Calf prochymosin

Chymosin protease (1) Aspergillus niger var. awamori d-calf prochymosin gene (2) Escherichia coli K-12 d-calf prochymosin gene (3) Kluyveromyces marxianus cleaves a single bond in kappa casein cleaves a single bond in kappa casein 3.4.23.4... 

Chymosin (Aspergillus niger var. awamori, Escherichia coli K-12, and Kluyveromyces marxianus, each microorganism containing a calf prochymosin gene), 786, (S3)20 Chymotrypsin, 786, (S3)18 Chymotrypsin Activity, 793 Cinene, 518 1,8-Cineol, 496 Cineole, Percentage of, 818 Cinnamal, 468 Cinnamaldehyde, 468, 611 Cinnamic Acid, 468, 565, 612, (S3)66 Cinnamic Alcohol, 470 Cinnamic Aldehyde, 468 Cinnamon Bark Oil, Ceylon Type, 101, 578... 

The size distribution and density of inclusion bodies have been studied only for two proteins, calf prochymosin and y-interferon (64). The mean particle sizes of y-interferon and prochymosin inclusion bodies were O.Slgm with a standard deviation of 0.17gm and 1.28gm with a standard deviation of 0.46gm, respectively. The buoyant density of the y-interferon and prochymosin inclusion bodies was proportional to the density of the suspension medium indicating a relatively high voidage within the particles. The void fraction (=void volume/total volume) was 70% for y-interferon and 85% for prochymosin. 

Emtage JS, Angal S, Doel MT et al. (1983) Synthesis of calf prochymosin (prorennin) in Escherichia coli. Proc Natl Acad Sci USA 80(12) 3671-3675 Epstein W, Rothman-Denes LB, Hesse J (1975) Adenosine 3 5 -cycUc monophosphate as mediator of cataboUte repression in Escherichia coli. Proc Natl Acad Sd USA 72(6) 2300-2304 Erson B, Janson JC, Ryden L (1998) Introduction to protein purification. In Janson JC, Ryden L (eds). Protein purification principles, high-resolution methods, and applications, 2nd edn. Wiley-VCH, Weinheim, pp 3 0... 

Calf prochymosin, calf chymosin (calf prochym., calf chym.). NH2-terminus of the active enzyme is Gly-45. Residues 1-105 (60,61). S-S bridges and residues 357-373 (7). The rest of the sequence from Foltmann and coworkers unpublished results. Residue 290 is aspartic acid in chymosin A and glycine in chymosin B. 

Pepsinogen from porcine stomachs was purified to homogeneity (10) with a final step of chromatography on polylysine-Sepharose (11). Polylysine-Sepharose was made from polylysine (12) obtained from Cambrian Chemicals, Croydon, U. K. Bovine and canine pepsinogens, chicken pepsinogen, calf prochymosin, and pepstatin were very... 

Activation of Bovine, Canine, and Chicken Pepsinogens and Calf Prochymosin... 

In contrast, the peptide fraction from calf prochymosin has a composition (Table VI) resembling that of residues 1-27 in the prochymosin sequence (Fig.l). After removal of the excess of pepstatin on Bio-Gel P2, the prochymosin peptide had the composition shown in the last column of Table VI. For the sake of brevity the details of the protein fraction from prochymosin are not given but this showed a composition intermediate to prochymosin and chymosin, particularly in the values for lysine and leucine which reflect the largest changes. 

Amino acid Peptide from bovine pepsinogen Expected from sequence of residues 1-17 Peptide from calf prochymosin Expected from sequence of residues 1-27 Prochymosin peptide after Bio-gel P2... 

Thus, in the cases of bovine pepsinogen and calf prochymosin where the activation segment sequences are known, peptides were released corresponding to the NH2-terminal parts of the sequence only. For the canine and chicken proteins where no sequence data is available, it appears that inclusion of pepstatin stops the activations before all of the activation segment is released. Consequently, a sequential activation mechanism and not a one-step transformation must be operative with all five of these zymogens. 

By incubation of porcine, bovine, canine, or chicken pepsinogens and calf prochymosin with pepstatin at pH 2.5, the first active protein generated on activation is trapped in an inactive complex. The first activation peptide liberated from porcine pepsinogen has been identified as residues 1-16 whereas that from prochymosin is derived from residues 1-27. This suggests that pepsin and chymosin are not formed by one-step conversions from their zymogens, but by (different) sequential, activation mechanisms. 

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