@article { ISI:000263320900032, title = {Sequence-specific unusual (1 -> 2)-type helical turns in alpha/beta-hybrid peptides}, journal = {Journal of the American Chemical Society}, volume = {130}, number = {52}, year = {2008}, month = {DEC}, pages = {17743-17754}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

This article describes novel conformationally ordered (alpha/beta-hybrid peptides consisting of repeating L-proline-anthranilic acid building blocks. These oligomers adopt a compact, right-handed helical architecture determined by the intrinsic conformational preferences of the individual amino acid residues. The striking feature of these oligomers is their ability to display an unusual periodic pseudo beta-turn network of nine-membered hydrogen-bonded rings formed in the forward direction of the sequence by 1{\textendash}\>2 amino acid interactions both in solid-state and in solution. Conformational investigations of several of these oligomers by single-crystal X-ray diffraction, solution-state NMR, and ab initio MO theory suggest that the characteristic steric and dihedral angle restraints exerted by proline are essential for stabilizing the unusual pseudo beta-turn network found in these oligomers. Replacing proline by the conformationally flexible analogue alanine (Ala) or by the conformationally more constrained alpha-amino isobutyric acid (Aib) had an adverse effect on the stabilization of this structural architecture. These findings increase the potential to design novel secondary structure elements profiting from the steric and dihedral angle constraints of the amino acid constituents and help to augment the conformational space available for synthetic oligomer design with diverse backbone structures.

}, issn = {0002-7863}, doi = {10.1021/ja804297f}, author = {Prabhakaran, Panchami and Kale, Sangram S. and Puranik, Vedavati G. and Rajamohanan, P. R. and Chetina, Olga and Howard, Judith A. K. and Hofmann, Hans-Joerg and Sanjayan, Gangadhar J.} } @article { ISI:000295890100006, title = {Bicyclic amino acid-carbohydrate-conjugates as conformationally restricted hydroxyethylamine (HEA) transition-state isosteres}, journal = {Organic \& Biomolecular Chemistry}, volume = {9}, number = {21}, year = {2011}, month = {SEP}, pages = {7300-7302}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

This communication describes a general synthetic route to bicyclic amino acid-carbohydrate-conjugates, which would be useful as conformationally restricted hydroxyethylamine (HEA) transition-state isosteres. The synthesis was achieved in 12 steps starting from D-glucose. The striking features of this system are the bicyclic rigid core displaying an a-amino acid side chain and hydroxyethylamine moiety - both of which would be potentially important for receptor interactions, leading to various biomedical responses, as described in the literature. Crystal structure investigation suggested extensive intermolecular hydrogen-bonding interactions in this system, involving the backbone amide and hydroxyl groups.

}, issn = {1477-0520}, doi = {10.1039/c1ob06215h}, author = {Kale, Sangram S. and Chavan, Sanjay T. and Sabharwal, Sushma G. and Puranik, Vedavati G. and Sanjayan, Gangadhar J.} } @article { ISI:000310215400007, title = {Conformational modulation of Ant-Pro oligomers using chirality alteration of proline residues}, journal = {Organic \& Biomolecular Chemistry}, volume = {10}, number = {42}, year = {2012}, month = {SEP}, pages = {8426-8433}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Structural modulation of Ant-Pro (anthranilic acid-proline) oligomers has been carried out by chirality alteration of the proline residues. The results suggest that the chirality altered oligomers show well-defined helical conformation featuring nine-membered hydrogen bonding interactions - without compromising conformational rigidity.

}, issn = {1477-0520}, doi = {10.1039/c2ob26132d}, author = {Kale, Sangram S. and Kotmale, Amol S. and Dutta, Achintya Kumar and Pal, Sourav and Rajamohanan, P. R. and Sanjayan, Gangadhar J.} } @article { ISI:000320036300013, title = {Ant-pro reverse-turn motif. structural features and conformational characteristics}, journal = {European Journal of Organic Chemistry}, number = {17, SI}, year = {2013}, month = {JUN}, pages = {3529-3542}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

This article details the characteristic conformational features of the Ant-Pro reverse turn ? a folded pseudo -turn motif that displays a closed nine-membered-ring hydrogen-bonded network involving just two amino acid residues, namely anthranilic acid (Ant; a constrained -amino acid), and proline (Pro; a constrained -amino acid). The results from the extensive investigation of ten crystal structures and their NMR conformations in the solution state provide a clear idea about the conformational characteristics of the Ant-Pro reverse turn. The Ant and Pro residues, which form the turn segment, maintain a perfect antiperiplanar orientation throughout, leaving little possibility for the formation of the otherwise possible six-membered hydrogen-bonding that requires a coplanar disposition of the two amino acid residues, as clearly evident from investigation of several crystal structures. The closed hydrogen-bonded network observed in the Ant-Pro reverse turn motif, formed in the forward direction of the sequence (12 amino acid interactions) involving only two amino acid residues, is in stark contrast to the native -turns that involve four residues to form hydrogen-bonded network featuring backward 14 amino acid interactions. The readily available two-residue Ant-Pro motif raises the possibility of a practical utility, particularly in the application of rigidifying flexible peptide backbones by inserting the robust Ant-Pro reverse turn motifs into their backbone.

