• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.783-792
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• 2014

The binding interaction between a hemolytic peptide ${\delta}$-lysin and a zwitterionic lipid bilayer POPC was investigated through a series of molecular dynamics (MD) simulations. ${\delta}$-Lysin is a 26-residue, amphipathic, ${\alpha}$-helical peptide toxin secreted by Staphylococcus aureus. Unlike typical antimicrobial peptides, ${\delta}$-lysin has no net charge and it is often found in aggregated forms in solution even at low concentration. Our study showed that only the monomer, not dimer, inserts into the bilayer interior. The monomer is preferentially attracted toward the membrane with its hydrophilic side facing the bilayer surface. However, peptide insertion requires the opposite orientation where the hydrophobic side of peptide points toward the membrane interior. Such orientation allows the charged residues, Lys and Asp, to have stable salt bridges with the lipid head-group while the hydrophobic residues are buried deeper in the hydrophobic lipid interior. Our simulations suggest that breaking these salt bridges is the key step for the monomer to be fully inserted into the center of lipid bilayer and, possibly, to translocate across the membrane.

• Korean Journal of Veterinary Research
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• v.22 no.1
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• pp.15-21
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• 1982

The biochemical properties of strains of Staphylococcus aureus isolated from cattle with peracute gangrenous mastitis, acute systemic mastitis and chronic mastitis were examined. Of 261 strains of Staphylococci isolated from quarters with clinical mastitis, 140 (53.6%) were classified as Staphylococcus aureus and 121 (46.4%) were coagulase-negative staphylococci. All the strains of Staphylococcus aureus isolated from quarters with peracute gangrenous mastitis and acute systemic mastitis showed production of alpha heamolysin, coagulase, lipase, phosphatase, nuclease and gelatinase, and fermentation of mannitol. However, of 114 strains of Staphylococcus aureus obtained from quarters with chronic mastitis, 64 (56.1%) possessed alpha lysin, and 43 (37.7%) produced lipase in egg yolk medium. The most common hemolytic pattern of the strains associated with chronic mastitis was ${\beta}{\delta}$ type.

• The Korean Journal of Community Living Science
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• v.18 no.4
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• pp.715-724
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• 2007

홍화 (Carthamus tinctorius)는 오래 전부터 각종 감염성 질환이나 암을 치료하는데 효과가 있는 것으로 알려져 왔다. 최근 각종 천연산물에 사람과 동물의 건강을 증진시키는 효과가 있는 것이 밝혀지면서, 홍화의 면역조절 효과에 대한 관심이 높아지고 있으나 이에 대한 과학적 자료가 부족한 실정이다. 따라서, 본 연구는 홍화의 면역 조절 활성을 확인하기 위해 수행되었으며, 면역능 실험을 위해 주로 이용되는 실험용 닭(White Leghorn chickens)에게 홍화잎을 첨가한 실험식이를 3주간 급여한 후 관련 요인들을 분석하였다. 실험 결과, 홍화잎을 섭취한 실험동물에서 비장 면역세포의 증식이 많았고, $Y{\delta}$-TCR+ 세포의 비율이 높아졌으며, 십이지장에서는 IFN-Y, IL-8, IL-10, IL-15 및 NK-lysin 같은 사이토카인의 발현이 높아졌다. 따라서, 홍화잎은 식이와 함께 급여하였을 때 면역 증강 효과가 있는 것으로 밝혀졌으며, 홍화잎을 이용한 각종 제품 개발이 기대된다.