Complexes Of Liver Alcohol Dehydrogenase Research Articles

Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase.

Chemical model complexes are prepared to represent the active site of an enzyme. In this protocol, a family of tridentate pincer ligand precursors (each possessing two sulfur and one nitrogen donor atom functionalities (SNS) and based on bis-imidazole or bis-triazole compounds) are metallated with CoCl2·6H2O to afford tridentate SNS pincer cobalt(II) complexes. Preparation of the cobalt(II) model complexes for liver alcohol dehydrogenase is facile. Based on a quick color change upon adding the CoCl2·6H2O to acetonitrile solution that contains the ligand precursor, the complex forms rapidly. Formation of the metal complex is complete after allowing the solution to reflux overnight. These cobalt(II) complexes serve as models for the zinc active site in liver alcohol dehydrogenase (LADH). The complexes are characterized using single crystal X-ray diffraction, electrospray mass spectrometry, ultra-violet visible spectroscopy, and elemental analysis. To accurately determine the structure of the complex, its single crystal structure must be determined. Single crystals of the complexes that are suitable for X-ray diffraction are then grown via slow vapor diffusion of diethyl ether into an acetonitrile solution that contains the cobalt(II) complex. For high quality crystals, recrystallization typically takes place over a 1 week period, or longer. The method can be applied to the preparation of other model coordination complexes and can be used in undergraduate teaching laboratories. Finally, it is believed that others may find this recrystallization method to obtain single crystals beneficial to their research.

Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase

Preparation of SNS Cobalt(II) Pincer Model Complexes of Liver Alcohol Dehydrogenase

Structure and dynamics of proteins encapsulated in silica hydrogels by Trp phosphorescence

This report establishes the conditions for monitoring the intrinsic Trp phosphorescence of proteins encapsulated in silica hydrogels and demonstrates the usefulness of the delayed emission for examining potential perturbations of protein structure-dynamics by the silica matrix. Phosphorescence measurements were conducted both in low temperature (140 K) glasses and at ambient temperature on the proteins apo- and Cd-azurin, alkaline phosphatase and liver alcohol dehydrogenase together with the complexes of liver alcohol dehydrogenase with coenzyme analogs ADPR and H 2NADH. While spectral shifts and broadening indicate that alterations of the Trp microenvironment are more marked on superficial regions of the macromolecule the decay kinetics of deeply buried chromophores show that the internal flexibility of the polypeptide in two out of three cases is significantly affected by silica entrapment. Both the intrinsic lifetime and the bimolecular acrylamide quenching constant confirm that, relative to the aqueous solution, in hydrogels the globular fold is more rigid with azurin, looser with alcohol dehydrogenase and substantially unaltered with alkaline phosphatase. It was also noted that large amplitude structural fluctuations, as those involved in coenzyme binding to alcohol dehydrogenase or thermally activated in alkaline phosphatase, were not restricted by gelation. Common features of the three silica entrapped proteins are pronounced conformational heterogeneity and immobilization of rotational motions of the macromolecule in the long time scale of seconds.

Ternary complexes of liver alcohol dehydrogenase

Liver alcohol dehydrogenase (LADH; E.C. 1.1.1.1) provides an excellent system for probing the role of binding interactions with NAD + and alcohols as well as with NADH and the corresponding aldehydes. The enzyme catalyzes the transfer of hydride ion from an alcohol substrate to the NAD + cofactor, yielding the corresponding aldehyde and the reduced cofactor, NADH. The enzyme is also an excellent catalyst for the reverse reaction. X-ray crystallography has shown that the NAD + binds in an extended conformation with a distance of 15 Å between the buried reacting carbon of the nicotinamide ring and the adenine ring near the surface of the horse liver enzyme. A major criticism of X-ray crystallographic studies of enzymes is that they do not provide dynamic information. Such data provide time-averaged and space-averaged models. Significantly, entries in the protein data bank contain both coordinates as well as temperature factors. However, enzyme function involves both dynamics and motion. The motions can be as large as a domain closure such as observed with liver alcohol dehydrogenase or as small as the vibrations of certain atoms in the active site where reactions take place. Ternary complexes produced during the reaction of the enzyme binary entity, E-NAD +, with retinol (vitamin A alcohol) lead to retinal (vitamin A aldehyde) release and the enzyme binary entity E-NADH. Retinal is further metabolized via the E-NAD +-retinal ternary complex to retinoic acid (vitamin A acid). To unravel the mechanistic aspects of these transformations, the kinetics and energetics of interconversion between various ternary complexes are characterized. Proton transfers along hydrogen bond bridges and NADH hydride transfers along hydrophobic entities are considered in some detail. Secondary kinetic isotope effects with retinol are not particularly large with the wild-type form of alcohol dehydrogenase from horse liver. We analyze alcohol dehydrogenase catalysis through a re-examination of the reaction coordinates. The ground states of the binary and ternary complexes are shown to be related to the corresponding transition states through topology and free energy acting along the reaction path.

