IS THE SUBUNIT THE MINIMAL FUNCTION UNIT OF CREATINE-KINASE

被引:26
作者
WANG, XC
ZHOU, HM
WANG, ZX
TSOU, CL
机构
[1] ACAD SINICA,INST BIOPHYS,NAT LAB BIOMACROMOLEC,BEIJING 100080,PEOPLES R CHINA
[2] TSING HUA UNIV,DEPT BIOL SCI & BIOTECHNOL,TSINGHUA,PEOPLES R CHINA
关键词
(Rabbit brain); (Rabbit muscle); Creatine kinase; Functional unit; Isozyme; Modified subunit;
D O I
10.1016/0167-4838(90)90264-G
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The dimeric rabbit muscle isozyme of creatine kinase (MM) is modified by iodoacetamide to produce the inactive dimer (M′M′) and then hybridized with native dimeric brain isozyme (BB). The hybrid enzyme (M′B),as isolated by PAGE, has the same Km for both ATP and creatine but half the specific activity of the brain isozyme (BB). Likewise, the hybrid of the modified brain with the native muscle isozyme (MB′) has half the activity of the native muscle enzyme. The M′B, MB′ and MB hybrid dimers all have essentially the same electrophoretic properties, and their intrinsic fluorescence and CD spectra in the far-ultraviolet region are very similar to those of the homodimers MM and BB. Similar results were obtained for the hybrid (M″B) containing the muscle enzyme subunit modified at both the thiol group with iodoacetamide and the Trp residue with dimethyl(2-hydroxy-5-nitrobenzyl) sulfonium bromide and the native brain enzyme subunit. The above result suggest strongly the independent catalytic function of the subunit of creatine kinase. © 1990.
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页码:313 / 317
页数:5
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