scholarly journals Engineering enzyme catalysis: an inverse approach

2019 ◽  
Vol 39 (2) ◽  
Author(s):  
Clare F. Megarity

Abstract Enzymes’ inherent chirality confers their exquisite enantiomeric specificity and makes their use as green alternatives to chiral metal complexes or chiral organocatalysts invaluable to the fine chemical industry. The most prevalent way to alter enzyme activity in terms of regioselectivity and stereoselectivity for both industry and fundamental research is to engineer the enzyme. In a recent article by Keinänen et al., published in Bioscience Reports 2018, ‘Controlling the regioselectivity and stereoselectivity of FAD-dependent polyamine oxidases with the use of amine-attached guide molecules as conformational modulators’, an inverse approach was presented that focuses on the manipulation of the enzyme substrate rather than the enzyme. This approach not only uncovered dormant enantioselectivity in related enzymes but allowed for its control by the use of guide molecules simply added to the reaction solution or covalently linked to an achiral scaffold molecule.

2020 ◽  
Vol 21 (20) ◽  
pp. 7465 ◽  
Author(s):  
Vasilisa V. Krasitskaya ◽  
Eugenia E. Bashmakova ◽  
Ludmila A. Frank

The functioning of bioluminescent systems in most of the known marine organisms is based on the oxidation reaction of the same substrate—coelenterazine (CTZ), catalyzed by luciferase. Despite the diversity in structures and the functioning mechanisms, these enzymes can be united into a common group called CTZ-dependent luciferases. Among these, there are two sharply different types of the system organization—Ca2+-regulated photoproteins and luciferases themselves that function in accordance with the classical enzyme–substrate kinetics. Along with deep and comprehensive fundamental research on these systems, approaches and methods of their practical use as highly sensitive reporters in analytics have been developed. The research aiming at the creation of artificial luciferases and synthetic CTZ analogues with new unique properties has led to the development of new experimental analytical methods based on them. The commercial availability of many ready-to-use assay systems based on CTZ-dependent luciferases is also important when choosing them by first-time-users. The development of analytical methods based on these bioluminescent systems is currently booming. The bioluminescent systems under consideration were successfully applied in various biological research areas, which confirms them to be a powerful analytical tool. In this review, we consider the main directions, results, and achievements in research involving these luciferases.


1993 ◽  
Vol 39 (5) ◽  
pp. 543-547 ◽  
Author(s):  
Elsayed E. Wagih ◽  
Jacqueline Fletcher

A new microtechnique that detects enzyme activity in prokaryotes is described. The technique, designated zymoblot, is based on the immobilization of negatively charged enzymes from an alkaline extract spotted onto a nitrocellulose membrane. The presence of specific enzyme activity in the extract is selectively assayed with a reaction mixture containing the corresponding substrate. The enzyme–substrate reaction produces an insoluble colored product that accumulates at the site. The zymoblot technique offers the advantages of simplicity, sensitivity, reproducibility, speed, and the use of microquantities of reactants. The protein in the spot can be visualized by a technique termed "proteinblot," in which the protein is stained with Coomassie blue. Esterase and tyrosinase were detected by the zymoblot method in six spiroplasmas including four strains of Spiroplasma citri, one of Spiroplasma kunkelii, and one of Spiroplasma melliferum, and two bacteria, Pseudomonas syringae pv. syringae B301D and Escherichia coli K-12. Acid phosphatase, alkaline phosphatase, alanine dehydrogenase, peroxidase, and 6-phosphogluconate dehydrogenase were not detected in any of the spiroplasmas, but were each detected in one or both of the walled bacteria.Key words: spiroplasma, enzyme, protein, zymoblot.


1973 ◽  
Vol 133 (3) ◽  
pp. 521-527 ◽  
Author(s):  
David L. Wright ◽  
David T. Plummer

1. Acetylcholinesterase from human erythrocytes was solubilized with Triton X-100 in strong salt solution and partially purified by (NH4)2SO4 fractionation. This preparation showed three main bands of enzyme activity after electrophoresis on polyacrylamide gel and incubation with either α-naphthyl acetate or acetylthiocholine as enzyme substrate. Two of the multiple forms were completely inhibited by 10μm-eserine and one only partially. Treatment with neuraminidase had no effect on the electrophoretic pattern; therefore sialic acid does not appear to determine or affect the ratios of the acetylcholinesterase multiple forms, unlike those of the serum cholinesterase. 2. Chromatography of the preparation on Sephadex G-200 revealed one major peak of enzyme activity and a suggestion of two minor zones of mol.wt. 546000, 184000 and 93000 (i.e. in the proportion 6:2:1). The main peak was almost completely separated from the Triton X-100 and the overall purification was about 600-fold. Further attempts to purify the enzyme by absorption on calcium phosphate gels were unsuccessful. 3. Electrophoresis of the enzyme preparation on a polyacrylamide gradient for 24h revealed three main bands that corresponded to the three values for molecular weights obtained by column chromatography. After 70h of electrophoresis a further three zones of activity developed making six molecular entities, the molecular weights of which were simple multiples of a monomer, thus resembling the cholinesterase found in serum.


