The Value of Galactose Phosphate Determinations in the treatment of Galactosaemia
The Value of Galactose Phosphate Determinations in the treatment of Galactosaemia
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磷酸半乳糖测定在半乳糖血症治疗中的价值
DOI：
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发表时间：
1960
影响因子：
5.2
通讯作者：
V. Schwarz
中科院分区：
文献类型：
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作者：
V. Schwarz
遗传性半乳糖血症现在被认为是由于缺乏一种单一的酶，即半乳糖-1磷酸尿苷转移酶*(Kalkar，Anderson和Isselbacher，1956)。该酶是与半乳糖代谢有关的三种酶中的第二种，催化Gal-I-P转化为G-1-P，如公式(2)所示：Gal+ATPGal-I-P+ADP(1)Gal-I-P+UDPG=G-1-P+UDPga(2)UDPga=UDPG(3)当半乳糖血症患者摄入半乳糖时，步骤(2)的半乳糖代谢受阻可能导致Gal-L-P的积聚。在患有半乳糖血症的未经治疗的婴儿的红细胞中，或在与半乳糖体外孵育的治疗病例的红细胞中，已经证明了这种磷酸盐的积累(Schwarz，Golberg，Komrower和Holzel，1956；Kalck等，1956)。基于这一观察结果，先前已经报道过半乳糖血症的诊断试验(Schwarz，Holzel和Komrower，1958)。Gal-L-P在细胞内的积累似乎导致了严重的红细胞代谢紊乱，表现为呼吸频率的下降和磷酸盐代谢的普遍紊乱(Schwarz等人，1956年；Komrower，Schwarz，Holzel和Golberg，1956；Penington和Prankerd，1958)。在缺乏尿苷转移酶的大肠杆菌突变体中也显示了类似的干扰：当培养物与半乳糖孵育时，它表现出在开始生长之前有一个较长的滞后期，在此之前是细胞内Gal-I-P的积累(Kurahashi和Wahba，1958)。最近的证据表明，Gal-I-P可能对一些酶--磷酸葡萄糖变位酶、G-6-P磷酸酶和脱氢酶产生抑制作用(Sidbury，1957；Ginsburg和Neufeld，1957；Lerman，1960)。到目前为止，Gal-L-P仅在半乳糖血症婴儿的红细胞中被证实。肝脏是半乳糖正常代谢的主要部位，预计会表现出类似的、甚至更大的这种磷酸盐的积累。从理论上讲，人体的所有细胞或多或少都被赋予了所有的酶，因此，一种酶的遗传缺陷可能会在所有组织中都能感受到。这种沟通的目的有三个：证明GAL-I-P实际上确实在几个(如果不是全部)组织中蓄积；提请注意定期评估红细胞GAL-L-P作为治疗充分性指导的价值；提出一种改进的GAL-I-P测定方法。下面报告的Gal-I-P值是通过先前发表的方法(Schwarz等人，1958)获得的。由于这种方法的发展和大多数测定，已经有了纯Gal-I-P，因此可以对其测定的效率进行评估。最近的实验表明，最初的方法可能涉及半乳糖的损失，这是由于蒸发干燥后留下的盐不可逆转地吸附或夹带在其中。为了尽可能克服这一缺陷，并保持半乳糖与其他碳水化合物或还原物质层析分离所产生的方法的特异性，设计了以下方法。半乳糖-L-P肝素化静脉血的测定(约2毫升)可以在冰中(不冷冻)保存几个小时，然后进行离心机
Hereditary galactosaemia is now known to be due to the deficiency of a single enzyme, galactose-lphosphate uridyl transferase* (Kalckar, Anderson and Isselbacher, 1956). This enzyme, the second in the chain of three enzymes concerned with the metabolism of galactose, catalyses the conversion of gal-I-P to G-1-P, as shown in equation (2): gal + ATP gal-I-P + ADP (1) gal-i-P + UDPG = G-1-P + UDPgal (2) UDPgal = UDPG (3) The block in galactose metabolism at step (2) would be expected to lead to an accumulation of gal-l-P when galactosaemic individuals ingest galactose. An accumulation of this phosphate has been demonstrated in the erythrocytes of untreated infants suffering from galactosaemia, or in the erythrocytes of treated cases after incubation with galactose in vitro (Schwarz, Golberg, Komrower and Holzel, 1956; Kalckar et al., 1956). A diagnostic test for galactosaemia, based on this observation, has been reported previously (Schwarz, Holzel and Komrower, 1958). The intracellular accumulation of gal-l-P appears to lead to a serious disturbance of erythrocyte metabolism, as indicated by a fall in the respiratory rate and by a general derangement of phosphate metabolism (Schwarz et al., 1956; Komrower, Schwarz, Holzel and Golberg, 1956; Penington and Prankerd, 1958). An analogous disturbance has been demonstrated in a mutant of E. coli deficient in uridyltransferase: on incubation of the culture with galactose, it evinces a prolonged lag phase before the onset of growth, which is preceded by intracellular accumulation of gal-i-P (Kurahashi and Wahba, 1958). Recently evidence has been presented which indicates that gal-i-P may exert an inhibitory effect on a number of enzymes-phosphoglucomutase, G-6-P phosphatase and dehydrogenase (Sidbury, 1957; Ginsburg and Neufeld, 1957; Lerman, 1960). So far gal-l-P has been demonstrated only in the erythrocytes of galactosaemic infants. The liver, being the main site at which galactose is normally metabolized, would be expected to show a similar, or even greater, accumulation of this phosphate. Theoretically, all cells of the body are endowed, to a greater or lesser extent, with all enzymes and a hereditary deficiency in one enzyme might therefore make itself felt in all tissues. The purpose of this communication is threefold: to demonstrate that gal-I-P does, in fact, accumulate in several, if not all, tissues; to draw attention to the value of assessing erythrocyte gal-l-P at regular intervals as a guide to the adequacy of treatment; to present an improved method for the determination of gal-i-P. The gal-I-P values reported below were obtained by the method published previously (Schwarz et al., 1958). Since this method was evolved and most of the determinations made, pure gal-i-P has become available, thus permitting an assessment of the efficiency of its determination. Recent experiments have shown that the original method may involve losses of galactose resulting from irreversible adsorption on, or entrainment in, the salts left after evaporation to dryness. To overcome this defect as far as possible, and still retain the specificity of the method accruing from chromatographic separation of galactose from other carbohydrate or reducing substances, the following method has been devised. Determination of Gal-l-P Heparinized venous blood (about 2 ml.) which may be kept in ice (not frozen) for a few hours, is centrifuged