• 한국축산식품학회지
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• 제37권6호
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• pp.940-947
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• 2017

Goat milk has a protein composition similar to that of breast milk and contains abundant nutrients, but its use in functional foods is rather limited in comparison to milk from other sources. The aim of this study was to prepare a goat A2 ${\beta}$-casein fraction with improved digestibility and hypoallergenic properties. We investigated the optimal conditions for the separation of A2 ${\beta}$-casein fraction from goat milk by pH adjustment to pH 4.4 and treating the casein suspension with calcium chloride (0.05 M for 1 h at $25^{\circ}C$). Selective reduction of ${\beta}$- lactoglobulin and ${\alpha}_s$-casein was confirmed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography. The hypoallergenic property of A2 ${\beta}$-casein fraction was examined by measuring the release of histamine and tumor necrosis factor alpha from HMC-1 human mast cells exposed to different proteins, including A2 ${\beta}$-casein fraction. There was no significant difference in levels of both indicators between A2 ${\beta}$-casein treatment and the control (no protein treatment). The A2 ${\beta}$-casein fraction is abundant in essential amino acids, especially, branched-chain amino acids (leucine, valine, and isoleucine). The physicochemical properties of A2 ${\beta}$-casein fraction, including protein solubility and viscosity, are similar to those of bovine whole casein which is widely used as a protein source in various foods. Therefore, the goat A2 ${\beta}$-casein fraction may be useful as a food material with good digestibility and hypoallergenic properties for infants, the elderly, and people with metabolic disorders.

• 한국축산식품학회지
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• 제25권2호
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• pp.238-243
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• 2005

산양유 $\beta-casein$의 효소에 의한 가수분해 특성과 가수분해물의 ACE 저해 효과를 측정하고자 산양유의 $\beta-casein$을 양이온 교환 컬럼인 Mono S HR 5/5를 이용하여 분리하였으며 분리된 $\beta-casein$을 동물성 분해효소인 trypsin으로 처리하여 가수분해 특성을 확인하였고 가수분해물의 ACE 저해활성을 측정하였다. Mono S HR 5/5 양이온 교환 컬럼을 이용한 산양유 산 케이신으로 부터 순수한 $\beta-casein$의 분리는 SDS-PAGE를 이용하여 확인한 결과 순수한 $\beta-casein$의 분리가 이루어졌음을 확인할 수 있었다. $\beta-casein$을 $37^{\circ}C4$에서 trypsin으로 처리하여 전기영동으로 확인한 결과 가수분해 직후부터 $\beta-casein$ 위치의 band가 희미해지기 시작하고 저분자량의 band가 나타나기 시작하였으나 120분이 지난 후에는 모든 band가 가수분해되어 사라졌고 산양유에서 분리된 $\beta-casein$을 trypsin으로 처리하여 120분 경과 후 그 가수분해물을 이용하여 ACE 저해효과를 측정한 결과 가수분해하지 않은 $\beta-casein$은 $1.80\pm1.21\%$의 ACE 저해활성을 보였으나 trypsin으로 가수분해하여 ACE 저해 활성을 측정하였을 때 $25.36\pm0.79\%$의 저해 활성을 나타내었으며, trypsin에 의한 $\beta-casein$가수분해물의 $IC_{50}$을 측정한 결과 $308.7\pm2.77({\mu}g/mL)$로 나타났다.

• 농업과학연구
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• 제29권2호
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• pp.43-52
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• 2002

본 연구는 한국 재래 산양 112두와 유산양인 Saanen종 7두의 혈액으로부터 genomic DNA를 추출하고, PCR-RFLP 방법에 의해 $\beta$-casein 유전자의 특성을 분석하여 한국재래산양의 효율적인 유전자원의 보존 및 개량을 위한 기초 자료로 제공하고자 실시하였다. 한국재래산양의 genomic DNA로부터 PCR기법을 이용하여 $\beta$-casein의 유전자좌를 증폭한 결과 각각 481bp 크기의 단편이 양호하게 증폭되었음을 확인하였다. $\beta$-casein 유전자 좌의 증폭산물에 대한 Bal I의 제한효소를 처리한 결과, $\beta$-casein AB형은 481bp, 284bp 및 197bp의 단편을, 그리고 BB형은 284bp와 197bp의 단편을 한국재래산양과 유산양인 Saanen 종에서 확인 할 수 있었다. 유전자형 빈도에 있어서는 한국재래산양에서 $\beta$-casein AB 및 BB의 빈도는 각각 6.25 및 93.75%이었고, 유산양인 Saanen 종은 각각 57.14 및 42.86%이었다. 유전자빈도에 있어서는 한국재래산양의 $\beta$-casein A 및 B의 빈도가 각각 0.031 및 0.969이었고, Saanen 종에서는 각각 0.286 및 0.714의 빈도를 보였다. 한국재래산양의 $\beta$-casein 유전자의 염기서열과 이미 보고되어 있는 goat의 염기서열(GeneBank accession Number M90556)간에는 총 11개의 염기서열에 차이를 나타내어 97.71%의 상동성을 보였다. 따라서 한국재래산양의 $\beta$-casein 유전자의 다형성과 염기서열 분석에 의한 분자유전학적 특성의 규명은 한국재래산양의 유전자원의 보존 및 개량을 위한 기초 및 응용 자료로 이용될 수 있을 것으로 생각된다.