2004 ◽  
Vol 359 (1448) ◽  
pp. 1309-1320 ◽  
Author(s):  
Rachel V. Dunn ◽  
Roy M. Daniel

Although there are varying estimates as to the degree of enzyme hydration required for activity, a threshold value of ca . 0.2 g of water per gram of protein has been widely accepted. The evidence upon which this is based is reviewed here. In particular, results from the use of gas–phase substrates are discussed. Results using solid–phase enzyme–substrate mixtures are not altogether in accord with those obtained using gas–phase substrates. The use of gaseous substrates and products provides an experimental system in which the hydration of the enzyme can be easily controlled, but which is not limited by diffusion. All the results show that increasing hydration enhances activity. The results using gas–phase substrates do not support the existence of a critical hydration value below which enzymatic activity is absent, and suggest that enzyme activity is possible at much lower hydrations than previously thought; they do not support the notion that significant hydration of the surface polar groups is required for activity. However, the marked improvement of activity as hydration is increased suggests that water does play a role, perhaps in optimizing the structure or facilitating the flexibility required for maximal activity.


2012 ◽  
Vol 554-556 ◽  
pp. 1237-1242
Author(s):  
Xu Cong Yu ◽  
Lin Li ◽  
Quan Yi Fu ◽  
Bing Li

In this article, investigation on the effect of microwave treatment on the catalysis of papain had been carried out. According to the results, the thermal effect was found to be the main factor to cause inactivation of enzyme. The kinetic parameters and the fluorescence spectroscopy implied that the microwave processing had changed the conformation of the enzyme molecules and thus affected its activity. The results also showed that the microwave treatment had not changed the optimum pH value of the enzyme catalysis, and the inactivation rate of the enzyme was inversely proportional to the concentration of the enzyme. In addition, a certain concentration of the disodium EDTA media had been found to effectively protect the enzyme activity in microwave processing.


2016 ◽  
Vol 88 (9) ◽  
pp. 4714-4723 ◽  
Author(s):  
Margarida C. Altas ◽  
Evgeny Kudryashov ◽  
Vitaly Buckin

1983 ◽  
Vol 213 (3) ◽  
pp. 603-607 ◽  
Author(s):  
C O'Fagain ◽  
B M Butler ◽  
T J Mantle

The effect of pH on the kinetics of rat liver arylsulphatases A and B is very similar and shows that two groups with pK values of 4.4-4.5 and 5.7-5.8 are important for enzyme activity. Substrate binding has no effect on the group with a pK of 4.4-4.5; however, the pK of the second group is shifted to 7.1-7.5 in the enzyme-substrate complex. An analysis of the effect of pH on the Ki for sulphate inhibition suggests that HSO4-is the true product. A model is proposed that involves the two ionizing groups identified in the present study in a concerted general acid-base-catalysed mechanism.


2021 ◽  
Author(s):  
Rana El Masri ◽  
Amal Seffouh ◽  
Caroline Roelants ◽  
Ilham Seffouh ◽  
Evelyne Gout ◽  
...  

AbstractSulfs represent a class of unconventional sulfatases, which differ from all other members of the sulfatase family by their structures, catalytic features and biological functions. Through their specific endosulfatase activity in extracellular milieu, Sulfs provide an original post-synthetic regulatory mechanism for heparan sulfate complex polysaccharides and have been involved in multiple physiopathological processes, including cancer. However, Sulfs remain poorly characterized enzymes, with major discrepancies regarding their in vivo functions. Here we show that human Sulf-2 (HSulf-2) features a unique polysaccharide post-translational modification. We identified a chondroitin/dermatan sulfate glycosaminoglycan (GAG) chain, attached to the enzyme substrate binding domain. We found that this GAG chain affects enzyme/substrate recognition and tunes HSulf-2 activity in vitro and in vivo using a mouse model of tumorigenesis and metastasis. In addition, we showed that mammalian hyaluronidase acted as a promoter of HSulf-2 activity by digesting its GAG chain. In conclusion, our results highlight HSulf-2 as a unique proteoglycan enzyme and its newly-identified GAG chain as a critical non-catalytic modulator of the enzyme activity. These findings contribute in clarifying the conflicting data on the activities of the Sulfs and introduce a new paradigm into the study of these enzymes.


1994 ◽  
Vol 59 (2) ◽  
pp. 467-472 ◽  
Author(s):  
Jana Barthová ◽  
Irena Hulová ◽  
Miroslava Birčáková

The lactate dehydrogenase was isolated from soybean (Glycine max. L.) by a procedure that employed biospecific chromatography on a column of Blue-Sepharose CL-6B. The participation of the guanidine group of arginine residues in the mechanism of enzyme action was determined through kinetic and chemical modification studies. The dependence of enzyme activity on pH was followed in the alkaline region (pH 8.6 - 12.8). The pK values found were 12.4 for the enzyme substrate complex and 11.1 for the free enzyme. The enzyme was inactivated by phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione and p-hydroxyphenylglyoxal reagents used in modification experiments. Kinetic analysis of the modification indicated that one arginine residue is modified when inactivation occurs. No effect was observed on the rate of inactivation upon addition of coenzyme. The extent of enzyme modification by p-hydroxyphenylglyoxal was determined. It appears there are at least two arginine residues in the active site of the enzyme.


1997 ◽  
Vol 62 (8) ◽  
pp. 1150-1158 ◽  
Author(s):  
Milan Šolc

The free intramolecular energy flow can be restricted by the presence of a heavy atom in the molecule. As a result of this restriction, adsorbed molecules bonded on the metal surface and/or substrate molecules in the enzyme-substrate complex with a metal atom near the binding site can have a higher vibrational energy than the surroundings. The reaction rate is then enhanced by this energy localization.


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