J.; Morales A.; Kang J.; Leister L.; Graybill T. L.; Charnley A. K.; Ye G.; Nevins N.; Behnia K.; Wolf A. I.; Kasparcova V.; Nurse K.; Wang L.; Puhl Y.; Li M.; Klein C. B.; Hopson J.; Guss M.; Bantscheff G.; Bergamini M. A.; Reilly Y.; Lian K. J.; Duffy J.; Adams K. P.; Foley P. J.; Gough R. W.; Marquis J.; Smothers A.; Hoos J.; Bertin J. Design of amidobenzimidazole STING receptor agonists with systemic activity. Nature 2018, 564, 439–443. 10.1038/s41586-018-0705-y. PubMed DOI

Banerjee M.; Middya S.; Shrivastava R.; Basu S.; Ghosh R.; Pryde D. C.; Yadav D. B.; Surya A. G10 is a direct activator of human STING. PLoS One 2020, 15, e023774310.1371/journal.pone.0237743. PubMed DOI PMC

Sali T. M.; Pryke K. M.; Abraham J.; Liu A.; Archer I.; Broeckel R.; Staverosky J. A.; Smith J. L.; Al-Shammari A.; Amsler L.; Sheridan K.; Nilsen A.; Streblow D. N.; DeFilippis V. R. Characterization of a novel human-specific STING agonist that elicits antiviral activity against emerging alphaviruses. PLoS Pathog. 2015, 11, e100532410.1371/journal.ppat.1005324. PubMed DOI PMC

Pan B.-S.; Perera S. A.; Piesvaux J. A.; Presland J. P.; Schroeder G. K.; Cumming J. N.; Trotter B. W.; Altman M. D.; Buevich A. V.; Cash B.; Cemerski S.; Chang W.; Chen Y.; Dandliker P. J.; Feng G.; Haidle A.; Henderson T.; Jewell J.; Kariv I.; Knemeyer I.; Kopinja J.; Lacey B. M.; Laskey J.; Lesburg C. A.; Liang R.; Long B. J.; Lu M.; Ma Y.; Minnihan E. C.; O’Donnell G.; Otte R.; Price L.; Rakhilina L.; Sauvagnat B.; Sharma S.; Tyagarajan S.; Woo H.; Wyss D. F.; Xu S.; Bennett D. J.; Addona G. H. An orally available non-nucleotide STING agonist with antitumor activity. Science 2020, 369, eaba609810.1126/science.aba6098. PubMed DOI

Cherney E. C.; Zhang L.; Lo J.; Huynh T.; Wei D.; Ahuja V.; Quesnelle C.; Schieven G. L.; Futran A.; Locke G. A.; Lin Z.; Monereau L.; Chaudhry C.; Blum J.; Li S.; Fereshteh M.; Li-Wang B.; Gangwar S.; Pan C.; Chong C.; Zhu X.; Posy S. L.; Sack J. S.; Zhang P.; Ruzanov M.; Harner M.; Akhtar F.; Schroeder G. M.; Vite G.; Fink B. Discovery of non-nucleotide small-molecule STING agonists via chemotype hybridization. J. Med. Chem. 2022, 65, 3518–3538. 10.1021/acs.jmedchem.1c01986. PubMed DOI

Jeon M. J.; Lee H.; Lee J.; Baek S. Y.; Lee D.; Jo S.; Lee J.-Y.; Kang M.; Jung H. R.; Han S. B.; Kim N.-J.; Lee S.; Kim H. Development of potent immune modulators targeting stimulator of interferon genes receptor. J. Med. Chem. 2022, 65, 5407–5432. 10.1021/acs.jmedchem.1c01795. PubMed DOI

Novotná B.; Holá L.; Staś M.; Gutten O.; Smola M.; Zavřel M.; Vavřina Z.; Buděšínský M.; Liboska R.; Chevrier F.; Dobiaš J.; Boura E.; Rulíšek L.; Birkuš G. Enzymatic synthesis of 3′–5′, 3′–5′ cyclic dinucleotides, their binding properties to the stimulator of interferon genes adaptor protein, and structure/activity correlations. Biochemistry 2021, 60, 3714–3727. 10.1021/acs.biochem.1c00692. PubMed DOI

Rosenthal K.; Becker M.; Rolf J.; Siedentop R.; Hillen M.; Nett M.; Lütz S. Catalytic Promiscuity of cGAS: A Facile Enzymatic Synthesis of 2′-3′-Linked Cyclic Dinucleotides. ChemBioChem 2020, 21, 3225–3228. 10.1002/cbic.202000433. PubMed DOI PMC

Bartsch T.; Becker M.; Rolf J.; Rosenthal K.; Lütz S. Biotechnological production of cyclic dinucleotides-Challenges and opportunities. Biotechnol. Bioeng. 2022, 119, 677–684. 10.1002/bit.28027. PubMed DOI

