Bovine chymotrypsinogen

Cytochrome c (bovine heart) Myoglobin (horse heart) Chymotrypsinogen (bovine pancreas) /3-Lactoglobulin (goat milk)... 

Wang, D., Bode, W., Huber, R. Bovine chymotrypsinogen A. X-ray crystal structure analysis and refinement of a new crystal form at 1.8 A resolution. /. Mol. Biol. 

Chymotrypsin has also been utilized to promote debridement, as well as the reduction of soft tissue inflammation. It is also used in some opthalmic procedures, particularly in facilitating cataract extraction. It is prepared by activation of its zymogen, chymotrypsinogen, which is extracted from bovine pancreatic tissue. 

Figure 4.8 Cation-exchange liquid chromatography of basic proteins. Column, Asahipak ES502C eluent, 20 min linear gradient of sodium chloride from 0 to 500 mM in 50 mM sodium phosphate buffer pH 7.0 flow rate, 1 ml min-1 temperature, 30 °C detection, UV 280 nm. Peaks 1, myoglobin from horse skeletal muscle (Mr 17 500, pi 6.8-7.3) 2, ribonuclease from bovine pancreas (Mr 13 700, pi 9.5-9.6) 3, a-chymotrypsinogen A from bovine pancreas (Mr 257 000, pi 9.5) and 4, lysozyme from egg white (Mr 14 300, pi 11.0-11.4). (Reproduced by permission from Asahikasei data)...

How long are the polypeptide chains in proteins As Table 3-2 shows, lengths vary considerably. Human cytochrome c has 104 amino acid residues linked in a single chain bovine chymotrypsinogen has 245 residues. At the extreme is titin, a constituent of vertebrate muscle, which has nearly 27,000 amino acid residues and a molecular weight of about 3,000,000. The vast majority of naturally occurring proteins are much smaller than this, containing fewer than 2,000 amino acid residues. 

Hydrolysis of peptides or proteins with acid yields a mixture of free a-amino acids. When completely hydrolyzed, each type of protein yields a characteristic proportion or mixture of the different amino acids. The 20 common amino acids almost never occur in equal amounts in a protein. Some amino acids may occur only once or not at all in a given type of protein others may occur in large numbers. Table 3-3 shows the composition of the amino acid mixtures obtained on complete hydrolysis of bovine cytochrome c and chymotrypsinogen, the inactive precursor of the digestive enzyme chymotrypsin. These two proteins, with very different functions, also differ significantly in the relative numbers of each kind of amino acid they contain. 

Amino acid Bovine cytochrome c Bovine chymotrypsinogen... 

Figure 2-30 Plot of hydropathy index versus sequence number for bovine chymotrypsinogen. The indices for individual residues have been averaged nine at a time. The solid bars at the top of the plot mark interior regions as determined by crystallography. The solid bars below the plot indicate regions that are on the outside of the molecule. From Kyte and Doolittle.280...

Figure 5. Schematic of the role of limited hydrolysis in the conversion of bovine chymotrypsinogen A to ir-, 8-, and a-chymotrypsins (32)...

Cytochrome c, lysozyme, myoglobin, ribonuclease A Cytochrome c mixture (horse, tuna, chicken, and bovine) Cytochrome c mixture (horse, tuna, chicken, and bovine) Trypsinogen, a-chymotrypsinogen, ribonuclease A, cytochrome c... 

Titration curves for bovine a-chymotrypsinogen have been determined under a variety of conditions by Wilcox (1961). The results are summarized in Table IX. The spectrophotometric titration of the phenolic groups is shown in Fig. 4. 

Fig. 1. Chromatography of bovine pancreatic juice on DEAE-cellulose (anionic proteins) and Amberlite IRC-50 (cationic proteins) (1). RNAase, ribonuclease ChTg-a, chymotrypsinogen A Tg, trypsinogen ProCp-B and Cp-B, procarboxypeptidase B and carboxypeptidase B DNAase, deoxyribonuclease ProCp-A, procarboxypeptidase A.

These results give, for the first time, reliable information about the general composition of bovine juice. Its content of proteolytic enzymes is strikingly high (about 72 % of the total proteins). Chymotrypsinogen B, which was formerly considered as a minor constituent, is very abundant. On the other hand, bovine juice is quite poor in amylase and lipase. 

The study of the terminal residues of bovine chymotrypsinogen A is beset with unusual difficulties. The NHs-terminal half-cystine cannot be found unless the protein is oxidized by performic acid (66). It is not split... 

Fio. 7. Stepwise formation of the three chains of a-chymotrypsin (A ) (64). ChTg, bovine chymotrypsinogen A. ChT-jr, -i and -a, respectively, ir-chymotrypsin (Ai), S-chymotrypsin (Aj), and -chymotrypsin (Ad. Neo-ChTg, neochymotrypsinogens (degraded and still activatable forms of chymotrypsinogen A). + and —, NHs- and COOH-terminal residues, respectively. T.C. and C.C., hydrolysis catalyzed by trypsin and chymotrypsin, respectively. Asp, asparagine residue. A, B, and C, chains A, B, and C of a-chymotrypsin (Ad. 

Table I gives the amino acid composition of bovine chymotrypsinogen A. Quite similar results for most amino acids have been obtained for this protein in two laboratories by the usual chromatographic technique in its manual or automatic (83) form involving all the necessary corrections and extrapolations to zero time. Cystine has been determined as cysteic acid after pcrformic acid oxidation. Values of tryptophan are probably less satisfactory sin( e they are derived from spectrophotometric or microbiological determinations. The protein contains only 2 histidines, 2 methionines, 4 arginines, 4 tyrosines, and 5 cystines per mole.

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