TRANSAMINASE ACTIVITY IN HUMAN BLOOD
TRANSAMINASE ACTIVITY IN HUMAN BLOOD
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DOI：
10.1172/jci103055
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发表时间：
1955-01-01
影响因子：
15.9
通讯作者：
LADUE, JS
中科院分区：
文献类型：
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作者：
KARMEN, A;WROBLEWSKI, F;LADUE, JS
ARTHUR KARMEN， FELIX WR6BLSWSKI和JOHN S. LADUE也同样被发现不影响血清转氨酶活性。在给定的血清培养混合物中，天冬氨酸浓度的增加比α -酮戊二酸浓度的增加更能引起谷氨酸产生率的增加，这表明在这些浓度下酶与底物的完全饱和尚未实现。这些结果与报道的猪心肌转氨酶制剂基本一致（7,8）。通过改变所用缓冲液的组成，研究了pH值对血清转氨酶活性的影响。用不同pH值的0.2 M磷酸盐缓冲液代替0.06 M缓冲液。测定孵育前后各孵育液的pH值。孵育后，每个样品的pH值从0.1增加到0.2 pH单位，孵育前后的平均值作为混合物的pH值。在pH 7.0和8.0之间的最大活性（图3）与Cohen(9)等人使用猪心肌作为转氨酶来源的结果基本一致。血清样品在室温下保存10分钟至96小时，或在冰箱（0℃至5℃）中保存1小时至2周，转氨酶活性未见随时间变化。冷冻或冻干对转氨酶活性没有影响
ARTHUR KARMEN, FELIX WR6BLSWSKI, AND JOHN S. LADUE was similarly found not to affect the observed transaminase activity of serum. Increased concentration of aspartate in a given serum incubation mixture was seen to cause a greater increase in the observed rate of glutamate production than an increase in the concentration of alpha-keto glutarate, demonstrating that complete saturation of the enzyme with substrate had not been achieved at these concentrations. These results are in essential agreement with those re-ported for transaminase preparations from pig heart muscle (7, 8).The effect of pH on serum transaminase ac-tivity was studied by altering the composition of the buffer used. Phosphate buffer, 0.2 M, of several pH values was substituted for the 0.06 M buffer. The pH of each incubation mixture was determined before and after incubation. An increase in pH from 0.1 to 0.2 pH units was ob-served in each sample after the incubation period and the average of the pre-and post-incubation values was taken as the pH of the mixture. The finding of maximal activity between pH 7.0 and 8.0 (Figure 3) is in essential agreement with the results of Cohen (9) and others using pig heart muscle as source of transaminase. No change in transaminase activity with time was noted in serum samples stored from ten minutes to 96 hours at room temperature, or for pe-riods of from one hour to two weeks in the re-frigerator (O to 5 C.). The transaminase activity was not changed by freezing or lyophilization of