• 한국식품과학회지
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• 제25권5호
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• pp.521-525
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• 1993

계면에서의 단백질 흡착 기작을 연구하기 위하여 여러 단백질의 A/W 계면에서의 흡착이 조사되었다. BSA intermediates들의 흡착결과는 단백질 2차, 3차 구조가 계면에서의 흡착기작에 영향끼친 것을 나타냈으며, succinylated ${\beta}-lactoglobulin$의 흡착에서는 순 음전하의 증가가 정전기적 상호작용에 영향끼침을 보여 주었다. 또한 ${\beta}-casein$의 흡착은 물 구조를 파괴하는 chaotropic 염 존재하에서 흡착속도가 떨어지는 것을 시사했다.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.685-693
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• 1996

A total of 3,610 Ayrshire and 1,711 Jersey cows were phenotyped for the genetic variants of ${\alpha}_{s1}$-casein, ${\beta}$-casein, $\chi$-casein, ${\beta}$-lactoglobulin and ${\alpha}$-lactalbumin. Least squares analyses showed possible associations between milk protein phenotypes and lactational production traits. Depending on lactation number, ${\beta}$-casein phenotypes in Ayrshires were associated with milk production ($A^2A^2$ > $A^1A^2$ > $A^1A^1$), and with milk protein content. In the third lactation, Ayrshire cows with ${\beta}$-casein $A^1A^1$ produced milk with 3.43% fat compared to 3.37% fat for ${\beta}$-casein $A^2A^2$. In Ayrshire, $\chi$-casein phenotypes affected the protein content during the three lactations (BB > AB > AA) and ${\beta}$-lactoglobulin phenotypes significantly influenced the milk fat during the first lactation (4.06% for AA and 3.97% for BB). In Jerseys, protein content of milk was influenced by phenotypes of ${\alpha}_{s1}$-casein(3.98% for CC v/s 3.86% for BB in the first lactation). In the third lactation, $\chi$-casein AA of Jersey milk contained 5.35% fat compared to 4.82% for phenotype BB. The effects of ${\beta}$-lactoglobulin phenotypes on protein content were apparent in Jerseys during the second lactation with the A variant being superior to the B (4.00% for AA v/s 3.87% for BB).

• BMB Reports
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• 제33권2호
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• pp.133-137
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• 2000

To elucidate the effect of oxygen radicals on the molecular properties of proteins, the secondary and tertiary structure and molecular weight size of BSA and ${\beta}$-lactoglobulin were examined after irradiation of proteins at various doses. Gamma-irradiation of protein solutions caused the disruption of the ordered structure of protein molecules as well as degradation, cross-linking, and aggregation of the polypeptide chains. As a model system, BSA and ${\beta}$-lactoglobulin were used as a typical ${\alpha}$-helical and a ${\beta}$-sheet structure protein, respectively. A circular dichroism study showed that the increase of radiation decreased the ordered structure of proteins with a concurrent increase of aperiodic structure content. Fluorescence spectroscopy indicated that irradiation quenched the emission intensity excited at 280 nm. SDS-PAGE and a gel permeation chromatography study indicated that radiation caused initial fragmentation of proteins resulting in a subsequent aggregation due to cross-linking of protein molecules.

• Journal of Animal Science and Technology
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• 제44권6호
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• pp.801-808
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• 2002

