title: Characterization of bioactive recombinant human lysozyme expressed in milk of cloned transgenic cattle.
abstract: BACKGROUND
  There is great potential for using transgenic technology to improve the quality of cow milk and to produce biopharmaceuticals within the mammary gland. Lysozyme, a bactericidal protein that protects human infants from microbial infections, is highly expressed in human milk but is found in only trace amounts in cow milk.
  
  
  RESULTS
  We have produced 17 healthy cloned cattle expressing recombinant human lysozyme using somatic cell nuclear transfer. In this study, we just focus on four transgenic cattle which were natural lactation. The expression level of the recombinant lysozyme was up to 25.96 mg/L, as measured by radioimmunoassay. Purified recombinant human lysozyme showed the same physicochemical properties, such as molecular mass and bacterial lysis, as its natural counterpart. Moreover, both recombinant and natural lysozyme had similar conditions for reactivity as well as for pH and temperature stability during in vitro simulations. The gross composition of transgenic and non-transgenic milk, including levels of lactose, total protein, total fat, and total solids were not found significant differences.
  
  
  CONCLUSIONS
  Thus, our study not only describes transgenic cattle whose milk offers the similar nutritional benefits as human milk but also reports techniques that could be further refined for production of active human lysozyme on a large scale.
authors: State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, People's Republic of China.
authors: Bin
authors: B
authors: Yang
authors: Jianwu
authors: J
authors: Wang
authors: Bo
authors: B
authors: Tang
authors: Yufang
authors: Y
authors: Liu
authors: Chengdong
authors: C
authors: Guo
authors: Penghua
authors: P
authors: Yang
authors: Tian
authors: T
authors: Yu
authors: Rong
authors: R
authors: Li
authors: Jianmin
authors: J
authors: Zhao
authors: Lei
authors: L
authors: Zhang
authors: Yunping
authors: Y
authors: Dai
authors: Ning
authors: N
authors: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002417:Cattle; D002852:Chromatography, Ion Exchange; D019976:Cloning, Organism; D004795:Enzyme Stability / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008837:Micrococcus / Q000187:drug effects; D008892:Milk / Q000187:drug effects / Q000201:enzymology*; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D009391:Nephelometry and Turbidimetry; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; C421864:hen egg lysozyme; D009113:Muramidase