Studies On The Preparation Of Collagen Peptides From Crocodile Bone And Their Functions

The Crocodile bone contains a lot of collagen.The Crocodile bone collagen peptide was obtained by enzymatic hydrolysis of Crocodile bone gelatin.We made collagen polypeptide through optimizing protein enzymes and controlling the process of hydrolysis.At the same time we can get good economic and social benefits.Acid-soluble collagen(ASC)was isolated from Crocodile bone.The maximum absorption of the crocodile collagen was 220nm on ultraviolet spectrophotometry.SDS-PAGE showed that the crocodile bone collagen contained ???1 and ?2 chain.With the analysis of amino acid composition,we found the crocodile bone collagen was typically collagen.Firstly,the appropriate protease and conditions of hydrolysis were selected out to gain biochemical polypeptide with the single factor experiments.The collagen peptide was prepared under the following condition that was bone collagen was hydrolyzed at natural pH(about 7.6)with papain protease 1.6%and keeping reacting 4 hours at 55?.The amino acids of polypeptide were abundant,in which the content of hydroxyproline was about 12.38%,and beneficial metal elements were very rich.The antioxidant activities of different concentration collagen peptides were determined.The results showed that:the IC50 of scavenging DPPH radical and hydroxyl radical were 1.33 mg/mL and 11.6 mg/mL,respectively.The relative reducing power of bone collagen peptide at 2 mg/mL was 620%.The influences of the bone collagen peptide on the malonaldehyde(MDA)content in mice red blood cell,mice liver mitochondria and mice tissue juice were studied.The results showed that:the collagen peptide could reduce the contents of MDA generated by mice red blood cell,mice liver mitochondria and mice tissue juice during warm-bathing.It was purified by using column chromatography on Sephadex G-25 which we called P2 and its antioxidant ability had improved.The IC50 on DPPH was 0.17 mg/mL.P2 at 1.0 mg/mL had protective effect to the hydroxyl-radical-induced DNA damage.By using the method of dynamics,we found that the collagen peptide showed significant inhibitory effect on Tyrosinase,the value of IC50 was 175?g/mL and the inhibitory type belonged reversible mixed.We found that P2 did not inhibit growth of B16 cells,thus it was a safe additive with potential function of whitening skin.Secondly,taking the inhibition rate of ACE as the criterion,using the Crocodile bone as the raw materials,the technical parameters of preparation of collagen peptides were optimized by the single factor experiments,which were as follows:the condition for hydrolysis was with alkaline protease 1.6%and keeping reacting 4 hours at 55?.It was purified by using column chromatography on Sephadex G-25 which we called M3.The IC50 on ACE of M3 was 1.74 mg/mL,had improved 3.4 rate compared with the original solution.ACE inhibition kinetics study found that M3 was an anticompetitive inhibitor.Digestive stability test showed that ACE inhibitory activity was stability because the mixture could not be hydrolysis easily by digestive enzymes.