상업적 단백질 분해 효소에 0.02% $CaCl_2$를 첨가하여 응유 활성화를 시킨 탈지유에 대한 분해 작용의 결과를 요약하면 다음과 같다. 다양한 효소별 가수분해 시간에 따른 가수분해도는 미생물 유래 효소와 trypsin은 pepsin과 papain W-40보다 높은 분해도를 나타냈다. 12% TCA 용액에 가용성인 NPN의 양은 trypsin이 가장 높은 분해도를 나타내었고 rennet과 pepsin이 가장 낮은 분해도를 보였다. 전기영동에 있어서 trypsin과 protease S는 $\alpha$- lactalbumin을 분해하였고 papain w-40은 $\beta$- lactoglobulin을 미약하게 분해하였으며 neutrase 1.5는 90분 이후부터 $\alpha$-lactalbumin과 $\beta$-lactoglobulin을 분해하였다. Rennet과 비교한 전기영동상에서는 rennet에 의해 분해 되지 않은 ${\alpha}_s$- casein과 $\beta$-casein을 trypsin과 protease S가 다량 분해하였고 $\kappa$-casein은 rennet에 비해 papain W-40이 상당 수준의 분해상을 나타내었다. 이상의 결과 가수분해도 및 NPN 양은 trypsin, neutrase 1.5 및 protease S가 다른 효소에 비해 높게 나타났으며, 전기영동상에서는 pepsin과 neutrase 1.5가 rennet과 유사한 경향을 나타내었다.

• 한국응용과학기술학회지
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• 제17권3호
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• pp.158-166
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• 2000

A conductimetric study of foam formed from mixture of the protein, ${\beta}-lactoglobulin$, and the nonioinc surfactant, SML, revealed that their stability was reduced at concentrations of SML in the range $3{\sim}10mM$. The interaction of SML with ${\beta}-lactoglobulin$ was investigated by fluorimetry and a dissociation constant of $0.2{\mu}M$ was calculated for the complex. Surface tension studies confirmed the presence of interaction between the two components and provided evidence for the progressive displacement of ${\beta}-lactogloblin$ from the air/water interface with increasing SML concentration. Experiments using air-suspended microscopic thin liquid films revealed transitions in the chainage characteristics and thickness of the film at SML concentrations below that which resulted in destabilization of the foam. However, measurements of surface mobility of fluorescent-labeled ${\beta}-lactoglobulin$ by a photobleaching method identified that a transition to a mobile system occurred at a SML concentration which correlated with the onset of instability in the disperse phase. The results would indicate that maintenance of the viscoelastic properties of the surface is paramount importance in determining the stability of interfaces comprising mixtures of protein and surfactant.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1212-1217
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• 2003

Fifty-two Holstein cows with different phenotypes of $\kappa$-casein ($\kappa$-CN) and $\beta$-lactoglobulin ($\beta$-LG) were selected to provide weekly milk samples for heating at 30, 70, 75 and $80^{\circ}C$ for 2 min. Coagulating properties of heated milk samples measured as rennet clotting time, rate of curd firming and curd firmness at cutting were determined by a Formagraph. Milk samples were analysed for fat and casein. Least squares analyses of data, after adjustments were made for effect of milk casein and fat contents, indicated that although an increase in heating temperatures resulted in less desirable coagulating properties, the effect of milk types was inherent irrespective of heating temperatures. The shortest rennet clotting time (6.06 min), fastest rate of curd firming (5.61 min) and firmest curd (38.05 mm) were obtained from milk with the B variant for $\kappa$-CN and B variant for $\beta$ -LG when preheated at $30^{\circ}C$. It appears that milk bearing $\kappa$-CN B is more resistant to heat perturbation. All milk samples having the $\kappa$-casein AA (milk types AA/AA, AA/AB, AA/BB) did not have a measurable K20 value when preheated at $70^{\circ}C$. This effect was observed for $\kappa$-casein AB (milk types AB/AA, AB/AB, AB/BB) at $75^{\circ}C$ and $\kappa$-casein BB (milk types BB/AA, BB/AB, BB/BB) at $80^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• 제15권5호
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• pp.732-739
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• 2002

