Name:
Masumi Taki
Country:
Japan
City:
Chofu Tokyo
State/Province:
ACS Member:
true
Local Section:
International Chapter:
Technical Division Membership:
Organic Chemistry Division
Technical Division Membership Emeritus:
Subdivision Member:
ACS Activities:
Company/Institution Name:
Career Stage:
Professional
Research and Special Interests:
Our progress in regiospecific modification of macromolecules will be descibed below.
1) Proteins:
Position-specific incorporation of nonnatural amino acids through ribosomal systems can introduce functional groups into proteins at desired positions.1 By using multiple 4-base codons, we have successfully incorporated two nonnatural amino acids into single proteins.2 Alternatively, we have also incorporated the amino acids only at the N-terminus of a protein by the use of start AUG codon.3
Enzymatic modification of proteins without the participation of ribosomes is an alternative approach toward the position-specific introduction of functional groups. Taking advantage of loose substrate specificity in transglutaminase, fluorophores can covalently be attached to a specific tag of proteins.4
Besides, L/F-tRNA-protein transferase is known to catalyze the transfer of hydrophobic amino acids from tRNA to the N-terminus of a protein possessing lysine or arginine as the N-terminal residue. By using the L/F-transferase, we have achieved non-ribosomal N-terminal-specific coupling of nonnatural amino acids to proteins.5
2) Peptides:
Conventional solid-phase peptide synthesis is useful to incorporate two fluorescent amino acids into single proteins. We have synthesized the amino acids as FRET pairs,6 and introduced them into a single peptide containing a caspase-3 recognizing sequence.
Besides, L/F-transferase-mediated N-terminal-specific coupling of nonnatural amino acids to a peptide will be presented.7
3) Dumbbell-shaped DNA:
Dumbbell-shaped DNA molecules were synthesized by using a novel method, and a single fluorophore was attached only to a hairpin-loop region.8
4) [60]Fullerene:
Regio- and stereospecific functionalization on [60]fullerene was achieved. The [60]fullerene bisadducts possess two phenol moieties, which are applicable to further functionalization.9
References:1. Hohsaka, Sisido, JACS, 9778 (1996) ; 2. Taki, Sisido, JACS, 14586 (2002) ; 3. Taki, Taira, JBB, 149 (2001) ; 4. Taki, Taira, Protein Eng., 699 (2003) ; 5. Taki, Sisido, ChemBioChem, 1676(2006) and 719 (2008) ; 6. Taki, Sisido, PCT/JP2006/311561 (2006) ; 7. Taki, Sisido, Biopolymers, 267 (2007);
8. Taki, Taira, Angew. Chem. Int. Ed., 3160 (2004) ; Taki, Nishimura, JACS, 926 (1997).
Area of Expertise:
chemical biology, organic chemistry, protein engineering
Years of Expertise:
11-15