Abstract
Bovine k-casein macropeptide was prepared by adding TCA (3, 6, and $12\%$) treatment after chymosin reaction. Each TCA soluble macropeptide was fractionated into five peak by ion exchange column chromatography. In proportiion to TCA concentrations, the ratio of peak area showed different the elution pattern. At the 6 and $12\%$ TCA concentration, area ratio of P-I which did not content carbohydrates was decreased to 19.9 and $17.0\%$ of total peak area respectively. The area of P-III was changed from $10.2\%\;to\;26.2\;and\;13.2\%$ when the TCA concentration was increased from 3 to 6 and $12\%$ Cholera toxin binding activity of k-casein macropeptide eluted at $0.17\~0.18M$ NaCl gradient was not inhibited by 6 and $12\%$ TCA treatments. The use of $6\%$ TCA as extraction buffer was feasible and led to an effective separation of the peak III.
k-Casein을 정제한 후 여기에 chymosin을 반응시켜 얻어진 k-Casein macropeptide에 대한 trichloroacetic acid 처리에 대한 영향을 조사하고자 ion exchange column으로 분별하여 chromatogram을 비교하였다. P-I의 경우 $3\%$ TCA에서는 전체 peak면적 대비 $46.64\%$이었으나, $6\%$와 $12\%$ TCA로 영향을 크게 받아 많이 침전되었으며, 상대적으로 당 함량이 높은 peak들은 TCA의 영향을 비교적 적게 받는 것으로 나타났다. Cholera 독소와 결합하는 것으로 보고된 P-III는 $3\%$ TCA에서는 $10.2\%$이었으나 $6\%$ TCA 경우에는 $26.3\%$로 상대적 면적이 증가하였으나 $12\%$ TCA로 처리한 경우에는 $13.2\%$로 감소하였다. $0.2\~0.3M$의 NaCl에서 용출되는 peak는 $12\%$ TCA에서도 상당한 안정성을 보였다. 0.18M의 NaCl gradient에서 용출되는 P-III는 $6\%$및 $12\%$ TCA처리시에도 cholera 독소와 반응하는 것으로 나타났다.
