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Subunit structures of three human myeloperoxidases.
H Iwamoto1, Y Morita, T Kobayashi
1Research Institute for Food Science, Kyoto University.
Journal of Biochemistry
|April 1, 1988
Summary
Researchers characterized the heavy and light subunits of human myeloperoxidase (H2O2 oxidoreductase [EC 1.11.1.7]), revealing their terminal amino acid sequences and glycosylation patterns. This provides insights into enzyme structure and function.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Human myeloperoxidase (MPO) is a key enzyme in the innate immune system.
- Understanding MPO subunit structure is crucial for elucidating its catalytic activity and regulation.
Purpose of the Study:
- To isolate and characterize the heavy and light subunits of human myeloperoxidase.
- To determine the N-terminal and C-terminal amino acid sequences of both subunits.
- To investigate the glycosylation of the heavy subunits.
Main Methods:
- Isolation of reduced and S-carboxymethylated MPO subunits.
- Amino acid sequencing of N-termini and C-termini.
- Analysis of chemical composition and glycosylation.
Main Results:
- Identical terminal amino acid sequences and similar compositions were found for both subunits across three MPO forms.
- N-terminal sequences for heavy and light subunits were determined, with heterogeneity in the light subunit.
- C-terminal processing and the attachment of high mannose carbohydrate chains to heavy subunits were observed.
Conclusions:
- The heavy subunits likely span amino acids 279-744, and light subunits (164-167)-272.
- Post-translational modifications, including C-terminal processing and glycosylation, are significant for MPO structure and function.