Study On Separation, Purification And Properties Of Protamine And Peptides From Sturgeon Sperm

As the statistics of China Fishery Yearbook say,the output of sturgeon aquaculture increases by about ten thousand tons per year recent years,not least the large scale of sturgeon aquaculture.The large amount of by-products directly discarded in sturgeon processing have caused resource wasting and environmental pollution problems.Fish sperm,as one of them,usually contains a lot of natural active protamine which is functional and valuable in natural bacteriostatic and medical assistance.This thesis is aimed to improve the comprehensive utilization of sturgeon sperm,at the same time,establish some theoretical basis about properties and structure characterizations for protamine study.The final conclusions are as follows:(1)First using fish sperm of sturgeon-oracle bone as raw material to extract protamine.The optimal conditions were: taking 6.2 times volume of 0.83 mol/L H2SO4 for use,keeping extraction at 35 ?for 0.5 h and then repeating 4 times of extraction.A mean yield of 11.3% was obtained under these conditions.The crude extract of protamine could be well purified through glucosan gel chromatography to become further extracted protamine,which showing good bacteriostatic activity with high purity of 86.1% and molecular weight of 10.8 ku.(2)The finally optimal conditions obtaining 8.9% of protamine peptides by enzyme hydrolysis method based on protamine were: the liquid-solid ratio was 40,adding 3.1% of papain,and reacting at p H 7.0,then keeping 55 ? for 8.3 h.The protamine peptides obtained had three components weighing 1.6 ku,3.4 ku and 9.3 ku.(3)Sturgeon protamine contains comprehensive amino acids.It is a relatively stable protein which starting to denature at about 84~93?.Random coil configuration is the main secondary structure of protamine.Except for the outstanding hydration properties,protamine showed good inhibitory effects on Escherichia coli,Staphylococcus aureus and Saccharomyces cerevisiae with MIC of 0.50%,0.70% and 1.00%,while making no evident effect upon Aspergillus flavus.As for peptides,the antimicrobial activity against the microorganisms above was greatly strengthened.Compared to tea polyphenols andpotassium sorbate,protamine showed more advantages with a broader microbial range.