The protein conformation of Cd-substituted horse liver alcohol dehydrogenase and its metal-site coordination geometry in binary and ternary inhibitor complexes.

The coordination geometry of the metal at the active site in Cd-substituted horse liver alcohol dehydrogenase (LADH) has been investigated for the binary complexes of LADH with imidazole, isobutyramide, decanoic acid and Cl-, and for the ternary complexes of LADH with NADH and imidazole, NADH and isobutyramide, NAD+ and decanoic acid and NAD+ and Cl-, by using the method of perturbed angular correlation of gamma-rays (PAC). The spectral results are consistent with a flexible structure around the metal for the binary complexes with inhibitors. For ternary complexes, however, a rigid structure is observed. An exception is the ternary complex between LADH, NADH and imidazole, in which the metal site is still flexible. Comparing with available structures determined by X-ray crystallography, we found a correlation between open structures and flexible metal sites, and between closed structures and rigid metal sites. This indicates that the PAC technique can be applied to distinguish the two conformations in solution. The spectral parameters, omega(o) and eta, of the experiments, except for the complexes with imidazole, fall into two groups: one with low omega(o) and one with high omega(o) (eta is relatively constant in all experiments). In this work it is clarified that the low omega(o) values are connected with the presence of a negatively charged solvent ligand. Using an angular-overlap approach to interpret the results, the low omega(o) values are found to be compatible with a coordination geometry where the S-Cd-S (Cys174 and Cys46 coordinate to the metal) angle is about 110 degrees as suggested in [Hemmingsen, L., Bauer, R., Danielsen, E., Bjerrum. M. J., Zeppezauer, M., Adolph, H. W., Formicka, G. & Cedergren-Zeppezauer, E. (1995) Biochemistry 34, 7145-7153], whereas high omega(o) values are compatible with an S-Cd-S angle of 130 degrees. The presence of a negatively charged metal ligand, therefore, might trigger the movement of the sulfur of Cys174. As it is believed that alcohols coordinate to the metal as alcoholate ions this could be important for catalysis.

Crystallographic studies of isosteric NAD analogues bound to alcohol dehydrogenase: specificity and substrate binding in two ternary complexes.

CNAD (5-beta-D-ribofuranosylnicotinamide adenine dinucleotide) is an isosteric C-glycosidic analogue of NAD(H) containing a neutral pyridine ring. CPAD (5-beta-D-ribofuranosylpicolinamide adenine dinucleotide) is a closely related pyridine-containing analogue with the pyridine nitrogen on the opposite side of the ring. CNAD is a potent and specific inhibitor of horse liver alcohol dehydrogenase (LADH), binding with a dissociation constant in the nanomolar range. CPAD binds LADH with an affinity comparable to that of NAD. Crystal structures of CNAD and CPAD bound to LADH are presented at 2.4 and 2.7 A, respectively. The two complexes are isomorphous, crystallizing in the triclinic system with cell dimensions different from those seen in previous ternary LADH complexes. Structures were solved using the molecular replacement method and refined to crystallographic R values of 18% (CNAD) and 17% (CPAD). Both inhibitors bind to the "closed" form of LADH in the normal cofactor-binding cleft. The conformation of LADH-bound CPAD closely mimics that of LADH-bound NAD(H). The data suggest that alcohol substrate binds directly to the catalytic zinc atom. In the CNAD complex, the pyridine nitrogen replaces alcohol as the fourth coordination ligand to the active site zinc atom, while all other polar interactions remain the same as those of bound NAD(H). The zinc-nitrogen ligand explains the high affinity of CNAD for LADH.

