Search

A multi-block copolymer comprises at least one hydrophilic collagen-like block and at least one silk-like block. The silk-like block comprises an amino acid sequence ((GA) m GX) n , wherein G is glycine, A is alanine, m and n are at least 2. X is an ionizable amino acid. The ionizable amino acid is inducible to bear a positive charge or a negative charge. The ionizable amino acid bearing the positive charge is preferably histidine and the one bearing the negative charge is preferably glutamic acid.

Disclosed is a block co-polypeptide comprising at least two blocks T and at least one block S, with blocks T and S alternating, wherein each T independently denotes a Trimerizing Block being a polypeptide block capable of forming a thermoreversible collagen-like triple helix structure, and whereineach S independently denotes a Spacer Block S being a polypeptide neither forming a collagen-like triple helix. The block co-polypeptide is capable of forming a gel, and is useful as an animal-free, biocompatible substitute for gelatin. Uniquely, the polypeptide allows the independent controlling of the melting temperature of the gel, the stiffness and crosslink density of the gel, the lower critical gel-forming concentration related to the length of the molecules, and unrelated (e.g. biological, physiological, pharmaceutical or signalling) functions of the molecule.

A tabular silver halide emulsion wherein the tabular grains account for more than 75% of the total grain projected area said emulsion comprising silver halide grains nucleated in the presence of nucleation peptizer and thereafter grown in the presence of growth peptizer, wherein at least one of the peptizers is substantially pure collagen like material prepared by genetic engineering of native collagen encoding nucleic acid, said peptizer having an amino acid sequence comprising more than 4 different amino acids. A process of preparing the AgX emulsion. A process of producing recombinant collagen like polypeptide comprising expression of a collagen like polypeptide encoding nucleic acid sequence by a microorganism to a degree exceeding 0.95 grammes /liter, said recombinant collagen being free of helix structure and preferably the expression occurring in a microorganism other than E. coli or Saccaromyces cerevisiae.