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Merck

Silk microgels formed by proteolytic enzyme activity.

Acta biomaterialia (2013-06-13)
Sangram K Samal, Mamoni Dash, Federica Chiellini, David L Kaplan, Emo Chiellini
ABSTRACT

The proteolytic enzyme α-chymotrypsin selectively cleaves the amorphous regions of silk fibroin protein (SFP) and allows the crystalline regions to self-assemble into silk microgels (SMGs) at physiological temperature. These microgels consist of lamellar crystals in the micrometer scale, in contrast to the nanometer-scaled crystals in native silkworm fibers. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zeta potential results demonstrated that α-chymotrypsin utilized only the non-amorphous domains or segments of the heavy chain of SFP to form negatively charged SMGs. The SMGs were characterized in terms of size, charge, structure, morphology, crystallinity, swelling kinetics, water content and thermal properties. The results suggest that the present technique of preparing SMGs by α-chymotrypsin is simple and efficient, and that the prepared SMGs have useful features for studies related to biomaterial and pharmaceutical needs. This process is also an easy way to obtain the amorphous peptide chains for further study.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
α-Chymotrypsin from bovine pancreas, ≥40 units/mg protein, vial of 5 mg
Sigma-Aldrich
α-Chymotrypsin from bovine pancreas, Type II, lyophilized powder, ≥40 units/mg protein
Sigma-Aldrich
α-Chymotrypsin from bovine pancreas, (TLCK treated to inactivate residual tryspin activity), Type VII, essentially salt-free, lyophilized powder, ≥40 units/mg protein
Sigma-Aldrich
α-Chymotrypsin from bovine pancreas, suitable for protein sequencing, salt-free, lyophilized powder
Sigma-Aldrich
α-Chymotrypsin−Agarose from bovine pancreas, lyophilized powder, 2,000-3,500 units/g agarose (One ml gel will yield 65-120 units)
Sigma-Aldrich
α-Chymotrypsin from bovine pancreas, Type I-S, essentially salt-free, lyophilized powder