Molecular orbital studies of enzyme mechanisms. II. Catalytic oxidation of alcohols by liver alcohol dehydrogenase

AbstractSemiempirical (AM1) molecular orbital theory has been used to investigate the oxidation of alcohols at the active site of liver alcohol dehydrogenase (LADH). The model active site consists of a zinc dication coordinated to two methyl‐mercaptans (Cys‐46, Cys‐176), an imidazole (His‐67), and a water. An imidazole (His‐51) hydrogen bonded to a hydroxy‐acetate (Ser‐48) forms the remote base. AM1 calculations that address the two distinct steps in the catalytic mechanism of ethanol oxidation by LADH are reported. These two steps are: (1) the deprotonation of ethanol by imidazole (His‐51) via hydrogen‐bonded hydroxy‐acetate (Ser‐48), creating a proton relay system; and (2) the rate‐limiting hydride transfer step from ethanol C1 to nicotinamide adenine dinucleotide (NAD+), leading to product formation. Detailed calculations have been used to resolve the unsolved problems of mechanisms that have been suggested on the basis of kinetic data and crystal structures of several LADH complexes. We investigated two possible mechanisms for the deprotonation of ethanol, by zinc‐bound OH− and by direct deprotonation of zinc‐bound ethanol by imidazole via hydroxyacetate (Ser‐48). Our calculations show that there is no need for LADH to activate a water molecule at the active site as in many other zinc enzymes. This result agrees with experimental evidence. Our calculations also indicate that substrates are bound in an inner‐sphere‐pentacoordinated complex to the active site zincion. In this case, spectroscopic investigations agree with our results but crystallographic data do not. The highest activation energy is found for the hydride transfer, in agreement with the experiment. Finally, we proposed an alternative mechanism for the mode of action of LADH based upon our results. © 1993 John Wiley & Sons, Inc.

Zinc-activated alcohols in ternary complexes of liver alcohol dehydrogenase.

Activation parameters for each reaction step in the kinetic mechanism of liver alcohol dehydrogenase have been measured for the oxidation of ethanol and the reduction of acetaldehyde. In the oxidation process, the highest enthalpy of activation, 9.7 kcal/mol, occurs for the turnover of the liver alcohol dehydrogenase-NAD(+)-ethanol ternary complex. To investigate if this enthalpy requirement represents a change in the ionization state of ethanol bound in the ternary complex, inhibition of ethanol oxidation was determined using the following series of small, electronegative alcohols with pKa values ranging from 12.37 to 15.5: 2,2,2-trifluoroethanol, 2,2,2-trichloroethanol, 2,2,2-tribromoethanol, 2,2-dichloroethanol, 2,2-difluoroethanol, propargyl alcohol, 3-hydroxypropionitrile, 2-chloroethanol, 2-iodoethanol, 2-methoxyethanol, ethylene glycol, and methanol. The observed inhibition patterns were analyzed according to several kinetic inhibition models; in each case, the best fit model was used to determine the substrate competitive inhibition constant. A plot of the logarithm of these inhibition constants is shown to be dependent on the pKa values of the inhibiting alcohols with a slope approaching -1, indicating that inhibition is controlled by a proton loss from the alcohol. The observed competitive inhibition behavior, coupled with crystallographic studies depicting a direct ligation of an alcohol oxygen to the catalytic zinc ion, indicates that inhibition is controlled by the formation of a zinc-bound alkoxide. Because the inhibiting alcohols are structurally homologous to ethanol, a relationship between the inhibition constant and the inhibiting alcohol's pKa can be derived to show that the pKa of an alcohol bound in a ternary complex is also dependent on its pKa as a free alcohol. Ternary complex pKa values have been determined for ethanol and the inhibiting alcohols.

Fluorescence quenching of Trp-314 of liver alcohol dehydrogenase by oxygen.

The quenching of the fluorescence of liver alcohol dehydrogenase (LADH) by molecular oxygen has been studied by both fluorescence lifetime and intensity measurements. This was done in the presence of 1 M acrylamide which selectively quenches the fluorescence of the surface tryptophan residue, Trp-15, thus allowing us to focus on the quenching of the deeply buried tryptophan, Trp-314, by molecular oxygen. Such studies yielded a Stern-Volmer plot of F0/F with a greater slope than the corresponding tau o/tau plot. This indicates that both dynamic and static quenching of Trp-314 occurs. The temperature dependence of the dynamic quenching of LADH by oxygen was also studied at three temperatures, from which we determined the activation enthalpy for the quenching of Trp-314 to be about 10 kcal/mol. The oxygen quenching of a ternary complex of LADH, NAD+ and trifluoroethanol was also studied. The rate constant for dynamic quenching of Trp-314 by oxygen was found to be approximately the same in the ternary complex as that in the unliganded enzyme.

