乙酰唑胺和4-硝基苯硫酚离子与牛碳酸酐酶二价金属离子衍生物的相互作用。
Interaction of acetazolamide and 4-nitrothiophenolate ion with bivalent metal ion derivatives of bovine carbonic anhydrase.
作者信息
Harrington P C, Wilkins R G
出版信息
Biochemistry. 1977 Feb 8;16(3):448-54. doi: 10.1021/bi00622a017.
The stability and rate constants for the interaction of acetazolamide (diamox) and 4-nitrothiophenolate ion (NTP) with the bivalent Mn, Co, Ni, Cu and Cd forms of bovine carbonic anhydrase have been measured by utilizing the distinct visible spectra of each metalloenzyme-NTP adduct. Differing stabilities of the various NTP and (particularly) diamox complexes reside mainly in varying values for the dissociation rate constants (kd). Intrinsic formation rate constants (for the acid form of the enzyme reacting with the basic form of the ligand) are uniformly high (greater than or equal 2 X 10(7) M-1 s-1 at 25 degrees C). Invariance of kd with pH and a bell-shaped log K-pH profile with the Cu-enzyme adducts are features observed previously with the native enzyme. Binding of NTP with the Cu and Cd metalloenzymes is stronger than to the native form.
利用每种金属酶 - NTP加合物独特的可见光谱，已测定了乙酰唑胺（醋氮酰胺）和4 - 硝基硫酚离子（NTP）与二价锰、钴、镍、铜和镉形式的牛碳酸酐酶相互作用的稳定性和速率常数。各种NTP和（特别是）醋氮酰胺配合物不同的稳定性主要在于解离速率常数（kd）的不同值。内在形成速率常数（对于酶的酸性形式与配体的碱性形式反应）在25℃时均较高（大于或等于2×10⁷ M⁻¹ s⁻¹）。kd随pH不变以及铜酶加合物的log K - pH呈钟形曲线是先前在天然酶中观察到的特征。NTP与铜和镉金属酶的结合比与天然形式的结合更强。
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