Schwede F.; Genieser H.-G.; Rentsch A.. The chemistry of the noncanonical cyclic dinucleotide 2′3′-cGAMP and its analogs. In Non-canonical Cyclic Nucleotides; Seifert R., Ed.; Springer International Publishing: Cham, 2017; pp 359–384. PubMed

Milisavljevic N.; Konkolová E.; Kozák J.; Hodek J.; Veselovská L.; Sýkorová V.; Čížek K.; Pohl R.; Eyer L.; Svoboda P.; Růžek D.; Weber J.; Nencka R.; Bouřa E.; Hocek M. Antiviral activity of 7-substituted 7-deazapurine ribonucleosides, monophosphate prodrugs, and triphoshates against emerging RNA viruses. ACS Infect. Dis. 2021, 7, 471–478. 10.1021/acsinfecdis.0c00829. PubMed DOI

Zhu X.-F.; Williams H. J.; Ian Scott A. An Improved Transient Method for the Synthesis ofN-Benzoylated Nucleosides. Synth. Commun. 2003, 33, 1233–1243. 10.1081/scc-120017200. DOI

Hakimelahi G. H.; Proba Z. A.; Ogilvie K. K. New catalysts and procedures for the dimethoxytritylation and selective silylation of ribonucleosides. Can. J. Chem. 1982, 60, 1106–1113. 10.1139/v82-165. DOI

Wei X. Coupling activators for the oligonucleotide synthesis via phosphoramidite approach. Tetrahedron 2013, 69, 3615–3637. 10.1016/j.tet.2013.03.001. DOI

Gaffney B. L.; Veliath E.; Zhao J.; Jones R. A. One-flask syntheses of c-di-GMP and the [Rp,Rp] and [Rp,Sp] thiophosphate analogues. Org. Lett. 2010, 12, 3269–3271. 10.1021/ol101236b. PubMed DOI PMC

Hocek M. Synthesis of base-modified 2′-deoxyribonucleoside triphosphates and their use in enzymatic synthesis of modified DNA for applications in bioanalysis and chemical biology. J. Org. Chem. 2014, 79, 9914–9921. 10.1021/jo5020799. PubMed DOI

Veliath E.; Kim S.; Gaffney B. L.; Jones R. A. Synthesis and characterization of C8 analogs of c-di-GMP. Nucleosides, Nucleotides Nucleic Acids 2011, 30, 961–978. 10.1080/15257770.2011.624567. PubMed DOI

Bourderioux A.; Nauš P.; Perlíková P.; Pohl R.; Pichová I.; Votruba I.; Džubák P.; Konečný P.; Hajdúch M.; Stray K. M.; Wang T.; Ray A. S.; Feng J. Y.; Birkus G.; Cihlar T.; Hocek M. Synthesis and significant cytostatic activity of 7-hetaryl-7-deazaadenosines. J. Med. Chem. 2011, 54, 5498–5507. 10.1021/jm2005173. PubMed DOI

Milisavljevič N.; Perlíková P.; Pohl R.; Hocek M. Enzymatic synthesis of base-modified RNA by T7 RNA polymerase. A systematic study and comparison of 5-substituted pyrimidine and 7-substituted 7-deazapurine nucleoside triphosphates as substrates. Org. Biomol. Chem. 2018, 16, 5800–5807. 10.1039/c8ob01498a. PubMed DOI

Snášel J.; Nauš P.; Dostál J.; Hnízda A.; Fanfrlík J.; Brynda J.; Bourderioux A.; Dušek M.; Dvořáková H.; Stolaříková J.; Zábranská H.; Pohl R.; Konečný P.; Džubák P.; Votruba I.; Hajdúch M.; Řezáčová P.; Veverka V.; Hocek M.; Pichová I. Structural basis for inhibition of mycobacterial and human adenosine kinase by 7-substituted 7-(het)aryl-7-deazaadenine ribonucleosides. J. Med. Chem. 2014, 57, 8268–8279. 10.1021/jm500497v. PubMed DOI

Vavřina Z.; Gutten O.; Smola M.; Zavřel M.; Aliakbar Tehrani Z.; Charvát V.; Kožíšek M.; Boura E.; Birkuš G.; Rulíšek L. Protein-Ligand Interactions in the STING Binding Site Probed by Rationally Designed Single-Point Mutations: Experiment and Theory. Biochemistry 2021, 60, 607–620. 10.1021/acs.biochem.0c00949. PubMed DOI

Smola M.; Gutten O.; Dejmek M.; Kožíšek M.; Evangelidis T.; Tehrani Z. A.; Novotná B.; Nencka R.; Birkuš G.; Rulíšek L.; Boura E. Ligand strain and its conformational complexity is a major factor in the binding of cyclic dinucleotides to STING protein. Angew. Chem., Int. Ed. Engl. 2021, 60, 10172–10178. 10.1002/anie.202016805. PubMed DOI PMC