Crystal-structure determination of reduced nicotinamide adenine dinucleotide complex with horse liver alcohol dehydrogenase maintained in its apo conformation by zinc-bound imidazole.

A crystallographic study to 2.4-A resolution of the ternary complex between horse liver alcohol dehydrogenase (LADH), NADH, and the effector molecule imidazole (Im) (LADH-NADH-Im) is presented. The ligand binding and the changes in the protein structure due to ligand interactions were interpreted from difference electron density maps calculated with phase angles derived from the refined native enzyme model. The complex crystallizes in the orthorhombic space group C2221, and the enzyme structure remains in the apo conformation in which the active-site cleft is not entirely shielded from the solvent. NADH binds in an extended conformation, and the protein-coenzyme interactions are weaker compared to other complexes. The B-stereospecific side of the nicotinamide ring faces the catalytic center (LADH is known to be an A-side-specific enzyme). However, the reactive carbon atom C4 of the ring has a similar position in relation to active-center groups in this structure compared to LADH complexes where the A side of the ring faces the substrate site. The carboxamide group is situated within hydrogen-bonding distance to the sulfur of Cys-46, which is one of the three protein ligands to the active-site zinc atom. The imidazole molecule is directly ligated to the metal ion, which has a roughly tetrahedral geometry in the complex.

Catalysis by Zn 2+-metalloenzymes proceeds via a penta-coordinate metal-OH 2 complex

The active site of a variety of metalloenzymes contains a catalytically essential tetra-coordinate Zn 2+ ion to which a water molecule is a ligand. It is generally assumed that the metal-bound water molecule has no role in catalysis. However, for both the native Zn 2+- and Co 2+-reconstituted forms of carboxypeptidase A (CPA) and liver alcohol dehydrogenase (LADH), we have identified metal ion dependent ionizations that govern steady state kinetic parameters and can be ascribed only to a metal-bond water molecule in catalytically competent reaction intermediates [1, 2]. To assign the coordination environment of the Co 2+ ion in these reaction intermediates, we have identified spectroscopic parameters of the high-spin Co 2+ ion that serve as a direct index of coordination number. Our studies [3] show on the basis of a group theoretical treatment of spin-orbit coupling, together with relationships derived through second-order perturbation theory, that the magnitude of the zero-field splitting (ZFS) of the high-spin Co 2+ ion is a direct monitor of crystal field symmetry and that it follows the order ZFS 4 < ZFS 5 < ZFS 6 where the subscript indicates the coordination number. Measurement of the ZFS in structurally defined coordination complexes confirms this relationship and indicates that the magnitude of 2| D| is 0–13 cm −1 for tetra-coordinate complexes, 20–60 cm 1̄ for penta-coordinate complexes, and 90–130 cm −1 for hexa-coordinate complexes. Application of this theory to measurements of the ZFS of CoCPA and CoLADH shows that the active site metal ion is tetra-coordinate in the free enzyme and is altered to a penta-coordinate complex in true reaction intermediates. In these intermediates the metal ion coordinates both the substrate and a water molecule simultaneously. Together with kinetic studies identifying ionizations of a metal-bound water molecule and showing that the reaction pathway is identical for Zn 2+- and Co 2+-enzymes, the results require that, upon formation of a penta-coordinate Zn 2+OH 2 complex, breakdown of the acyl-enzyme (mixed anhydride) reaction intermediate of CPA occurs via metal-hydroxide nucleophilic attack on the carbonyl carbon of the scissile bond while in the physiologically active, ternary enzyme-NAD +- alcohol complex of LADH a neutral metal-bound water molecule serves as the base catalyst for proton abstraction. The results of these studies show that the metal-bound water has an integral catalytic role in CPA and LADH. It is probable that the metal-OH 2 complex has similarly a functional role in other Zn 2+- metalloenzymes. (Supported by NIH grant GM 21900).

Crystal structure determinations of coenzyme analogue and substrate complexes of liver alcohol dehydrogenase: binding of 1,4,5,6-tetrahydronicotinamide adenine dinucleotide and trans-4-(N,N-dimethylamino)cinnamaldehyde to the enzyme.

