1.Controlled synthesis of amino acid-based pH-responsive chiral polymers and self-assembly of their block copolymers.
Bauri K1, Roy SG, Pant S, De P. Langmuir. 2013 Feb 26;29(8):2764-74. doi: 10.1021/la304918s. Epub 2013 Feb 11.
Leucine/isoleucine side chain polymers are of interest due to their hydrophobicity and reported role in the formation of α-helical structures. The synthesis and reversible addition-fragmentation chain transfer (RAFT) polymerization of amino acid-based chiral monomers, namely Boc-L-leucine methacryloyloxyethyl ester (Boc-L-Leu-HEMA, 1a), Boc-L-leucine acryloyloxyethyl ester (Boc-L-Leu-HEA, 1b), Boc-L-isoleucine methacryloyloxyethyl ester (Boc-L-Ile-HEMA, 1c), and Boc-L-isoleucine acryloyloxyethyl ester (Boc-L-Ile-HEA, 1d), are reported. The controlled nature of the polymerization of the said chiral monomers in N, N-dimethylformamide (DMF) at 70 °C is evident from the formation of narrow polydisperse polymers, the molecular weight controlled by the monomer/chain transfer agent (CTA) molar ratio and the linear relationship between molecular weight and monomer conversion. The resulting well-defined polymers were used as macro-CTAs to prepare corresponding diblock copolymers by RAFT polymerization of methyl (meth)acrylate monomers.
2.Three-dimensional structure of carboxypeptidase T from Thermoactinomyces vulgaris in complex with N-BOC-L-leucine.
Timofeev VI1, Kuznetsov SA, Akparov VKh, Chestukhina GG, Kuranova IP. Biochemistry (Mosc). 2013 Mar;78(3):252-9. doi: 10.1134/S0006297913030061.
The 3D structure of recombinant bacterial carboxypeptidase T (CPT) in complex with N-BOC-L-leucine was determined at 1.38 Å resolution. Crystals for the X-ray study were grown in microgravity using the counter-diffusion technique. N-BOC-L-leucine and SO4(2-) ion bound in the enzyme active site were localized in the electron density map. Location of the leucine side chain in CPT-N-BOC-L-leucine complex allowed identification of the S1 subsite of the enzyme, and its structure was determined. Superposition of the structures of CPT-N-BOC-L-leucine complex and complexes of pancreatic carboxypeptidases A and B with substrate and inhibitors was carried out, and similarity of the S1 subsites in these three carboxypeptidases was revealed. It was found that SO4(2-) ion occupies the same position in the S1' subsite as the C-terminal carboxy group of the substrate.
3.Concise synthesis of PM-94128 and Y-05460M-A.
Enomoto M1, Kuwahara S. J Org Chem. 2009 Oct 2;74(19):7566-9. doi: 10.1021/jo9014968.
The enantioselective total synthesis of PM-94128, a potent cytotoxin of microbial origin, was accomplished by a concise nine-step sequence of reactions in 14% overall yield from N-Boc-l-leucine. The synthesis of Y-05460M-A, a one-carbon lower homologue of PM-94128, was also achieved from N-Boc-l-valine by the same approach, which enabled its stereochemical determination.
