Purification and self-assembly of natural coiled-coil proteins from marine snail pugilina cochlidium egg case membranes

Abstract

Pugilina cochlidium is a marine snail that can lay a string of egg capsules made of an elastic biomaterial that encapsulates and protects the embryos from the harsh marine environments. Previous studies on Busycotypus canaliculatus, a different species of marine snail has found that the egg capsule is resilient and has shock absorbing properties. It exhibited elastic recovery which is non-entropy driven.

The objective of this project is to extract and purify egg capsule precursor proteins found in the nidamental gland of Pugilina cochlidium, and characterise the microstructure of the egg capsule wall.

The nidamental gland from a sedated Pugilina cochlidium was obtained by dissection. Reversed Phase – High Performance Liquid Chromatography (RP-HPLC) was then employed to separate the precursor proteins.

Individual fractions collected from the RP-HPLC were subjected to Sodium Dodecyl Sulfate – Polyacrylamide Gel Electrophoresis (SDS-PAGE) to determine the purity. Matrix-Assisted Laser Desorption/Ionisation – Time of Flight Mass Spectrometry (MALDI-TOF MS) was used to further determine the molecular weights of the proteins.

Optical microscope (OM), scanning electron microscope (SEM) and atomic force microscope (AFM) were used to characterise the structure of the egg capsule. Fibres were observed to have a banding periodicity. The mean values of the banding periodicity and fibre thickness were obtained.