Yi G.; Brendel V. P.; Shu C.; Li P.; Palanathan S.; Cheng Kao C. Single nucleotide polymorphisms of human STING can affect innate immune response to cyclic dinucleotides. PLoS One 2013, 8, e7784610.1371/journal.pone.0077846. PubMed DOI PMC

Dejmek M.; Šála M.; Brazdova A.; Vanekova L.; Smola M.; Klíma M.; Břehová P.; Buděšínský M.; Dračínský M.; Procházková E.; Zavřel M.; Šimák O.; Páv O.; Boura E.; Birkuš G.; Nencka R. Discovery of isonucleotidic CDNs as potent STING agonists with immunomodulatory potential. Structure 2022, 30, 1146–1156. 10.1016/j.str.2022.05.012. PubMed DOI

Shih A. Y.; Damm-Ganamet K. L.; Mirzadegan T. Dynamic Structural Differences between Human and Mouse STING Lead to Differing Sensitivity to DMXAA. Biophys. J. 2018, 114, 32–39. 10.1016/j.bpj.2017.10.027. PubMed DOI PMC

Smola M.; Birkus G.; Boura E. No magnesium is needed for binding of the stimulator of interferon genes to cyclic dinucleotides. Acta Crystallogr., Sect. F: Struct. Biol. Commun. 2019, 75, 593–598. 10.1107/s2053230x19010999. PubMed DOI PMC

Lioux T.; Mauny M.-A.; Lamoureux A.; Bascoul N.; Hays M.; Vernejoul F.; Baudru A.-S.; Boularan C.; Lopes-Vicente J.; Qushair G.; Tiraby G. Design, Synthesis, and Biological Evaluation of Novel Cyclic Adenosine-Inosine Monophosphate (cAIMP) Analogs That Activate Stimulator of Interferon Genes (STING). J. Med. Chem. 2016, 59, 10253–10267. 10.1021/acs.jmedchem.6b01300. PubMed DOI

Pimková Polidarová M.; Břehová P.; Kaiser M. M.; Smola M.; Dračínský M.; Smith J.; Marek A.; Dejmek M.; Šála M.; Gutten O.; Rulíšek L.; Novotná B.; Brázdová A.; Janeba Z.; Nencka R.; Boura E.; Páv O.; Birkuš G. Synthesis and biological evaluation of phosphoester and phosphorothioate prodrugs of STING agonist 3′,3′-c-Di(2′F,2′dAMP). J. Med. Chem. 2021, 64, 7596–7616. 10.1021/acs.jmedchem.1c00301. PubMed DOI

Seela F.; Ming X. 7-Functionalized 7-deazapurine β-d and β-l-ribonucleosides related to tubercidin and 7-deazainosine: glycosylation of pyrrolo[2,3-d]pyrimidines with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d or β-l-ribofuranose. Tetrahedron 2007, 63, 9850–9861. 10.1016/j.tet.2007.06.107. DOI

Mueller U.; Förster R.; Hellmig M.; Huschmann F. U.; Kastner A.; Malecki P.; Pühringer S.; Röwer M.; Sparta K.; Steffien M.; Ühlein M.; Wilk P.; Weiss M. S. The macromolecular crystallography beamlines at BESSY II of the Helmholtz-Zentrum Berlin: Current status and perspectives. Eur. Phys. J. Plus 2015, 130, 141.10.1140/epjp/i2015-15141-2. DOI

Kabsch W. XDS. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2010, 66, 125–132. 10.1107/s0907444909047337. PubMed DOI PMC

Vagin A.; Teplyakov A. Molecular replacement withMOLREP. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2010, 66, 22–25. 10.1107/s0907444909042589. PubMed DOI

Winn M. D.; Ballard C. C.; Cowtan K. D.; Dodson E. J.; Emsley P.; Evans P. R.; Keegan R. M.; Krissinel E. B.; Leslie A. G. W.; McCoy A.; McNicholas S. J.; Murshudov G. N.; Pannu N. S.; Potterton E. A.; Powell H. R.; Read R. J.; Vagin A.; Wilson K. S. Overview of theCCP4 suite and current developments. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2011, 67, 235–242. 10.1107/s0907444910045749. PubMed DOI PMC

Adams P. D.; Afonine P. V.; Bunkóczi G.; Chen V. B.; Davis I. W.; Echols N.; Headd J. J.; Hung L.-W.; Kapral G. J.; Grosse-Kunstleve R. W.; McCoy A. J.; Moriarty N. W.; Oeffner R.; Read R. J.; Richardson D. C.; Richardson J. S.; Terwilliger T. C.; Zwart P. H. PHENIX: a comprehensive Python-based system for macromolecular structure solution. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2010, 66, 213–221. 10.1107/s0907444909052925. PubMed DOI PMC

Debreczeni J. E.; Emsley P. Handling ligands with Coot. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2012, 68, 425–430. 10.1107/s0907444912000200. PubMed DOI PMC