• Reproductive and Developmental Biology
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• 제30권4호
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• pp.293-299
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• 2006

In order to generate transgenic goats expressing human growth hormone (hGH) in their mammary glands, goat ${\beta}-Casein/hGH$ hybrid gene was introduced into goat zygotes by pronuclear microinjection. DNA-injected embryos were transferred to the oviduct of recipients at 2-cell stage or to the uterus at morula/blastocyst stage after cultivation in glutathione-supplemented mSOF medium in vitro. Pregnancy and survival rate were not significantly different between 2-cell embryos and morula/blastocysts transferred to oviduct and uterus, respectively. One transgenic female goat was generated from 153 embryos survived from DNA injection. Southern blot analysis revealed that the transgenic goat harbored single-copy transgene with a partial deletion in its sequences. Despite of the partial sequence deletion, the transgene was successfully expressed hGH at the level of $72.1{\pm}15.1{\mu}g/ml$ in milk throughout lactation period, suggesting that the sequence deletion had occurred in non-essential part of the transgene for the transgene expression. Unfortunately, however, the transgene was not transmitted to her offspring during three successive breeding seasons. These results demonstrated that goat ${\beta}-casein/hGH$ gene was integrated into the transgenic goat genome in a mosaic fashion with a partial sequence deletion, which could result in a low level expression of hGH and a failure of transgene transmission.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.421-427
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• 2012

The production of therapeutic proteins from transgenic animals is one of the most important successes of animal biotechnology. Milk is presently the most mature system for production of therapeutic proteins from a transgenic animal. Specifically, ${\beta}$-casein is a major component of cow, goat and sheep milk, and its promoter has been used to regulate the expression of transgenic genes in the mammary gland of transgenic animals. Here, we cloned the porcine ${\beta}$-casein gene and analyzed the transcriptional activity of the promoter and intron 1 region of the porcine ${\beta}$-casein gene. Sequence inspection of the 5'-flanking region revealed potential DNA elements including SRY, CdxA, AML-a, GATA-3, GATA-1 and C/EBP ${\beta}$. In addition, the first intron of the porcine ${\beta}$-casein gene contained the transcriptional enhancers Oct-1, SRY, YY1, C/EBP ${\beta}$, and AP-1, as well as the retroviral TATA box. We estimated the transcriptional activity for the 5'-proximal region with or without intron 1 of the porcine ${\beta}$-casein gene in HC11 cells stimulated with lactogenic hormones. High transcriptional activity was obtained for the 5'-proximal region with intron 1 of the porcine ${\beta}$-casein gene. The ${\beta}$-casein gene containing the mutant TATA box (CATAAAA) was also cloned from another individual pig. Promoter activity of the luciferase vector containing the mutant TATA box was weaker than the same vector containing the normal TATA box. Taken together, these findings suggest that the transcription of porcine ${\beta}$-casein gene is regulated by lactogenic hormone via intron 1 and promoter containing a mutant TATA box (CATAAAA) has poor porcine ${\beta}$-casein gene activity.

• Asian-Australasian Journal of Animal Sciences
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• 제17권6호
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• pp.743-749
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• 2004

The gene encoding human serum albumin (HSA) was cloned from human liver cDNA library by PCR. The HSA cDNA in size of 2,176 bp, including 1,830 bp of open reading frame, was cloned into the plasmid carried with the 5'flanking sequence of goat $\beta$-casein gene (-4,044 to +2,025 bp) to get a tissue specific expression vector in mammary gland named pGB562/HSA (12.5 kb). A 9.6 kb DNA fragment in which the sequence is in order of goat $\beta$-casein gene regulatory sequence, HSA cDNA and SV40 polyadenylation signals was isolated from the pGB562/HSA by SacI and DraIII cutting, and used to microinject into the pronuclei of mouse fertilized eggs to produce transgenic mice. Three transgenic mice (2 female and 1 male) were identified by PCR and dot Southern blot analysis. The copy numbers of integrated transgene were more than 10 copies in line #21 and #26 as well as over 50 copies in line #31 of transgenic mice. HSA protein collected from the milk of lactating transgenic mice was confirmed by immuno-detection of Western and slot blot. The concentrations of HSA in the milk were from 0.05 to 0.4 mg/ml. An obvious antigen and antibody conjugate could be observed in immunohistochemical stain of mammary gland tissue from lactating day 11 of HSA transgenic mice. The transmission of transgene and its expression was recognized according to the results of RT-PCR and sequences analyses of their progeny.

