Abstract
Carboxypeptidase B from Salmo Salar eggs was purified by CM-cellulose, 0.5 ammonium sulfate saturation, DEAE-cellulose, and Sephadex G-75 gel filtration and its enzymatic properties were investigated. Optimum temperature was 55$^{\circ}C$, pH optima were 4.0 and 7.0 at 37$^{\circ}C$, and the enzyme was stable at pH 2.0∼3.0 and 5.5∼7.0 for 1.5h. This enzyme showed substrate specificity hydrolyzing the peptide bond of glycyl-L-arginine. Its K$_m$ values was 0.21mM, and the enzyme activity was stimulated by Cu$^{2+}$ and Fe$^{3+}$, while inhibited by Zn$^{2+}$. The lysine was found to be competitive inhibitor and its K$_i$ value was determined to be 4.3mM. Molecular weight of this enzyme was determined to be 36,400 daltons by SDS-PAGE and the enzyme was monomeric protein composed of 19 kinds of amino acid residues.
연어(Salmo Salar)알 중의 Carboxypeptidase B를 CM-셀룰로오스, 0.5포화황산 암모늄, DEAE-셀룰로오스 및 세파덱스 G-75젤로 정제하여 그 성질을 조사하였다. 이 효소의 최적 온도는 55$^{\circ}C$였으며, 최적 pH는 4.0과 7.0이었고, pH안정성은 2.0∼3.0 및 5.5∼7.0이었다. 히푸릴-L-아르기닌 기질에 대하여 글리실-L-아르기닌 부위를 절단하는 특이성을 보였고, 그 K$_m$값은 0.21mM이었다. Cu$^{2+}$ 와 Fe$^{3+}$ 존재하에서는 효소의 활성도가 증가하였지만 Zn$^{2+}$의 경우에는 감소하였다. 특히 리신은 히푸릴-L-아르기닌 기질에 대하여 경쟁적 억제작용을 보였으며, K$_i$값은 4.3mM이었다. 분자량은 36,400돌톤이었고, 19종류의 아미노산으로 구성된 단위체이었다.