NAGAYAMA Protein Array

nagayama_portrait

The Nagayama Protein Array project attempted to establish a universal technology for fabricating two-dimensional protein arrays in the form of crystalline or amorphous films having specifically desired molecular orientations and alignments.

Research Director: Dr.Kuniaki Nagayama
(Professor College of Arts and Sciences The University of Tokyo)
Research Term 1990-1995

Research Results

Supramolecules:

  • A new architecture of nature involving carbohydrate gluing (polysacchride-lectin like binding) was established for the supramolecular assembly of huge proteins comprising about 200 protein subunits, giant hemoglobin from annelid.
  • Covalently bonded dimers and trimers of ribonuclease H were synthesized through genetic fusion by gene engineering and chemical fusion by trifunctionals, which connect three monomers through surface cysteins.
  • Liposomes were used as templates to assemble ferritin molecules by introducing lock-and-key interactions: avidin-biotin and lectin-polysaccharide. Virus-like protein vesicles were organized by tailoring specific (lock-and-key) and non-specific (electrostatic) interactions.

Particle and Protein Assembly

  • A novel fabrication principle applicable to colloidal particles including proteins for their two-dimensional self-assembly was found. Particles which are mobile in thin liquid films possessing a thickness comparable to the particles were assembled and hexagonally packed into crystalline arrays. The continuous growth of a monolayer of particle arrays with crystalline order was obtained with a simple apparatus by only vertically dipping and withdrawing a wettable glass to and from a colloid suspension.

Two-dimensional Protein Crystals

  • Thick liquid film systems for preparing protein 2D arrays were developed by employing the secondary minimum induced by the electric potential near the charged surface.
  • Hexagonal, tetragonal and oblique lattice ferritin 2D crystals were prepared on thin liquid films developed on a glucose solution by tailoring interprotein interactions through introducing mutations on protein surfaces.

Characterization and Simulation of Arrays

  • A color ellipsocope was developed to monitor the in situ growth of protein arrays.
  • Various VIDEO microscope techniques were developed to monitor film formation, particle-array formation and protein-array formation.
  • The function of ferritin, ferroxidase activity, in 2D crystals made on mercury and transferred to a carbon film in the dry form was monitored by a new method: electron microscopic assay of the function for a single protein.
  • Crystal stability by electrostatic interactions were legitimated by computer simulation for real 3D crystals of three proteins: insulin, basic pancreatic trypsin inhibitor and ferritin.
  • A poker-chip model used to study the physical aspects of molecular-assembly and molecular interactions was intensively developed.

graph1

·Continuous production of large-size mono-particle arrays by convective assembly.Vw: film production speed,Je: water evaporation rate,Jw:water influx,Jp:particle influx. The inset is a video-microscopic view of the array growth.

graph2

·2D crystallization of proteins in a thin aqueous film developed on a glucose solution (water-on-water method).

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