BACKGROUND The secretion of heterologous animal proteins in filamentous fungi is usually limited by bottlenecks in the vesicle-mediated secretory pathway. RESULTS Using the secretion of bovine chymosin in Aspergillus awamori as a model, we found a drastic increase (40 to 80-fold) in cells grown with casein or casein phosphopeptides (CPPs). CPPs are rich in phosphoserine, but phosphoserine its...

In the crystal structure of uncomplexed native chymosin, the beta-hairpin at the active site, known as 'the flap', adopts a different conformation from that of other aspartic proteinases. This conformation would prevent the mode of binding of substrates/inhibitors generally found in other aspartic proteinase complexes. We now report the X-ray analysis of chymosin complexed with a reduced bond i...

Purpose: To further investigate the binding of α−crystallin to other proteins as part of its chaperone-like activity, we studied interactions of α−crystallin with recombinant calf prochymosins and chymosin. Methods: Recombinant calf prochymosin B and one C-terminal mutant (PC+2, with two additional residues, Histidine-Glycine) were expressed as inclusion bodies in E. coli. Native and mutant pro...

The complete amino acid sequence of calf chymosin (rennin) (EC 3.4.23.4) has been determined. The sequence consists of a single peptide chain of 323 amino acid residues. The primary structure of the precursor part of calf prochymosin was published previously (Pedersen, V.B., and Foltmann, B. (1975) Eur. J. Biochem. 55, 95-103), thus we are now able to account for the total 365 amino acid residu...

The partitioning of chymosin (from Aspergilus niger) and pepsin (from bovine stomach) was carried out in aqueous-two phase systems formed by polyethyleneglycol-potassium phosphate. The effects of polymer concentration, molecular mass and temperature were analysed. The partition was assayed at pH 7.0 in systems of polyethyleneglycol of molecular mass: 1450, 3350, 6000 and 8000. Both proteins sho...

Camel milk requires more calf rennet than cow milk to coagulate and the relative amount of rennet needed varies widely (2, 8, 14, 16). Extracts of adult camel abomasa have been used to coagulate cow milk with success (5, 6, 7). However, these enzymes have not been tried on camel milk. Rennet extracts from lamb and cow calves were found to be more effective with the milk of the respective specie...

In this work, pressure-assisted enzymatic gelation was applied to milk proteins, with the goal of enhancing structure and stability pressure-created protein gels. High-pressure processing (HPP) at 600 MPa, 3 min, 5°C concentrate (MPC) samples 12.5% concentration, both in absence presence calf chymosin [up 60 IMCU (international milk-clotting units)/kg milk] or camel (up 45 IMCU/kg milk). Gel ha...

The cholera toxin (CT)-binding activity of purified κ-casein macropeptide (CMP) from bovine κ-casein was detected. In addition, a statistical model was developed to optimize the production of CMP. CMP was prepared by chymosin hydrolysis of κ-casein and a subsequent 3% trichloroacetic acid treatment. CMP was further fractionated in an ion-exchange column by FPLC. CT binding activity was eluted a...

Chicken pepsinogen was incubated at pH2.5 with pepstatin. The zymogen activated itself by a sequential mechanism and an intact peptide derived from residues 1-26 in the protein was released in the first step. This peptide was found to inhibit the milk-clotting activities of pig and chicken pepsins and calf chymosin but to different extents.

The activity of chymosin, plasmin, and Lactococcus lactis enzymes (cell envelope proteinase, intracellular peptidases, and glycolytic enzymes) were determined after 5-min exposures to pressures up to 800 MPa. Plasmin was unaffected by any pressure treatment. Chymosin activity was unaffected up to 400 MPa and decreased at 500 to 800 MPa. Fifty percent of control chymosin activity remained after ...