scholarly journals The molecular basis of the effect of temperature on enzyme activity

2009 ◽  
Vol 425 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Roy M. Daniel ◽  
Michelle E. Peterson ◽  
Michael J. Danson ◽  
Nicholas C. Price ◽  
Sharon M. Kelly ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Active Site ◽  
Classical Model ◽  
Active Form ◽  
Enzyme Reaction ◽  
Effect Of Temperature ◽  
Enzyme Active Site ◽  
Temperature Ranges ◽  
The Difference ◽  
Two State Model

Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the two-state (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme's catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

A counterintuitive approach to treat enzyme deficiencies: use of enzyme inhibitors for restoring mutant enzyme activity

2008 ◽  
Vol 389 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Jian-Qiang Fan
Keyword(s):  
Enzyme Activity ◽  
Active Site ◽  
Protein Misfolding ◽  
Enzyme Inhibitors ◽  
Lysosomal Storage ◽  
New Paradigm ◽  
Inherited Disorders ◽  
Pharmacological Chaperone ◽  
Mutant Proteins ◽  
Enzyme Active Site

Abstract Pharmacological chaperone therapy is an emerging counterintuitive approach to treat protein deficiencies resulting from mutations causing misfolded protein conformations. Active-site-specific chaperones (ASSCs) are enzyme active-site directed small molecule pharmacological chaperones that act as a folding template to assist protein folding of mutant proteins in the endoplasmic reticulum (ER). As a result, excessive degradation of mutant proteins in the ER-associated degradation (ERAD) machinery can be prevented, thus restoring enzyme activity. Lysosomal storage disorders (LSDs) are suitable candidates for ASSC treatment, as the levels of enzyme activity needed to prevent substrate storage are relatively low. In addition, ASSCs are orally active small molecules and have potential to gain access to most cell types to treat neuronopathic LSDs. Competitive enzyme inhibitors are effective ASSCs when they are used at sub-inhibitory concentrations. This whole new paradigm provides excellent opportunity for identifying specific drugs to treat a broad range of inherited disorders. This review describes protein misfolding as a pathophysiological cause in LSDs and provides an overview of recent advances in the development of pharmacological chaperone therapy for the diseases. In addition, a generalized guidance for the design and screening of ASSCs is also presented.

scholarly journals Kinetics of protein modification reactions. Plot of fractional enzyme activity versus extent of protein modification in cases where all modifiable groups are essential for enzyme activity

1984 ◽  
Vol 223 (1) ◽  
pp. 259-262 ◽  
Author(s):  
E T Rakitzis
Keyword(s):  
Enzyme Activity ◽  
Active Site ◽  
Protein Modification ◽  
Enzyme Molecule ◽  
Single Group ◽  
Initial Portion ◽  
Enzyme Active Site ◽  
Kinetics Of

The plot of fractional enzyme activity versus extent of protein modification, for cases where all enzyme modifiable groups of a certain kind are essential for activity, is found to be nearly independent of the number, per enzyme active site, of modifiable groups involved. Such plots usually, by a fallacious extension of the initial portion of the plot on the extent-of-modification axis, are interpreted to mean the modification of one single group per enzyme active site (or per enzyme molecule). The possible relevance of these findings to cases in the literature is discussed.

scholarly journals α-Bromo-4-amino-3-nitroacetophenone, a new reagent for protein modification. Modification of the methionine-290 residue of porcine pepsin

1980 ◽  
Vol 187 (2) ◽  
pp. 345-352 ◽  
Author(s):  
N I Tarasova ◽  
G I Lavrenova ◽  
V M Stepanov
Keyword(s):  
Enzyme Activity ◽  
Carboxy Group ◽  
Active Site ◽  
Protein Modification ◽  
Phenacyl Bromide ◽  
Enzyme Molecule ◽  
Noticeable Effect ◽  
Porcine Pepsin ◽  
Enzyme Active Site ◽  
Phenacyl Bromides

