Amino acid composition and zinc content of milk-clotting protease from Bacillus mesentericus strain 76

Area of Science:

• Biochemistry and enzymology
• Microbial protein characterization

Background:

• Bacillus mesentericus proteases are utilized in food processing.
• Characterization of microbial enzymes is crucial for understanding their industrial applications.

Purpose of the Study:

• To determine the biochemical properties of a milk-clotting protease from Bacillus mesentericus strain 76.
• To elucidate the amino acid composition and structural features of the enzyme.

Main Methods:

• Amino acid composition analysis.
• Enzyme activity assays.
• Denaturation studies using acetic acid.

Main Results:

• The protease is a single peptide chain of 304 residues, free of carbohydrates, cysteine, and cystine.
• Aspartic acid, threonine, serine, glycine, and alanine constitute 50% of the residues.
• The enzyme contains 35 aromatic and 103 ionic amino acids.
• A constant Menzyme:Azinc ratio of 1:1 was observed, indicating zinc ions remain after acid denaturation.

Conclusions:

• The milk-clotting protease from Bacillus mesentericus strain 76 possesses a unique amino acid profile.
• Zinc ions are tightly bound to the enzyme structure, persisting even after denaturation with 0.1 M acetic acid.