Milk samples with different phenotype combination of $\{kappa}$-casein and ${\beta}$-lactoglobulin and different preheating temperatures of 30, 70, 75 and $80^{\circ}C$ were used for cheesemaking under laboratory conditions. For the 853 batches of cheese, mean composition was 59.64% total solids, 30.24% fat and 23.66% protein, and the whey contained 6.93% total solids, 0.30% fat and 0.87% protein. Least squares analysis of the data indicated that heating temperature of the milk and ${\kappa}$-CN/${\beta}$-LG phenotypes had significant effects on cheese and whey compositions. The total solids, fat and protein contents of cheese were negatively correlated with preheating temperatures of milk. Cheese from BB/BB phenotype milk had the highest and those from AA/AA phenotype milk had the lowest concentrations of total solids, fat and protein. Mean recoveries of milk components in the cheese were 53.71% of total solids, 87.15% of fat, and 80.32% of protein. For the 10 different types of milk, maximum recoveries of milk components in cheese occurred with preheating temperature of $70^{\circ}C$ or $75^{\circ}C$ and lowest recoveries occurred at $80^{\circ}C$. The whey averaged 6.94% total solids, 0.30% fat and 0.87% protein. Losses of milk components in the whey were lowest for milk preheated at $80^{\circ}C$ and for milk containing the BB/BB phenotype.

• 한국식품과학회지
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• 제19권4호
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• pp.285-289
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• 1987

Poly(ethylene glycol)과 인산염 용액(PPB)이 형성 하는 액상 이상계에서 단백질의 분획 거동을 관찰하였다. PEG(12%)/PPB(12%) 액상 이상계에서 단백질의 표면 소수성이 다른 BSA, ${\beta}-lactoglobulin$, ovalbumin 모두 PPB-rich phase인 하층부로 몰려 그 분획계수는 대단히 낮았다. PPB의 농도를 15%로 증가 시키면 하층부의 전위는 +50mV 에서 0으로 낮아져 단백질의 분획계수가 다소 증가하는 경향을 나타내었다. PPB의 제2인산염과 제일인산염의 몰 비율을 1.43에서 9.55로 증가시키면 이상계의 상 하층부 부피비(Vt/Vb)가 다소 감소되면서 분획계수는 증가하였다. PPB농도를 $14{\sim}26%$로 증가시키면 이상계의 부피비는 1.5에서 0.39로 현저히 감소하면서 단백질의 분획계수는 ${\beta}-lactoglobalin$의 경우 74배, BSA 32배, ovalbumin 12배, lysozyme 5배로 크게 증가하였다.

• Animal cells and systems
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• 제1권2호
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• pp.345-350
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• 1997

The ${\beta}$-Lactoglobulin (BLG) gene expression is differentially regulated during development of the mammary tissues. Such differential regulation of the BLG gene expression can be reiterated in the cultured mammary HC11 cells. In the growing non-confluent HC11 cells, the BLG promoter activity was shown to be partially repressed by the upstream regulatory sequence. The repression was gradually diminished and switched to activation as the cells grew confluent. The differential regulation of the BLG promoter was controlled by the 5'-regulatory sequence located at the upstream of 205 bp. Electromobility shift assay showed that nuclear extract from HC11 cells differentially bound on the regulatory sequence, depending on the cell confluency, which was in accordance with the differential transcriptional activity. DNase I foot-print assay, however, revealed that all nuclear extracts presented the same foot-prints, regardless of confluency of HC11 cells. These results suggest that differential regulation BLG gene expression by the 5'-regulatory sequence may be accomplished by competitive and/or cooperative binding of differential regulatory factors on the same regulatory element.

• Asian-Australasian Journal of Animal Sciences
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• 제15권3호
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• pp.326-329
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• 2002

A population of exotic Holstein Friesian, Jersey, their crossbreds and the indigenous Murrah breed of buffalo bulls (n=486), used in artificial insemination breeding program were screened for the allelic distribution of the ${\kappa}$-casein and ${\beta}$-lactoglobulin genotypes. The preferred "B" allele frequency was highest in Murrah buffalo bulls followed by Jersey and Holstein Friesian. The increase in this particular allele frequency in the Holstein Friesian crossbred bulls was more when compared to their Jersey counterparts. Hardy-Weinberg's equilibrium was maintained albeit with some deviations, which was higher in crossbreds than in purebreds. The feasibility of using such large-scale molecular diagnostic tools in the field and their significance with regards to the dairy economy is discussed.