Human enolase isozymes: electrophoretic and biochemical evidence for three loci
Human enolase isozymes: electrophoretic and biochemical evidence for three loci
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人类烯醇酶同工酶：三个位点的电泳和生化证据
DOI：
10.1111/j.1469-1809.1976.tb00130.x
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发表时间：
1976
影响因子：
1.9
通讯作者：
H. Harris
中科院分区：
文献类型：
--
作者：
JENNIFER M. Pearce;Y. Edwards;H. Harris
1在人体组织中已鉴定出四种主要的烯醇化酶同工酶，分别称为L、M、“中间”和“快速”。M同工酶是骨骼肌和心脏提取物中发现的主要形式，L同工酶是肝脏和大多数其他组织提取物中发现的主要形式。“中间”和“快速”同工酶在脑中最活跃，但在大多数其他组织（包括心脏）中观察到为弱组分，但在骨骼肌中未见。据观察，在胎儿心脏和骨骼肌发育过程中，L型活动下降，而M型活动增加。2比较了主要烯醇化酶同工酶的动力学性质、热稳定性和分子大小。虽然同工酶有许多共同的特征，但“快速”同工酶在热处理时比L或M同工酶更稳定。此外，“快速”同工酶在不存在镁离子的情况下保留其二聚体结构和活性，而L和M同工酶解离并失去活性。"中间“同工酶的性质是中间的L和”快速“同工酶。[3]在室温下储存或在2 m-NaCl存在下冻融，可使“中间”同工酶部分解离为等量的L和“快速”同工酶。相反，L与“快速”和M与“快速”的混合物在冷冻和解冻后产生“中间”同工酶。4从这项研究中得到的证据表明，三个独立的基因位点参与了人类烯醇化酶的决定。其中一个基因座ENO 1决定L同工酶，即同二聚体αα;另一个基因座ENO 2决定“快速”同工酶，即同二聚体ββ;第三个基因座ENO 3决定M同工酶，即同二聚体γγ。“中间”同工酶在脑中被视为强组分，在大多数其他组织中被视为弱组分，被认为是异源二聚体αβ。但在心脏中可能主要是βγ。
1 Four major enolase isozymes have been identified in human tissues and are referred to as L, M, ‘intermediate’ and ‘fast’. The M isozyme is the major form found in skeletal muscle and heart extracts and the L isozyme the major form found in extracts of liver and most other tissues The ‘intermediate’ and ‘ fast’ isozymes are most active in brain but are observed as weak components in most other tissues including heart but are not seen in skeletal muscle. It was observed that during fetal development of heart and skeletal muscle the L form declines in activity while the M form increases in activity. 2 The kinetic properties, heat stabilities and molecular sizes of the main enolase isozymes have been compared. Although the isozymes share many features in common, the ‘fast’ isozyme is more stable when subjected to heat treatment than either the L or M isozymes. Further, the ‘fast’ isozyme retains its dimeric structure and activity in the absence of magnesium ions while the L and M isozymes dissociate and lose activity. The ‘intermediate’ isozyme has properties which are intermediate to those of the L and ‘fast’ isozymes. 3 The ‘intermediate’ isozyme can be partially dissociated to equal quantities of L and ‘fast’ isozymes by storage at room temperature or by freezing and thawing in the presence of 2 m‐NaCl. Conversely, mixtures of L with ‘fast’ and M with ‘fast’ give rise to an ‘intermediate’ isozyme after freezing and thawing. 4 Evidence derived from this study has led to the suggestion that three separate gene loci are involved in the determination of human enolase. It is proposed that one of these, ENO1, determines the L isozyme which is the homodimer αα; another locus, ENO2, determines the ‘fast’ isozyme which is the homodimer ββ; and the third locus, ENO3, determines the M isozyme which is the homodimer γγ. The ‘intermediate’ isozyme seen as a strong component in brain and as a weak component in most other tissues is thought to be the heterodimer αβ. In heart however it is probably mainly βγ.