Crystine: fibrous biomolecular material from protein crystals cross-linked in a specific geometry

Protein Eng. 2002 Nov;15(11):895-902. doi: 10.1093/protein/15.11.895.


Cysteine substitutions were engineered on the surface of maltose binding protein to produce crystine fibers, linear polymers of folded protein formed within a crystal. Disulfide bond formation between adjacent protein molecules within the lattice was monitored by X-ray crystallography. The cross-linked crystals were resistant to dissolution in water or neutral buffer solutions, even though the cross-linking was one-dimensional. However, crystine fibers were observed by transmission electron microscopy to dissociate from the crystals in acidic solutions. Some fibers remained associated as two-dimensional bundles or sheets, with a repeat unit along the fibers consistent with the packing of the individual protein molecules in the crystal. Neutralization of the acidic solutions caused the fibers to re-associate as a solid. Crystine threads were drawn out of this solution. In scanning electron microscopy images, many individual fibers could be seen unwinding from the ends of some threads. Crystine fibers are a new type of biomolecular material with potential applications wherever the use of proteins in a fibrous form is desirable, for example, the incorporation of enzymes into cloth or filtration material.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics
  • Carrier Proteins / ultrastructure
  • Crystallization
  • Crystallography, X-Ray
  • Maltose-Binding Proteins
  • Microscopy, Electron
  • Mutation
  • Structure-Activity Relationship


  • Carrier Proteins
  • Maltose-Binding Proteins