The 22nd Amino Acid

  title={The 22nd Amino Acid},
  author={John F. Atkins and Raymond F. Gesteland},
  pages={1409 - 1410}
Images of the human brain. (A) Five-year-old child in an MRI scanner. (B) Recent noninvasive MRI methods measure the function and structure of a child’s brain. The top row depicts patterns of brain activity indexed by fMRI in three representative axial (Z) slices. The bottom row shows corticospinal white-matter fiber tracts (green) projecting through the same three axial slices measured by DTI. 

Brain plasticity, learning, and developmental disabilities.

  • B. Casey
  • Psychology, Biology
    Mental retardation and developmental disabilities research reviews
  • 2003
This special issue provides animal models of behavior and brain development, applications of noninvasive imaging and genetic methods to human brain development and behavior, and select reviews of how these models and methods have been applied to the examination of developmental disabilities.

Blurring the lines between ribosomal and nonribosomal peptide scaffolds.

  • C. Walsh
  • Biology, Chemistry
    ACS chemical biology
  • 2014
The recent discoveries that bottromycins and polytheonamides, containing β-methyl and D-amino acid residues, are of Ribosomal origin blur the distinctions between peptide structures derivable by ribosomal and nonribosomal assembly lines and reveal new chemistry for posttranslational maturation of proteins.

Nucleic Acids Structure Minitutorial

It is difficult to imagine today that it was only a few decades ago when Watson and Crick reported their description of the DNAdouble helix, based on analysis of DNA fiber diffraction patterns and Chargaff’s rules, which described a spiral image of an orderly helix.

Protein Structure Introduction

The term “protein” originates from the Greek word proteios, meaning “primary” or “of first rank”. The name was adapted by Jons Berzelius in 1838 to emphasize the importance of this class of

Primer on medical genomics. Part IV: Expression proteomics.

This article reviews the area of expression proteomics, which catalogues the relative abundance of proteins and characterizes the 3-dimensional structure of proteins in a given cell or organism within a given environment and at a specific stage in the cell cycle.

A Universal HPLC-MS Method to Determine the Stereochemistry of Common and Unusual Amino Acids.

  • S. Hess
  • Chemistry, Biology
    Methods in molecular biology
  • 2019
A state-of-the-art indirect chromatography-based LC-MS method for stereochemistry of amino acids formed from amino acids that were reacted with chiral derivatizing agents and separated on a reversed phase column using mass spectrometry compatible buffers.

Stereoselective peptide analysis

The stereochemistry of a peptide determines its spatial features and can profoundly influence its chemical properties and biological activity, so a substantiated knowledge of the underlying molecular recognition mechanism will be helpful in understanding existing and developing new stereoselective analysis systems.

Future of Enzymology: An Appraisal

The importance of understanding enzyme function in vivo is very much appreciated now; this will form one of the frontiers in enzymology.

Life's jokers

1986 was another scoop year, when it was discovered that the UGA codon could produce a new amino acid altogether: selenocysteine, the 21 st amino acid, which is found in archaea, eubacteria and an imals.



The structure of the mouse glutathione peroxidase gene: the selenocysteine in the active site is encoded by the ‘termination’ codon, TGA.

The identification of a genomic recombinant as encoding the entire mouse GSHPx gene is reported, and the selenocysteine in the active site of the enzyme is encoded by TGA.

Expanding the Genetic Code of Escherichia coli

A unique transfer RNA/aminoacyl-tRNA synthetase pair has been generated that expands the number of genetically encoded amino acids in Escherichia coli and should provide a general method for increasing the genetic repertoire of living cells to include a variety of amino acids with novel structural, chemical, and physical properties not found in the common 20 amino acids.

The renaissance of aminoacyl‐tRNA synthesis

The role of tRNA as the adaptor in protein synthesis has held an enduring fascination for molecular biologists, but recent developments in genomics and structural biology have revealed an unexpected array of new enzymes, pathways and mechanisms involved in aminoacyl‐tRNA synthesis.

Recoding: dynamic reprogramming of translation.

A minority of genes in probably all organisms rely on "recoding" for translation of their mRNAs. In these cases, the rules for decoding are temporarily altered through the action of specific signals

Selenocysteine incorporation directed from the 3'UTR: characterization of eukaryotic EFsec and mechanistic implications.

Key questions about the mechanistic details and efficiency of this intriguing process can begin to be addressed, through identification of the factors catalyzing cotranslational selenocysteine insertion in eukaryotes.

Identification and characterisation of the selenocysteine-specific translation factor SelB from the archaeon Methanococcus jannaschii.

It is speculated that in Archaea the functions of bacterial SelB are distributed over at least two proteins, one, serving as the specific translation factor, like MJ0495, and another one, binding to the SECIS which interacts with the ribosome and primes it to decode UGA.

Nucleotide sequence and expression of the selenocysteine-containing polypeptide of formate dehydrogenase (formate-hydrogen-lyase-linked) from Escherichia coli.

The results are consistent with a co-translational selenocysteine incorporation mechanism.

Pyrrolysine Encoded by UAG in Archaea: Charging of a UAG-Decoding Specialized tRNA

Results indicate that pyrrolysine is the 22nd genetically encoded natural amino acid to be encoded by the UAG codon in methylamine methyltransferase genes of Methanosarcina barkeri.

A New UAG-Encoded Residue in the Structure of a Methanogen Methyltransferase

The UAG-encoded residue in a 1.55 angstrom resolution structure of the Methanosarcina barkerimonomethylamine methyltransferase (MtmB) reveals a homohexamer comprised of individual subunits with a TIM barrel fold that appears consistent with a lysine in amide-linkage to (4R,5R)-4-substituted-pyrroline-5-carboxylate.