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Various forms of mouse lactoferrins: purification and characterization.
1Institute of Biochemical Sciences, College of Science, National Taiwan University, Academic Sinica, Taipei.
Summary
This study investigated mouse lactoferrin (LF) heterogeneity, identifying distinct LF forms (LF1, LF2, LF3) in reproductive tissues. These forms exhibit variations in molecular weight and N-terminal sequences, indicating microheterogeneity within mouse lactoferrin.
Area of Science:
- Biochemistry
- Immunology
- Proteomics
Background:
- Lactoferrin (LF) is an iron-binding glycoprotein with diverse biological functions.
- Understanding LF microheterogeneity is crucial for elucidating its specific roles in different tissues.
- Previous studies have suggested variations in LF structure, but detailed characterization remains incomplete.
Purpose of the Study:
- To investigate the microheterogeneity of mouse lactoferrin (LF).
- To purify and characterize different forms of LF found in mouse reproductive tissues.
- To determine the distribution of LF in various non-sexual and sexual organs.
Main Methods:
- Ion-exchange HPLC and affinity chromatography for LF purification.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular weight determination.
- Automated Edman degradation for N-terminal amino acid sequencing.
- Western blot analysis for immunodetection of LF in tissue homogenates.
Main Results:
- Two distinct LF forms (LF1, LF2) were purified from uterine luminal fluid, and a third form (LF3) from epididymis homogenate.
- LF1 and LF2 showed a Mr 74,000 band, while LF3 showed a Mr 70,000 band on reducing SDS-PAGE.
- All LF forms were reduced to a Mr 68,000 band after N-glycosidase F digestion, indicating glycosylation.
- N-terminal sequencing revealed identical amino acid sequences for the first 19 residues, with minor differences in LF1.
- LF was detected in various non-sexual organs (kidney, spleen, lung, heart, liver) and sexual glands (epididymis, vagina, uterus, ovary, prostate).
Conclusions:
- Mouse lactoferrin exhibits significant microheterogeneity, with distinct forms present in different reproductive tissues.
- These LF variants differ in molecular weight and N-terminal structure, likely due to post-translational modifications.
- LF is widely distributed in various organs, suggesting diverse physiological roles beyond its known antimicrobial and immune functions.