Studies on the Antibacterial Activity of Enzymatic Hydrolyzates of Lactoferrin Derived from Bovine Colostrum

유우 Lactoferrin 효소가수분해물 항균 활성에 관한 연구

The investigative research on the mammalian milk purely consisted of the physiological quality of lactoferrin was conducted to reveal the antimicrobial ativity of specifically functional foods with antibiotic characteristics as a basic data in food manufacturing. Bovine lactoferrin were isolated from raw milk samples, and was digested with pepsin, trypsin and chymotrypsin. It was necessary then to separate and purify lactoferrin from bovine raw milk, and in order to analyze the antimicrobial activity of the enzyme-treated bovine lactoferrin in their required quantitative fraction. Afterwards Escherichia coli and Staphylococcus aureus was incubated in it. It was that investigated to enzyme-treated fractions molecular weight and the peptide fragment with antimicrobial effect. 1. The purity of enzyme-treated bovine lactoferrin(BLF) was tested by SDS-PAGE. As a results of 12% SDS-PAGE assay, pepsin-treated LF did not exhibited band until if reaches 14 KDa, while trypsin and chymotrypsin treated LF, known to contain the non-digestive lactoferrin exhibited band at a molecular weight of 33 KDa. 2. Bovine lactoferrin was sucessfully purified through the use of Sephadex G-50 Column. In order to assay LF through the Sephadex G-50 column chromatography, the digestive bovine lactoferrin (BLFs) was eluted with a linear gradient of 0.05% Tris-HCl. When the gel-filtration analysis, pepsin, trypsin and chymotrypsin treatments of BLF fragments was showed 2, 3, and 2 peak, respectively. The results of the HPLC analysis confirmed that had a non-digestive lactoferrin receptor, and trypsin and chymotrypsin treated BLFs has an antimicrobial effect. 3. To measure the strength of the antimicrobial effect of enzyme treated lactoferrin it was compared to the antimicrobial activity taking place at the incubated Escherichia coli and Staphylococcus aureus. This might explain the resistance of the microorganisms for peptide fragment. The pepsin-treated of bovine lactoferrin was markedly reduced by incubation of the cells. Trypsin-treated of BLF was similar to chymotrypsin-treated of BLF. However, trypsin and chymotrypsin treatments of BLFs were showed the antimicrobial effect until eight hours incubation for native bovine lactoferrin. Therefore the enzyme-treated lactoferrin have an antimicrobial effect even non-digestive lactoferrin. 4. The digestive bovine lactoferrin fragments assay was carried out by the use of Sephadex G-50 column chromatography and SDS-PAGE. The pepsin and chymotrypsin-treated fragments has a low molecular weight and trypsin-treated lactoferrin was only showed a band. It was described that characteristics of digestive protein. It appeared that there may be a relation between virulence and resistance to enzyme-treated BLF.

본 연구는 포유동물의 젖에 함유되어 있는 lactoferrin(LF)의 생리적 특성을 밝혀 기능성 식품 특히 항균작용을 이용한 식품제조업에의 이용을 위한 기초자료를 얻고자 실시하였다. 따라서 젖소의 초유로부터 lactoferrin을 분리 정제하여, 소화부위에 따른 lactoferrin의 항균활성을 분석하고자 pepsin, trypsin 및 chymotrypsin으로 분해하여 lactoferrin의 항균력을 측정하고, gel-filtration으로 분리 정제된 각각의 fraction별로 단백질을 정량하여 Escherichia coli와 Staphylococcus aureus에 접종하여 항균효과를 지니는 각 효소별 fraction의 분자량과 peptide fragment를 검토하였다. 1. 젖소의 초유로부터 분리 정제된 lactoferrin(LF)을 단백질 분해 효소인 pepsin, trypsin 및 chymotrypsin으로 분해한 결과 bovine lactoferrin은 SDS-PAGE를 수행하여 band를 확인할 수 있었다. pepsin으로 분해된 lactoferrin은 분자량 14KDa까지에서도 band를 확인할 수가 없었으며, trypsin과 chymotrypsin으로 분해한 lactoferrin은 분해되지 않은 lactoferrin이 존재함을 나타내고, 33KDa에서도 band를 확인할 수 있었다. 2. Sephadex G-50 column을 사용하여 bovine lactoferrin를 효과적으로 정제하였다. Sephadex G-50 column chromatography를 수행 한 결과 bovine lactoferrin은 Tris-HCl사이에서 용출되었으며, pepsin, trypsin 및 chymotrypsin으로 분해한 lactoferrin은 각각 2, 3, 2 개의 peak를 보였고, HPLC 분석결과 첫번째 peak는 주로 분해되지 않은 lactoferrin 수용체가 존재하는 것으로 확인되었으며, trypsin과 chymotrypsin처리에서 항균효과도 유사점을 관찰할 수 있었다. 3. 효소처리한 lactoferrin의 항균효과를 알아보기 위하여 Escherichia coli와 Staphylococcus aureus를 접종하여 항균활성을 비교하였다. 그 결과 각 효소에 대하여 pepsin으로 처리한 lactoferrin을 접종한 시험구가 대조구에 비하여 낮은 생장율을 보여 현저한 항균활성을 지님을 알 수 있었다. 그리고 trypsin과 chymotrysin에 의한 분해물도 미생물 배양 8시간까지는 효소 처리전 bovine lactoferrin보다는 항균활성을 나타냄을 알 수 있었다. 4. Sephadex G-50 column을 사용하여 분리 정제된 bovine lactoferrin fraction별로 SDS-PAGE를 실시한 결과 lactoferrin fraction의 경우는 chromatography 수행 결과와 비교하여, pepsin과 chymotrypsin 분해물은 저분자량임을 알 수 있었고, trypsin에 의한 lactoferrin만이 단일 band를 보임으로서 단백질 분해의 특징을 볼 수 있었다.