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Human alpha S1-casein like protein: purification and N-terminal sequence determination
M Cavaletto1, A Cantisani, G Giuffrida
1Dipartimento Biologia Animale, Università di Torino, Italy.
Biological Chemistry Hoppe-Seyler
|February 1, 1994
Summary
Researchers identified a new human casein component in mature milk, distinct from typical beta- and kappa-caseins. This novel alpha s1-casein subunit shows high homology to casein found in other species.
Area of Science:
- Biochemistry
- Human milk composition
- Protein analysis
Background:
- Human milk casein is primarily composed of beta- and kappa-casein fractions.
- Previous research has focused on these major casein components.
Purpose of the Study:
- To identify and characterize novel casein components in human milk.
- To investigate the N-terminal sequence of a newly identified human casein subunit.
Main Methods:
- Human casein fractions were isolated from pooled mature milk using ultracentrifugation and acid precipitation.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was employed to analyze protein mobility.
- Protein purification to homogeneity was achieved for the identified component.
- N-terminal sequencing was performed to determine the amino acid sequence.
Main Results:
- A minor casein component with higher electrophoretic mobility than beta-casein was consistently identified.
- This novel component was successfully purified to homogeneity.
- The N-terminal sequence of the first 14 amino acid residues exhibited significant homology to alpha s1-casein from other species.
Conclusions:
- Human milk contains a previously unidentified casein subunit, homologous to alpha s1-casein.
- This finding expands the known casein repertoire in human milk.
- Further research is warranted to elucidate the functional role of this new casein component.