Studies on mammalian intestinal peroxidase

Area of Science:

• Biochemistry
• Enzymology

Background:

• Peroxidases are crucial enzymes involved in various biological processes.
• Intestinal peroxidases play roles in host defense and metabolism.
• Characterization of mammalian intestinal peroxidases is essential for understanding their functions.

Purpose of the Study:

• To purify and characterize peroxidase from rat small intestine.
• To compare the properties of rat intestinal peroxidase with those of pig intestinal enzyme.
• To investigate the inhibitory effects of benzhydroxamic acid on intestinal peroxidases.

Main Methods:

• Purification of rat intestinal peroxidase using polyacrylamide-gel electrophoresis.
• Spectroscopic analysis to determine absorbance ratio and molecular weight.
• Enzyme kinetics studies to determine the velocity constant for hydrogen peroxide reaction.
• Inhibition assays using benzhydroxamic acid and guaiacol as substrates.

Main Results:

• Rat intestinal peroxidase was purified to homogeneity with specific spectral properties.
• The enzyme exhibited a molecular weight (Mr) of 44000 +/- 1000, similar to pig intestinal peroxidase.
• The velocity constant for the reaction with hydrogen peroxide was 1.8 x 10(7) M-1 . s-1.
• Benzhydroxamic acid inhibited both rat and pig intestinal peroxidases, with the rat enzyme requiring a higher concentration for half-inhibition.
• Amino acid composition of pig intestinal peroxidase was determined, showing similarity to lactoperoxidase.
• The initial ten amino acid residues of pig intestinal peroxidase were sequenced.

Conclusions:

• Rat intestinal peroxidase shares similarities with pig intestinal enzyme but exhibits differences in sensitivity to benzhydroxamic acid inhibition.
• The findings provide insights into the structural and functional characteristics of mammalian intestinal peroxidases.
• Partial amino acid sequencing offers a foundation for further structural and evolutionary studies of these enzymes.