Preobrazhenskaia M E, Vlasova A L, Ushakova N A
Biull Eksp Biol Med. 1988 Jul;106(7):92-4.
The activity and properties of acid alpha-mannosidase were studied in normal granulocytes and in two types of myeloid cells from patients with chronic myeloid leukemia. The activity of the enzyme in leukemic cells was 2-fold higher than that in normal granulocytes and in morphologically matured myeloid cells. Two latter types of cells did not differ in alpha-mannosidase activity. Kinetic properties, thermo- and pH stability of alpha-mannosidase from normal and leukemic cells were similar. alpha-mannosidase in leukemic and normal cells existed in two forms (A and B), which were easily separated on DEAE-cellulose column. These two forms differed in molecular mass (300 and 290 kD, respectively) and in the degree of sialylation. The quantitative ratios of A and B forms in normal and leukemic cells were different. In normal granulocytes and in mature cells from patients this ratio was 0.60 and 0.67, respectively. In leukemic cells the ratio was found to be 1.31. Thus, in leukemic cells form A of alpha-mannosidase predominanted, whereas in normal cells the predominance of form B was observed. It was suggested therefore that in leukemic cells the enhanced synthesis of alpha-mannosidase occurred in parallel with the accumulation of the B form. This accumulation was assumed as the cause of enhanced activity of the enzyme in immature leukemic cells.
对正常粒细胞以及慢性髓性白血病患者的两种髓系细胞中的酸性α-甘露糖苷酶的活性和特性进行了研究。白血病细胞中该酶的活性比正常粒细胞和形态学成熟的髓系细胞中的活性高2倍。后两种细胞类型的α-甘露糖苷酶活性没有差异。正常细胞和白血病细胞中α-甘露糖苷酶的动力学特性、热稳定性和pH稳定性相似。白血病细胞和正常细胞中的α-甘露糖苷酶以两种形式（A和B）存在，这两种形式在DEAE-纤维素柱上很容易分离。这两种形式的分子量不同（分别为300和290 kD），唾液酸化程度也不同。正常细胞和白血病细胞中A和B形式的定量比例不同。在正常粒细胞和患者的成熟细胞中，该比例分别为0.60和0.67。在白血病细胞中，该比例为1.31。因此，在白血病细胞中α-甘露糖苷酶的A形式占主导，而在正常细胞中观察到B形式占主导。因此有人提出，在白血病细胞中α-甘露糖苷酶合成的增强与B形式的积累同时发生。这种积累被认为是未成熟白血病细胞中该酶活性增强的原因。
