Isolation And Characterization Of Pepsin-soluble Collagen From The Abalone (Haliotis Discus Hannai Ino)

Abalones belonging to the Mollusk Gastropoda of invertebrate are traditional tonic consumed by Chinese and Japanese because of it's high nutritional. Recently, the enlarging of abalone aquiculture and output are remarkable. There are about 216 kind of abalones in the world and about 7 in China. Haliotis discus hannai is the best of edible abalones distributed in the seaside of North China. In the foot of abalone muscle, collagen content was parallel with muscle toughness. Pepsin-soluble collagen (PSC) was extracted from the foot of abalone and its characterisation was studied.First, PSC was extracted from the foot of Haliotis discus with yield of 8.72%, on the basis of dry weight. The maximum absorption wavelength of PSC in the near ultraviolet region was 232 nm. FTIR (fourier transform infrared spectroscopy) investigations confirmed the existence of helical arrangements in PSC of abalone foot. Native collagen gave a characteristic CD (circular dichroism) spectrum with a positive extreme at 221 nm and a negative peak that appeared at 199 nm, which was typical of the collagen triple-helix structure.Second, PSC were analyzed for molecular weight by SDS-PAGE, amino acid composition and the primary structure of fragment. The molecular masses of the collagen subunits were about 175 kDa for a chain. SDS-PAGE manifested that the PSC contained a1 and small amounts of a2 chains. Q-TOF2 MS as a powerful tool has been applied to the characterization of the fragment. The results showed that peptides GEVGPSGPAGLTGQR, GDAGAQGLIGMPGER, GPSGPSGEVGQSGPPGPAGAR, LGIIGQEGK, GLSGTIGPNPLAGR, VGPSGLLGLQGPAGPSGEDGGNHR were the typical primary structure of collagen-G-X-Y-repeats.Third, Maximum solubility in 0.5 M acetic acid was observed at pH 2. Solubility reached the minimum at pH 5. A sharp decrease in solubility was observed in 2%(w/v) NaCl or above. The denaturation temperature (Td) of PSC from the foot of abalone was about 22.7?.The structure changes of PSC in solution appeared mainly between 20? and 35?. When the treated temperature was increased to 35? or above the CD spectra curve was severe changed. The positive peak was vanish and negative peak became weaker. Their peak form was appeared a little shift. These phenomenons indicted that the PSC triple helical stereochemical structure was destroyed when the treatment temperature up to 35? or above for 10 minutes. The triple helical has become the random coil.Last, the functional properties and biological activity of PSC were investigated. Concentration of 0.03%, pH 3.0-3.5 of the PSC up to 110% of foaming, foam stability is poor. Emulsion was 100%, but the emulsion stability in general, placed after the 5h, only kept at about 50%. PSC has a high Fe2+ chelating activity, its IC5o value of 0.348 mg/mL, a concentration of 1.2 mg/mL when the chelating capacity of up to 91.62%. The DPPH radicals scavenging rate of PSC was 41.6% at concentration of 3 mg/mL. The ACE inhibitory activity of PSC increased with PSC concentration.