}, keywords = {Peptides, Peptidomimetics, Protein folding, Protein structures}, issn = {1434-193X}, doi = {10.1002/ejoc.201201739}, author = {Thorat, Vijaykumar H. and Ingole, Tukaram S. and Vijayadas, Kuruppanthara N. and Nair, Roshna V. and Kale, Sangram S. and Ramesh, Veera V. E. and Davis, Hilda C. and Prabhakaran, Panchami and Gonnade, Rajesh G. and Gawade, Rupesh L. and Puranik, Vedavati G. and Rajamohanan, Pattuparambil R. and Sanjayan, Gangadhar J.} } @article { ISI:000317327900022, title = {Carboxamide versus sulfonamide in peptide backbone folding: a case study with a hetero foldamer}, journal = {Organic Letters}, volume = {15}, number = {7}, year = {2013}, month = {APR}, pages = {1504-1507}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Strikingly dissimilar hydrogen-bonding patterns have been observed for two sets of closely similar hetero foldamers containing carboxamide and sulfonamides at regular intervals. Although both foldamers maintain conformational ordering, the hydrogen-bonding pattern and backbone helical handedness differ diametrically.

}, issn = {1523-7060}, doi = {10.1021/ol4002762}, author = {Ramesh, Veera V. E. and Kale, Sangram S. and Kotmale, Amol S. and Gawade, Rupesh L. and Puranik, Vedavati G. and Rajamohanan, P. R. and Sanjayan, Gangadhar J.} } @article { ISI:000315168800015, title = {Orthanilic acid-promoted reverse turn formation in peptides}, journal = {Chemical Communications}, volume = {49}, number = {22}, year = {2013}, month = {JAN}, pages = {2222-2224}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Orthanilic acid (2-aminobenzenesulfonic acid, (S)Ant), an aromatic beta-amino acid, has been shown to be highly useful in inducing a folded conformation in peptides. When incorporated into peptide sequences (Xaa-(S)Ant-Yaa), this rigid aromatic beta-amino acid strongly imparts a reverse-turn conformation to the peptide backbone, featuring robust 11-membered-ring hydrogen-bonding.

}, issn = {1359-7345}, doi = {10.1039/c3cc40522b}, author = {Kale, Sangram S. and Priya, Gowri and Kotmale, Amol S. and Gawade, Rupesh L. and Puranik, Vedavati G. and Rajamohanan, P. R. and Sanjayan, Gangadhar J.} } @article { ISI:000331895900018, title = {Conformational modulation of peptide secondary structures using beta-aminobenzenesulfonic acid}, journal = {Chemical Communications}, volume = {50}, number = {22}, year = {2014}, month = {JAN}, pages = {2886-2888}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

This communication describes the influence of beta-aminobenzenesulfonic acid ((S)Ant) on the conformational preferences of hetero foldamers. The designed (Aib-(S)Ant-Aib)(n) and (Aib-(S)Ant-Pro)(n) oligomers display a well-defined folded conformation featuring intramolecular mixed hydrogen bonding (7/11) and intra-residual (6/5) H-bonding interactions, respectively.

}, issn = {1359-7345}, doi = {10.1039/c3cc48850k}, author = {Kale, Sangram S. and Kunjir, Shrikant M. and Gawade, Rupesh L. and Puranik, Vedavati G. and Rajamohanan, P. R. and Sanjayan, Gangadhar J.} } @article { ISI:000353205000033, title = {Novel hybrid nocodazole analogues as tubulin polymerization inhibitors and their antiproliferative activity}, journal = {Bioorganic \& Medicinal Chemistry Letters}, volume = {25}, number = {9}, year = {2015}, month = {MAY}, pages = {1982-1985}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

We describe the design, synthesis and SAR profiling of a series of novel combretastatin-nocodazole conjugates as potential anticancer agents. The thiophene ring in the nocodazole moiety was replaced by a substituted phenyl ring from the combretastatin moiety to design novel hybrid analogues. The hydroxyl group at the ortho position in compounds 2, 3 and 4 was used as the conformationally locking tool by anticipated six-membered hydrogen bonding. The bioactivity profiles of all compounds as tubulin polymerization inhibitors and as antiproliferative agents against the A-549 human lung cancer cell line were investigated Compounds 1 and 4 showed mu M IC50 values in both assays. (C) 2015 Elsevier Ltd. All rights reserved.

}, keywords = {Anticancer, Colchicine, Nocodazole, Tubulin binding}, issn = {0960-894X}, doi = {10.1016/j.bmcl.2015.03.019}, author = {Kale, Sangram S. and Jedhe, Ganesh S. and Meshram, Sachin N. and Santra, Manas K. and Hamel, Ernest and Sanjayan, Gangadhar J.} } @article { ISI:000382122200014, title = {Self-assembled vesicles of urea-tethered foldamers as hydrophobic drug carriers}, journal = {Chemical Communications}, volume = {52}, number = {71}, year = {2016}, month = {AUG}, pages = {10771-10774}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Molecular self-assembly of nonamphiphilic alpha,beta-hybrid foldamers based on urea-tethered anthranilic acid-proline (Ant-Pro) foldamers is reported. These self-assembled hollow vesicular architectures can take up and release the anticancer hydrophobic drug curcumin.

}, issn = {1359-7345}, doi = {10.1039/c6cc05079d}, author = {Ingole, Tukaram S. and Kale, Sangram S. and Sukumaran, Santhosh Babu and Sanjayan, Gangadhar J.} }