A new coloured reagent for protein modification, alpha-bromo-4-amino-3-nitroacetophenone (NH2BrNphAc), was synthesized. The reagent was found to alkylate specifically the methionine-290 residue of porcine pepsin below pH 3 at 37 degrees C, which lead to a 45% decrease of enzyme's activity towards haemoglobin. The effect of this reagent as well as that of other phenacyl bromides on the activity of pepsin appeared to be a result of steric hindrance caused by the attachment of bulky reagent residue to the edge of the cleft harbouring the enzyme active site. Only marginal reaction with the co-carboxy group of aspartic acid-315 was found under the above conditions. More pronounced esterification of carboxy groups (up to one residue per enzyme molecule) occurred when the pH was shifted to 5.2. The latter modification had no noticeable effect on enzyme activity, thus disproving a previously held assumption that pepsin inactivation by phenacyl bromide is due to the carboxy-group esterification. alpha-Bromo-4-amino-3-nitroacetophenone forms derivatives with characteristic u.v. spectra when it reacts with methionine, histidine, aspartic and glutamic acid residues, and may be recommended as a reagent for protein modification.

scholarly journals The Organ Distribution, Characterization and Modification of Acetylcholinesterase Activity in Adult African Grasshopper: Zonocerus sp Linn.

2019 ◽  
pp. 1-9
Author(s):  
E. A. Fajemisin ◽  
O. S. Bamidele ◽  
S. O. Ogunsola ◽  
E. A. Aiyenuro
Keyword(s):  
Enzyme Activity ◽  
Protein Content ◽  
Active Site ◽  
Ache Activity ◽  
Specific Activity ◽  
Acetylcholinesterase Activity ◽  
Organ Distribution ◽  
Enzyme Active Site ◽  
University Of Technology ◽  
Tryptophan Residues

Aim: To determine the organ distribution and characterization of acetylcholinesterase in the adult African variegated grasshoppers – Zonocerus variegatus and Zonocerus elegans. (Zonocerus Sp. Linn) Place and Duration of the Study: The insect model: African variegated grasshoppers are gotten from the Open green fields at the Federal University of Technology, Akure, Nigeria, and research was carried out between March and June, 2016 in the Enzymology laboratory, Biochemistry department, Federal University of Technology, Akure, Nigeria. Methodology: Twenty (20) adults variegated grasshoppers were taken from the Open field in the University community, and taken to the Biology department for Identification. After identification, the specimen was weighed, freeze, dissected into fractions (Head, Thorax and Abdomen) and then homogenized to get the crude protein extract. The crude enzyme extract is further purified using the Ion-exchange chromatography with column bed packed with DEAE – Sephadex A50. The protein content of the purified AChE was determined using the Lowry method while the Acetylcholinesterase activity was determined by the Ellman’s assay procedures. The characterization of AChE was tested by modifying agent such as N-Bromo Succinamide (NBS) which confirms the presence of key aromatic proteins involve in catalysis at the active site of the enzyme. Results: The protein concentration according to their fractions: Head (35.7%), Thorax (29.2%), and Abdomen (35.1%). The AChE activity according to their fractions: Head (38.6%), Thorax (23.7%), and Abdomen (37.7%). The specific activity which relates the AChE activity to protein content is given: Head (28.8%), Thorax (40.4%), and Abdomen (30.8%). From the Organ distribution and AChE activity, it was observed that the Head Fractions has the Highest protein content, and Enzyme activity. Comparatively, there are slight differences in the Enzyme activity of the Head and Abdominal fractions which represents the two peaks in the AChE chart. As well, the thorax has the highest specific activity. The modification by the chemical agent NBS shows a drastic decrease (about 50%) in Enzyme activity and characterize enzyme active site with aromatic proteins especially tryptophan residues. Conclusion: Research findings shows the dominance of AChE protein in the Head region, hence high enzyme activity (useful for nervous coordination) as well as presence of tryptophan residues at the enzyme active site. The importance of research is useful in enzymology, neuroscience and public health.

