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Characterization of selachian egg case collagen
T T Luong1, M M Boutillon, R Garrone
1King Alfred's University College, Winchester, Hants, SO22 4NR, United Kingdom.
Biochemical and Biophysical Research Communications
|October 24, 1998
Summary
Researchers identified a novel collagen in dogfish shark egg cases, secreted by the oviducal gland. This collagen provides structural integrity and permeability, with unique sequences suggesting new protein families.
Area of Science:
- Biochemistry
- Structural Biology
- Marine Biology
Background:
- Dogfish shark (Scyliorhinus canicula) egg cases are tough, permeable collagenous structures.
- The oviducal gland's D-zone secretes the collagenous lamellae forming the egg case wall.
Purpose of the Study:
- To characterize the collagenous components of the dogfish shark egg case.
- To investigate the biochemical properties and sequence of the collagen secreted by the oviducal gland.
Main Methods:
- Extraction and partial purification of acid-soluble collagen from the oviducal gland D-zone.
- Native gel electrophoresis and SDS-PAGE to assess protein components and molecular weight.
- Amino acid analysis to determine composition.
- Edman degradation for N-terminal and internal peptide sequencing.
Main Results:
- A single collagen band was identified on native gels, with SDS-PAGE revealing major (35 kDa) and minor (34 kDa) components.
- The collagen was not glycosylated and had an amino acid composition rich in glycine and imino acids.
- Novel collagenous peptide fragments with G-X-Y triplets showed similarity to mammalian type IV, X, and VI collagens.
- Unique noncollagenous sequences were identified, with potential N-myristoylation and phosphorylation sites.
Conclusions:
- The dogfish oviducal gland secretes a unique collagen contributing to the egg case's mechanical properties and permeability.
- The identified collagen sequences represent potentially novel protein families with implications for structural protein evolution.