Tetrahydrofuran amino acids—versatile building blocks for unnatural biopolymers: lack of secondary structure in oligomeric carbopeptoids derived from a D-galacto-5-(aminomethyl) tetrahydrofuran-2-carboxylic acid

2000 ◽  
pp. 3655-3665 ◽  
Author(s):  
Dominic E. A. Brittain ◽  
Mark P. Watterson ◽  
Timothy D. W. Claridge ◽  
Martin D. Smith ◽  
George W. J. Fleet
Keyword(s):  
Amino Acids ◽  
Carboxylic Acid ◽  
Secondary Structure ◽  
Building Blocks

scholarly journals Synthesis of new Cα-tetrasubstituted α-amino acids

2009 ◽  
Vol 5 ◽  
Author(s):  
Andreas A Grauer ◽  
Burkhard König
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Aromatic Aldehydes ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Peptide Backbone ◽  
Aliphatic Aldehydes ◽  
New Class ◽  
Cyclic Amino Acids

Cα-Tetrasubstituted α-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic Cα-tetrasubstituted tetrahydrofuran α-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to give aldol products under the reaction conditions used, we were able to obtain the target cyclic amino acids in low to moderate yields and in some cases with good diastereoselectivity.

scholarly journals On the emergence of homochirality and life itself

2021 ◽  
Vol 43 (1) ◽  
pp. 4-12
Author(s):  
Jeffrey Skolnick ◽  
Mu Gao
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Hydrogen Bonding ◽  
Secondary Structure ◽  
Building Block ◽  
Building Blocks ◽  
Native State ◽  
Protein Properties ◽  
Life Itself

Many of life’s molecules including proteins are built from chiral building blocks. What drove homochiral building block selection? Simulations on demi-chiral proteins containing equal numbers of d- and l-amino acids show that they possess many modern homochiral protein properties. They have the same global folds and could do the same biochemistry, with ancient, essential functions being most prevalent. They could synthesize chiral RNA and lipids which formed vesicles. RNA eventually combined with proteins creating ribosomes for more efficient protein synthesis, and thus, life began. Increased native state stability from homochiral secondary structure hydrogen bonding helped drive proteins towards homochirality.

Transformation of the Carboxyl Group of an Amino Acid to Variously Substituted Imidazoles through a Davidson-Type Heterocyclization

Synthesis ◽  
2019 ◽  
Vol 51 (09) ◽  
pp. 1961-1968 ◽  
Author(s):  
Jim Küppers ◽  
Michaela Hympánová ◽  
Tim Keuler ◽  
Andreas Schneider ◽  
Gregor Schnakenburg ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Amino Acids ◽  
Amino Acid ◽  
Carboxylic Acid ◽  
Building Blocks ◽  
Carboxyl Group ◽  
Amino Group ◽  
Combinatorial Approach ◽  
X Ray ◽  
Imidazole Derivatives

The modification of amino acids leads to valuable building blocks for the synthesis of bioactive compounds. By keeping the amino group protected, the carboxylic acid functionality can be converted in two steps into an imidazole moiety via a Davidson-like heterocyclization. This reaction allows for a combinatorial approach, in which two positions at the heterocycle can be modified. Herein, we report the synthesis of such imidazole derivatives by employing N-protected cyclohexylalanine as the starting material. Different α-halo ketones were used and two points of diversity, positions 4 and 5, were examined. The structure of the final imidazole derivatives was confirmed by three X-ray crystal structure analyses and their protease inhibiting activities were evaluated.

Tetrahydrofuran amino acids: Secondary structure in tetrameric and octameric carbopeptoids derived from a D-allo 5-(aminomethyl)tetrahydrofuran-2-carboxylic acid

2000 ◽  
pp. 3666-3679 ◽  
Author(s):  
Natasha L. Hungerford ◽  
Timothy D. W. Claridge ◽  
Mark P. Watterson ◽  
Robin T. Aplin ◽  
Andres Moreno ◽  
...  
Keyword(s):  
Amino Acids ◽  
Carboxylic Acid ◽  
Secondary Structure

ChemInform Abstract: Tetrahydrofuran Amino Acids: Secondary Structure in Tetrameric and Octameric Carbopeptoids Derived from a D-allo 5-(Aminomethyl)tetrahydrofuran-2-carboxylic Acid.

ChemInform ◽  
2001 ◽  
Vol 32 (10) ◽  
pp. no-no
Author(s):  
Natasha L. Hungerford ◽  
Timothy D. W. Claridge ◽  
Mark P. Watterson ◽  
Robin T. Aplin ◽  
Andres Moreno ◽  
...  
Keyword(s):  
Amino Acids ◽  
Carboxylic Acid ◽  
Secondary Structure

CLASSIFICATIONS OF AMINO ACIDS IN PROTEINS BY THE SELF-ORGANIZING MAP

2005 ◽  
Vol 16 (10) ◽  
pp. 1609-1616 ◽  
Author(s):  
MOOKYUNG CHEON ◽  
MUYOUNG HEO ◽  
IKSOO CHANG ◽  
CHOONGRAK KIM
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Protein Structures ◽  
Building Blocks ◽  
Side Chain ◽  
Self Organizing Map ◽  
Energy Parameters ◽  
Physico Chemical ◽  
Body Energy ◽  
Self Organizing

We present the clustering properties of amino acids, which are building blocks of proteins, according to their physico-chemical characters. To classify the 20 kinds of amino acids, we employ a Self-Organizing Map (SOM) analysis for the Miyazawa-Jernigan (MJ) pairwise-contact matrix, the Environment-dependent One-body energy Parameters (EOP) and the one-body energy parameters incorporating the Ramachandran angle information (EOPR) over the EOP in proteins. We provide the new result of the SOM clustering for amino acids based on the EOPR and compare that with those from the MJ and the EOP matrix. All three kinds of energy parameters capture the leading role played by the hydrophobicity and the hydrophilicity of amino acids in protein folding. Our SOM analysis generally illustrates that both the EOP and the EOPR can provide the collective clustering of amino acids by the side chain characteristics and the secondary structure information. However, EOP is better at classifying amino acids according to their side chain characteristics whereas EOPR is better with secondary structure. We show that the EOP and the EOPR matrix manifests more detailed physico-chemical classification of amino acids than those from the MJ matrix, which does not contain a local environmental information of amino acids in the protein structures.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</p>

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