A six- or sevenfold coordinated divalent cation in the active site of human PSP makes the difference

2004 ◽  
Vol 60 (a1) ◽  
pp. s163-s163
Author(s):  
C. De Ranter ◽  
Y. Peeraer ◽  
A. Rabijnsa ◽  
J.-F. Collet ◽  
E. Van Schaftingen
Keyword(s):  
Divalent Cation ◽  
Active Site ◽  
The Difference

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals Conformation-Specific Inhibitory Anti-MMP-7 Monoclonal Antibody Sensitizes Pancreatic Ductal Adenocarcinoma Cells to Chemotherapeutic Cell Kill

Cancers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1679
Author(s):  
Vishnu Mohan ◽  
Jean P. Gaffney ◽  
Inna Solomonov ◽  
Maxim Levin ◽  
Mordehay Klepfish ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Active Site ◽  
Drug Targets ◽  
Fas Ligand ◽  
Specific Activity ◽  
Matrix Metalloproteases ◽  
Ductal Adenocarcinoma ◽  
Enzyme Active Site ◽  
Induced Apoptosis

Matrix metalloproteases (MMPs) undergo post-translational modifications including pro-domain shedding. The activated forms of these enzymes are effective drug targets, but generating potent biological inhibitors against them remains challenging. We report the generation of anti-MMP-7 inhibitory monoclonal antibody (GSM-192), using an alternating immunization strategy with an active site mimicry antigen and the activated enzyme. Our protocol yielded highly selective anti-MMP-7 monoclonal antibody, which specifically inhibits MMP-7′s enzyme activity with high affinity (IC50 = 132 ± 10 nM). The atomic model of the MMP-7-GSM-192 Fab complex exhibited antibody binding to unique epitopes at the rim of the enzyme active site, sterically preventing entry of substrates into the catalytic cleft. In human PDAC biopsies, tissue staining with GSM-192 showed characteristic spatial distribution of activated MMP-7. Treatment with GSM-192 in vitro induced apoptosis via stabilization of cell surface Fas ligand and retarded cell migration. Co-treatment with GSM-192 and chemotherapeutics, gemcitabine and oxaliplatin elicited a synergistic effect. Our data illustrate the advantage of precisely targeting catalytic MMP-7 mediated disease specific activity.

scholarly journals The Physical Adsorption of Gelatinized Starch with Tannic Acid Decreases the Inhibitory Activity of the Polyphenol against α-Amylase

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1233
Author(s):  
Yueyi Wang ◽  
Shuangshuang Li ◽  
Fangting Bai ◽  
Junwei Cao ◽  
Lijun Sun
Keyword(s):  
Enzyme Inhibition ◽  
Tannic Acid ◽  
Inhibitory Activity ◽  
Adsorption Property ◽  
Physical Adsorption ◽  
Enzyme Active Site ◽  
Opposite Trend ◽  
Gelatinized Starch ◽  
The Difference

The effects of mixing orders of tannic acid (TA), starch, and α-amylase on the enzyme inhibition of TA were studied, including mixing TA with α-amylase before starch addition (order 1), mixing TA with pre-gelatinized starch before α-amylase addition (order 2) and co-gelatinizing TA with starch before α-amylase addition (order 3). It was found that the enzyme inhibition was always highest for order 1 because TA could bind with the enzyme active site thoroughly before digestion occurred. Both order 2 and 3 reduced α-amylase inhibition through decreasing binding of TA with the enzyme, which resulted from the non-covalent physical adsorption of TA with gelatinized starch. Interestingly, at low TA concentration, α-amylase inhibition for order 2 was higher than order 3, while at high TA concentration, the inhibition was shown with the opposite trend, which arose from the difference in the adsorption property between the pre-gelatinized and co-gelatinized starch at the corresponding TA concentrations. Moreover, both the crystalline structures and apparent morphology of starch were not significantly altered by TA addition for order 2 and 3. Conclusively, although a polyphenol has an acceptable inhibitory activity in vitro, the actual effect may not reach the expected one when taking processing procedures into account.

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