Crystal structure determinations of coenzyme analogue and substrate complexes of liver alcohol dehydrogenase: binding of 1,4,5,6-tetrahydronicotinamide adenine dinucleotide and trans-4-(N,N-dimethylamino)cinnamaldehyde to the enzyme.

77] Covalent enzyme—coenzyme complexes of liver alcohol dehydrogenase and NAD

This chapter focuses on the synthesis of covalent enzyme-coenzyme complexes of liver alcohol dehydrogenase and nicotinamide adenine dinucleotide (NAD). The problems of retention and regeneration are solved by two methods used for the preparation of complexes between alcohol dehydrogenase and NAD. The first method consists of the immobilization of the reduced NAD analog, N 6 -[ N -(6-aminohexyl)carbamoylmethyl]NADH, and the enzyme, liver alcohol dehydrogenase, to a support such activated agarose. The second method provides more alternatives for regeneration. The broad substrate specificity of liver alcohol dehydrogenase for redox reactions makes it a versatile enzyme for use in organic reactions. The complex of liver alcohol dehydrogenase-NADH and agarose is stable and easy to prepare and might be useful in the production of various ketones, aldehydes, and alcohols. The soluble complex of liver alcohol dehydrogenase and NAD also function in enzyme reactions with other NAD-dependent dehydrogenases where both enzymes share a common coenzyme, though it is covalently bound to liver alcohol dehydrogenase.

Investigation of the nature of enzyme--coenzyme interactions in binary and ternary complexes of liver alcohol dehydrogenase with coenzymes, coenzyme analogues, and substrate analogues by ultraviolet absorption and phosphorescence spectroscopy.

The difference spectra of binary and ternary complexes of horse liver alcohol dehydrogenase with oxidized and reduced nicotinamide adenine dinucleotides, nicotinamide 1,N6-ethenoadenine dinucleotide, and adenosine diphosphate ribose along with a number of substrate analogues have been measured. These spectra bear a very close resemblance to those obtained by perturbation of the coenzyme(s) and their analogues by acid, NaCl, dioxane, or tert-butyl alcohol. It is inferred that the coenzymes experience a combination of ionic and nonpolar environments at the adenine binding site of the enzyme. This is borne out by published X-ray crystallographic results. The phosphorescence spectra do not indicate the presence of ionized tyrosine in ternary complexes invovling enzyme, coenzyme, and substrate analogues. The ultraviolet spectra can be explained as arising from the perturbation of the coenzyme chromophores upon binding to the enzyme without having to invoke tyrosine ionization.

Determination of the equilibrium distibution between alcohol and aldehyde substrates when bound to horse liver alcohol dehydrogenase using magnetic resonance.

The interactions of horse liver alcohol dehydrogenase (LADH) with the rho-trifluoromethyl derivatives of benzyl alcohol, benzaldehyde, and benzoic acid have been investigated by use of 19F nuclear magnetic resonance. The aldehyde and alcohol are good substrates for the enzyme and display kinetic characteristics similar to other alcohol/aldehyde pairs. In single-turnover experiments with NADH, rho-(trifluoromethyl)benzaldehyde shows biphasic kinetics similar to those shown by other aromatic aldehydes, which led Bernhard and co-workers [Bernard, S. A., Dunn, M. F., Luisi, P. L., & Shack, P. (1970) Biochemistry 9, 185] to propose half-of-the-sites reactivity for this enzyme. Fluorine magnetic resonance demonstrates that under equilibrium conditions at 4 degrees C and pH 8.75 rho-(trifluoromethyl)benzyl alcohol binds to LADH with a dissociation constant of 1 x 10(-3) M. Addition of 1 equiv of NAD to a stoichiometric complex of LADH and the alcohol generates a discrete resonance. This resonance corresponds to the ternary complex of LADH, NAD, and alcohol with little contribution from the NADH and aldehyde ternary complex. Quantitation shows that the bound NAD-alcohol pair is favored by at least a factor of 20 over the bound NADH-aldehyde pair at equililbrium. These results are consistent with explanations for the biphasic kinetics which involve half-of-the-sites reactivity of multiple steps in the reaction of each catalytic site. These results eliminate explanations for the biphasic kinetics of this system which require this equilibrium constant to have a value near unity or those which give greatest thermodynamic stability to the heterodimer LADH [(NAD-alcohol)(NADH-aldehyde)].