• 한국발생생물학회지:발생과생식
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• 제17권1호
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• pp.1-8
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• 2013

Osteoprotegerin (OPG) is a secreted glycoprotein that regulates bone resorption by inhibiting differentiation and activation of osteoclast, thereby potentially useful for the treatment of many bone diseases associated with increased bone loss. In this study, we designed a novel cDNA expression cassette by modifying the potent and mammary gland-specific goat ${\beta}$-casein/hGH hybrid gene construct and examined human OPG (hOPG) cDNA expression in transgenic mice. Six transgenic mice all successfully expressed hOPG in their milk at the level of 0.06-2,000 ${\mu}g/ml$. An estimated molecular weight of the milk hOPG was 55 kDa in SDS-PAGE, which is the same as a naturally glycosylated monomer. This hOPG expression was highly specific to the mammary glands of transgenic mice. hOPG mRNA was not detected in any organs analyzed except mammary gland. Functional integrity of milk hOPG was evaluated by TRAP (tartrate-resistant acid phosphatase) activity assay in bone marrow cell cultures. OPG ligand (OPG-L) treatment increased TRAP activity by two fold but it was completely abolished by co-treatment with transgenic milk containing hOPG. Taken together, our novel cDNA expression cassette could direct an efficient expression of biologically active hOPG, a potential candidate pharmaceutical for bone diseases, only in the mammary gland of transgenic mice.

• Asian-Australasian Journal of Animal Sciences
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• 제22권2호
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• pp.168-173
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• 2009

Human follicle-stimulating hormone (hFSH) is a pituitary glycoprotein that regulates follicular development and ovulation. Clinically, hFSH has been used to induce follicular growth in infertile women. The hormone is composed of heterodimers, including a common ${\alpha}$ subunit among the gonadotropin family and a hormone-specific ${\beta}$ subunit. Since assembly of the heterodimer is a rate-limiting step in the production of functional hFSH, transgenic clone cows carrying a single-chain hFSH transgene may efficiently produce functional hormone. Genes encoding the ${\alpha}$ and ${\beta}$ subunits of hFSH were linked using the C-terminal peptide sequence from the ${\beta}$ subunit of human chorionic gonadotropin. Bovine fetal fibroblasts were transfected with the gene construct, including the goat ${\beta}$-casein promoter and a single-chain hFSH coding sequence. Transfected fibroblasts were transferred into enucleated oocytes, and individual nuclear transfer (NT) embryos developed to the blastocyst stage were analyzed for the transgene by polymerase chain reaction. Seventy eight blastocysts (30.8%) were developed from 259 reconstructed embryos. Among these blastocysts, the hFSH gene was detected in 70.8% (34/48) of the embryos. Subsequent transfer of hFSH-transgenic clone embryos to 31 recipients results in 11 (35.5%) early pregnancies. However, all fetuses were lost before reaching day 180 of gestation. The results from this study demonstrated that bovine NT embryos carrying single-chain hFSH could be produced, and further extensive studies in which NT embryos are transferred to more recipients may give rise to single chain hFSH-transgenic cows for biomedical applications.

• 한국식품과학회지
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• 제46권2호
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• pp.121-126
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• 2014

산양유는 단백질 구성과 개별 지방산의 구성이 모유에 가깝기 때문에 우유에 비하여 소화율이 높다. 특히 casein 단백질은 모유의 단백질과 분자구조가 흡사하여 높은 소화 흡수력을 보이므로 설사 또는 복통 등과 같은 소화장애를 일으키지 않는다. 뿐만 아니라 지방산 함량에 있어서도 우유보다 중간사슬지방산이 우유보다 2배정도 많이 들어있어 소화 흡수 시 분해되는 속도가 빠르다. 산양유에는 질 좋은 수용성 유청단백질, 비타민 및 미네랄이 다량 함유되어 있고, 특히 비타민 A, 콜린, 이노시톨의 함량이 높고 흡수율도 양호한 편이다. 산양유에 포함된 유당과 올리고당은 우유보다 모유에 더 가까운 효과를 기대할 수 있다. 유당은 장 내 산성을 증가시켜 유익한 박테리아의 증식을 돕는 한편 장내에서의 칼슘의 흡수를 도와주거나 인(P)과 마그네슘(Mg)의 흡수를 촉진시키는 역할을 담당한다. 또한 올리고당류는 장내유산균의 생육을 돕는 prebiotic 효과를 발휘하여 장내 유익균이 정착하는데 도움을 준다는 실험결과로 판단할 때 실제로 유아에게 정장작용을 기대할 수 있다. 그리고 산양유에 다량 함유된 미네랄 성분 또한 소화 및 흡수를 촉진시키는 역할을 하기 때문에 산양유는 우유 섭취 시 유당불 내증을 호소하던 소비자들도 어렵지 않게 섭취할 수 있다. 이처럼 산양유가 여러 가지 측면에서 우유보다 우수한 식품학적 생리적 특성을 가지고 있음에도 불구하고 국내 산양유가공 산업은 거의 불모지라 해도 과언이 아니다. 게다가 산양유의 정확한 영양학적 가치가 일반 소비자들에게 전달되지 못하고 있는 실정이다. 따라서 우유보다 그 성분과 조성이 모유와 흡사한 산양유의 식품학적 특성, 안전성 및 기능성에 대한 체계적이며 과학적 연구가 시급히 활성화되어야 할 것이다.