Studies of enzyme-mediated reactions. Part 11. Experiments on the dismutation of aldehyde to alcohol and carboxylic acid by the complex of liver alcohol dehydrogenase and NAD+

[1-3H1] Heptanal undergoes dismutation in the presence of the complex of liver alcohol dehydrogenase and NAD+ to yield unlabelled heptanoic acid and (1RS)-[1-3H1]heptanol with double the specific radioactivity, thus demonstrating transfer of the formyl hydrogen from one half of the sample to the other. Conditions are found for reducing the incidence of this dismutation process.

The Conformation of Adenosine Diphosphoribose and 8-Bromoadenosine Diphosphoribose when Bound to Liver Alcohol Dehydrogenase

8-Bromo-adenosine diphosphoribose (br8 ADP-Rib) and nicotinamide 8-bromoadenine dinucleotide (Nbr8AD+) which are analogues of the coenzyme NAD+, were prepared and their liver alcohol dehydrogenase complexes studied by crystallographic methods. Nbr8AD+ is active in alcohol dehydrogenase complexes studied by crystallographic methods. Nbr8AD+ is active in hydrogen transport and br8ADP-Rib is a coenzyme competitive inhibitor for the enzymes liver alcohol dehydrogenase and yeast alcohol dehydrogenase. X-ray data were obtained for the complex between liver alcohol dehydrogenase and br8ADP-Rib to 0.45 nm resolution and for the liver alcohol dehydrogenase-adenosine diphosphoribose complex to 0.29-nm resolution. The conformations of these analogues were determined from the X-ray data. It was found that ADP-Rib had a conformation very similar to the corresponding part of NAD+, when NAD+ is bound to lactate and malate dehydrogenase. br8ADP-Rib had the same anti conformation of the adenine ring with respect to the ribose as ADP-Rib and NAD+, in contrast to the syn conformation found in 8-bromo-adenosine. The overcrowding at the 8-position is relieved in br8ADP-Rib by having the ribose in the 2' endo condormation instead of the usual 3' endo as in ADP-Rib and NAD+.

Conformational changes in liver alcohol dehydrogenase upon nucleotide binding: Detection by circular dichroism of dye complexes

Michler's ketone, the ketone analog of auramine O, binds to liver alcohol dehydrogenase with an affinity comparable to that of auramine O, yields similar induced circular dichroism bands, and its binding is enhanced in the same way by binding of coenzyme fragments. These observations suggest that (a) Michler's ketone binds to liver alcohol dehydrogenase in a similar manner and at the same site as does auramine O and (b) the enhancement of auramine O and Michler's ketone binding by coenzyme fragments is not due to electrostatic interactions since both the positively charged auramine O and the neutral Michler's ketone show similar effects. Observation of similar enhancement of auramine O binding by GMP and ϵ-AMP as well as the activesite topology suggested by fluorescence and X-ray studies argue against any direct interaction of the dye with the purine ring. We, therefore, ascribe the enhanced binding of dye in ternary complexes to a conformational change in liver alcohol dehydogenase induced by the binding of coenzyme fragments. Studies of the circular dichroism of liver alcohol dehydrogenase complexes with 2,2′-bipyridyl are also reported.

An unproductive binary complex of liver alcohol dehydrogenase and a chromophoric aldehyde.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUnproductive binary complex of liver alcohol dehydrogenase and a chromophoric aldehydeJames T. McFarland, Yu Heng Chu, and Jeffrey W. JacobsCite this: Biochemistry 1974, 13, 1, 65–69Publication Date (Print):January 1, 1974Publication History Published online1 May 2002Published inissue 1 January 1974https://doi.org/10.1021/bi00698a011RIGHTS & PERMISSIONSArticle Views20Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Circular dichroism of liver alcohol dehydrogenase complexes with auramine O.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCircular dichroism of liver alcohol dehydrogenase complexes with auramine OJeffrey S. Wicken and Robert W. WoodyCite this: Biochemistry 1973, 12, 18, 3459–3466Publication Date (Print):August 1, 1973Publication History Published online1 May 2002Published inissue 1 August 1973https://doi.org/10.1021/bi00742a016RIGHTS & PERMISSIONSArticle Views73Altmetric-Citations14LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts